PMCC PMCC

Search tips
Search criteria

Advanced
Results 1-25 (1425272)

Clipboard (0)
None

Related Articles

1.  Therapy of hypoparathyroidism with intact parathyroid hormone 
Summary
Hypoparathyroidism, a disorder characterized by low parathyroid hormone (PTH), is generally treated with oral calcium and vitamin D supplementation. We investigated the effects of PTH(1–84) treatment in 30 hypoparathyroid subjects for 24 months. PTH(1–84) treatment in hypoparathyroidism significantly reduced supplemental calcium and 1,25-dihydroxyvitamin D requirements without generally altering serum and urinary calcium levels.
Introduction
Hypoparathyroidism, a disorder characterized by low PTH, is associated with hypocalcemia, hypercalciuria, and increased bone mineral density (BMD). Conventional therapy with calcium and 1,25-dihydroxyvitamin D can maintain the serum calcium concentration, but doses are high, and control is variable. We investigated the effects of human PTH(1–84) treatment in hypoparathyroidism.
Methods
Thirty subjects with hypoparathyroidism were treated in an open-label study of PTH(1–84) 100 μg every other day by subcutaneous injection for 24 months, with monitoring of calcium and vitamin D supplementation requirements, serum and 24 h urinary calcium excretion, and BMD by dual energy X-ray absorptiometry.
Results
Requirements for supplemental calcium decreased significantly (3,030±2,325 to 1,661±1,267 mg/day (mean± SD); p<0.05), as did requirements for supplemental 1,25-dihydroxyvitamin D (0.68±0.5 to 0.40±0.5 μg/day; p< 0.05). Serum calcium levels and 24 h urinary calcium excretion were mostly unchanged at 24 months. BMD increased at the lumbar spine by 2.9±4% from baseline (p<0.05), while femoral neck BMD remained unchanged and distal one third radial BMD decreased by 2.4±4% (p<0.05).
Conclusion
PTH(1–84) treatment in hypoparathyroidism significantly reduces supplemental calcium and 1,25-dihydroxyvitamin D requirements without generally altering serum and urinary calcium levels.
doi:10.1007/s00198-009-1149-x
PMCID: PMC2947814  PMID: 20094706
Calcium; Hypoparathyroidism; PTH(1–84)
2.  Prevalence of Hypoparathyroidism (HPT) in Beta Thalassemia Major 
Introduction: The aim of this study was to assess the parathyroid functions and bone mineral density (BMD) in patients with beta thalassemia and to correlate them with serum ferritin, calcium, phosphorus and alkaline phosphatase levels.
Materials and Methods: This is a case control study which was done on 55 subjects (40 cases and 15 controls) in the age group of 2-18 years. The cases included were with confirmed diagnosis of beta thalassemia major, more than ten blood transfusions and serum ferritin levels >2000 μg/L irrespective of chelation therapy.
Results: Significant Hypoparathyroidism (HPT) observed along with low BMD levels in beta thalassemia patients (p < 0.01).
A significant decrease in serum calcium level was seen in cases when compared to controls, where as the levels of both serum phosphorus and alkaline phosphatase levels increased in cases when compared to controls.
Conclusion: BMD and PTH levels are very useful tools for diagnosing HPT. As a routine, in beta thalassemia major, screening for vitamin D deficiency and hypocalcemia should be done in second decade of life and as a preventive measure they should be supplemented with calcium and vitamin D to prevent hypocalcemic tetany, to facilitate bone growth and to prevent fractures.
doi:10.7860/JCDR/2014/6672.3997
PMCID: PMC3972574  PMID: 24701472
Bone mineral density (BMD); Parathyroid hormone (PTH); Dual energy X-ray absorptiometry (DEXA)
3.  Effects of paricalcitol on calcium and phosphate metabolism and markers of bone health in patients with diabetic nephropathy: results of the VITAL study 
Nephrology Dialysis Transplantation  2013;28(9):2260-2268.
Background
Chronic kidney disease (CKD) is associated with elevations in serum phosphate, calcium–phosphorus product and bone-specific alkaline phosphatase (BAP), with attendant risks of cardiovascular and bone disorders. Active vitamin D can suppress parathyroid hormone (PTH), but may raise serum calcium and phosphate concentrations. Paricalcitol, a selective vitamin D activator, suppressed PTH in CKD patients (stages 3 and 4) with secondary hyperparathyroidism (SHPT) with minimal changes in calcium and phosphate metabolism.
Methods
The VITAL study enrolled patients with CKD stages 2–4. We examined the effect and relationship of paricalcitol to calcium and phosphate metabolism and bone markers in a post hoc analysis of VITAL. The study comprised patients with diabetic nephropathy enrolled in a double-blind, placebo-controlled, randomized trial of paricalcitol (1 or 2 μg/day). Urinary and serum calcium and phosphate, serum BAP, and intact PTH (iPTH) concentrations were measured throughout the study.
Results
Baseline demographics and calcium, phosphate, PTH (49% with iPTH <70 pg/mL), and BAP concentrations were similar between groups. A transient, modest yet significant increase in phosphate was observed for paricalcitol 2 μg/day (+0.29 mg/dL; P < 0.001). Dose-dependent increases in serum and urinary calcium were observed; however, there were few cases of hypercalcemia: one in the 1-μg/day group (1.1%) and three in the 2-μg/day group (3.2%). Significant reductions in BAP were observed that persisted for 60 days after paricalcitol discontinuation (P < 0.001 for combined paricalcitol groups versus placebo). Paricalcitol dose-dependent reductions in iPTH were observed. Paricalcitol in CKD patients (±SHPT) was associated with modest increases in calcium and phosphate.
Conclusion
Paricalcitol reduces BAP levels, which may be beneficial for reducing vascular calcification.
Trial registration
Trial is registered with ClinicalTrials.gov, number NCT00421733.
doi:10.1093/ndt/gft227
PMCID: PMC3769981  PMID: 23787544
bone-specific alkaline phosphatase; calcitriol; hypercalcemia; hyperphosphatemia; paricalcitol; vitamin D receptor activation
4.  Inappropriate phosphate excretion in idiopathic hypercalciuria: the key to a common cause and future treatment? 
Journal of Clinical Pathology  1996;49(11):881-888.
AIMS: To present experimental evidence in support of a proposed common cause for absorptive hypercalciuria, renal hypercalciuria, renal phosphate leak and enhancement of 1,25-(OH)2-vitamin D concentrations in patients presenting with renal stone disease; and to suggest further investigation with a view to new management. METHODS: An oral calcium loading test was administered to 15 patients with renal stones and 10 normal controls in the fasting state: urine and blood were collected hourly. After the second urine sample, 400 mg calcium dissolved in water was administered orally. Serum calcium, albumin, parathyroid hormone (PTH), and phosphate were measured together with urine calcium clearance and urinary phosphate from which the TmPO4/glomerular filtration rate (GFR) ratio was calculated. Serum 1,25-(OH)2-vitamin D was measured in the first serum sample. In addition, 24 hour urine calcium results were collected retrospectively from the patients' case notes over the previous 18 months. RESULTS: In the basal state, renal stone patients had an overall greater phosphaturia (lower TmPO4/GFR: median 1.72 compared with 2.10 in controls) and increased calcium clearance. Serum corrected calcium and PTH concentrations did not differ between the groups. After calcium loading, serum calcium and urine calcium clearance rose in both groups, with patients with renal stones experiencing a greater percentage fall in phosphaturia. In both groups TmPO4/GFR fell (greater phosphaturia) with increased serum corrected calcium, with the patients showing notably greater phosphaturia for any given calcium concentration. Patients also had notably greater phosphaturia compared with the serum calcium concentration for any given PTH value. Serum 1,25-(OH)2-vitamin D was higher in patients than controls and for any 1,25-(OH)2-vitamin D concentration phosphaturia measured against serum calcium was greater in patients than controls. 1,25-(OH)2-vitamin D did not correlate with phosphaturia relative to serum calcium concentrations within the patient and control groups. CONCLUSIONS: It is proposed that patients with idiopathic hypercalciuria have an "inappropriately' high phosphate excretion for any given serum calcium concentration. Loss of phosphate may induce increased activation of 1,25-(OH)2-vitamin D. Some of the commonly described causes of stone formation may be manifestations of a single mechanism.
PMCID: PMC500825  PMID: 8944605
5.  A randomized, double-blind, placebo-controlled trial of calcium acetate on serum phosphorus concentrations in patients with advanced non-dialysis-dependent chronic kidney disease 
BMC Nephrology  2011;12:9.
Background
Hyperphosphatemia in patients with chronic kidney disease (CKD) contributes to secondary hyperparathyroidism, soft tissue calcification, and increased mortality risk. This trial was conducted to examine the efficacy and safety of calcium acetate in controlling serum phosphorus in pre-dialysis patients with CKD.
Methods
In this randomized, double-blind, placebo-controlled trial, 110 nondialyzed patients from 34 sites with estimated GFR < 30 mL/min/1.73 m2 and serum phosphorus > 4.5 mg/dL were randomized to calcium acetate or placebo for 12 weeks. The dose of study drugs was titrated to achieve target serum phosphorus of 2.7-4.5 mg/dL. Serum phosphorus, calcium, iPTH, bicarbonate and serum albumin were measured at baseline and every 2 weeks for the 12 week study period. The primary efficacy endpoint was serum phosphorus at 12 weeks. Secondary endpoints were to measure serum calcium and intact parathyroid hormone (iPTH) levels.
Results
At 12 weeks, serum phosphorus concentration was significantly lower in the calcium acetate group compared to the placebo group (4.4 ± 1.2 mg/dL vs. 5.1 ± 1.4 mg/dL; p = 0.04). The albumin-adjusted serum calcium concentration was significantly higher (9.5 ± 0.8 vs. 8.8 ± 0.8; p < 0.001) and iPTH was significantly lower in the calcium acetate group compared to placebo (150 ± 157 vs. 351 ± 292 pg/mL respectively; p < 0.001). At 12 weeks, the proportions of subjects who had hypocalcemia were 5.4% and 19.5% for the calcium acetate and the placebo groups, respectively, while the proportions of those with hypercalcemia were 13.5% and 0%, respectively. Adverse events did not differ between the treatment groups.
Conclusions
In CKD patients not yet on dialysis, calcium acetate was effective in reducing serum phosphorus and iPTH over a 12 week period.
Trial Registration
www.clinicaltrials.gov NCT00211978.
doi:10.1186/1471-2369-12-9
PMCID: PMC3055808  PMID: 21324193
6.  The Abnormal Phenotypes of Cartilage and Bone in Calcium-Sensing Receptor Deficient Mice Are Dependent on the Actions of Calcium, Phosphorus, and PTH 
PLoS Genetics  2011;7(9):e1002294.
Patients with neonatal severe hyperparathyroidism (NSHPT) are homozygous for the calcium-sensing receptor (CaR) mutation and have very high circulating PTH, abundant parathyroid hyperplasia, and severe life-threatening hypercalcemia. Mice with homozygous deletion of CaR mimic the syndrome of NSHPT. To determine effects of CaR deficiency on skeletal development and interactions between CaR and 1,25(OH)2D3 or PTH on calcium and skeletal homeostasis, we compared the skeletal phenotypes of homozygous CaR–deficient (CaR−/−) mice to those of double homozygous CaR– and 1α(OH)ase–deficient [CaR−/−1α(OH)ase−/−] mice or those of double homozygous CaR– and PTH–deficient [CaR−/−PTH−/−] mice at 2 weeks of age. Compared to wild-type littermates, CaR−/− mice had hypercalcemia, hypophosphatemia, hyperparathyroidism, and severe skeletal growth retardation. Chondrocyte proliferation and PTHrP expression in growth plates were reduced significantly, whereas trabecular volume, osteoblast number, osteocalcin-positive areas, expression of the ALP, type I collagen, osteocalcin genes, and serum ALP levels were increased significantly. Deletion of 1α(OH)ase in CaR−/− mice resulted in a longer lifespan, normocalcemia, lower serum phosphorus, greater elevation in PTH, slight improvement in skeletal growth with increased chondrocyte proliferation and PTHrP expression, and further increases in indices of osteoblastic bone formation. Deletion of PTH in CaR−/− mice resulted in rescue of early lethality, normocalcemia, increased serum phosphorus, undetectable serum PTH, normalization in skeletal growth with normal chondrocyte proliferation and enhanced PTHrP expression, and dramatic decreases in indices of osteoblastic bone formation. Our results indicate that reductions in hypercalcemia play a critical role in preventing the early lethality of CaR−/− mice and that defects in endochondral bone formation in CaR−/− mice result from effects of the marked elevation in serum calcium concentration and the decreases in serum phosphorus concentration and skeletal PTHrP levels, whereas the increased osteoblastic bone formation results from direct effects of PTH.
Author Summary
Mice with homozygous deletion of the calcium-sensing receptor (CaR) mimic the syndrome of neonatal severe hyperparathyroidism (NSHPT) in humans with very high circulating parathyroid hormone (PTH) and severe life-threatening hypercalcemia. To determine effects of CaR deficiency on skeletal development and interactions between CaR and 1,25(OH)2D3 or PTH on calcium and skeletal homeostasis, we compared the skeletal phenotypes of homozygous CaR–deficient mice to those of double homozygous CaR– and 1,25(OH)2D3–deficient mice or those of double homozygous CaR– and PTH–deficient mice. CaR–deficient mice had hypercalcemia, hypophosphatemia, hyperparathyroidism, severe skeletal growth retardation, and abnormalities; and most died within 2 weeks of age. Deletion of 1,25(OH)2D3 in CaR–deficient mice resulted in a longer lifespan, normocalcemia, lower serum phosphorus, greater elevation in PTH, and slight improvement in skeletal growth. Deletion of PTH in CaR–deficient mice resulted in rescue of early lethality, normocalcemia, increased serum phosphorus, and normalization in skeletal growth. Our results indicate that reductions in hypercalcemia reduce the early lethality of CaR–deficient mice and that deletion of PTH in patients with NSHPT may normalize skeletal growth and development.
doi:10.1371/journal.pgen.1002294
PMCID: PMC3178615  PMID: 21966280
7.  Human Parathyroid Hormone Is Secreted Primarily into the Bloodstream After Rat Parotid Gland Gene Transfer 
Human Gene Therapy  2010;22(1):84-92.
Abstract
Hypoparathyroidism is a hormone deficiency syndrome that leads to low blood calcium levels and for which current replacement therapy is inadequate. Gene transfer to salivary glands leads to safe and abundant secretion of therapeutic protein into either saliva or the bloodstream. We previously reported the successful transduction of rat submandibular glands with an adenoviral vector encoding human parathyroid hormone (Ad.hPTH), but unfortunately most of the hPTH was secreted into saliva. Because submandibular and parotid glands are morphologically and functionally different, we hypothesized that hPTH sorting might be different in parotid glands. After 2 days, the pattern of hPTH secretion from transduced parotid glands of intact rats was reversed from that of transduced submandibular glands, that is, most transgenic hPTH was detected in serum (5 × 1010 viral particles per gland; the saliva-to-serum ratio of total hPTH secreted was 0.04). Vector copies were localized to the targeted parotid glands, with none detected in liver or spleen. Ad.hPTH next was administered to parotid glands of parathyroidectomized rats. Two days after delivery no hPTH was detectable in saliva, but high levels were found in serum, leading to normalization of serum calcium and a significant increase in the urinary phosphorus-to-creatinine ratio. This study demonstrates for the first time differential sorting of transgenic hPTH between submandibular and parotid glands, suggesting that hPTH may be a valuable model protein for understanding the molecular basis of transgenic secretory protein sorting in these exocrine glands. We also show the clinical potential of salivary gland hPTH gene therapy for patients with hypoparathyroidism.
Physiologically sufficient levels of calcium in the blood are important for a range of vital functions and hypocalcemia can lead to seizures, tetany, or heart failure. Parathyroid hormone (PTH) is central to maintaining adequate blood calcium concentration. In this study, Adriaansen et al. demonstrate that delivery of an adenoviral vector encoding human PTH to the parotid gland of hypocalcemic rats leads to a normalization of serum calcium levels.
doi:10.1089/hum.2010.097
PMCID: PMC3025188  PMID: 20977345
8.  Changes in Serum and Urinary Calcium during Treatment with Hydrochlorothiazide: Studies on Mechanisms 
Journal of Clinical Investigation  1972;51(4):945-954.
Studies were undertaken in man to evaluate the roles of volume depletion and of the parathyroid glands in mediating the changes in serum and urinary calcium which follow the administration of hydrochlorothiazide, 100 mg twice daily, for 4 days, 42 studies were carried out in 16 normal subjects, 9 patients with hyperparathyroidism, and 7 vitamin D-treated subjects with hypoparathyroidism. In six studies in normal subjects, daily sodium losses during thiazide administration were quantitatively replaced, and in six other studies the effect of equivalent sodium losses produced by furosemide was evaluated.
Although the magnitude of sodium losses was similar in three groups during therapy with thiazides, urinary calcium fell and urinary phosphorus increased significantly only in normal subjects and those with hyperparathyroidism; no change occurred in patients with hypoparathyroidism. With the replacement of the thiazide-induced sodium losses by NaCl in normals, urinary calcium did not change as urinary sodium increased 4- to 5-fold. Furosemide administration produced similar sodium losses while urinary calcium remained at or above control levels. After correction for changes in plasma protein concentration caused by thiazide-induced hemoconcentration, mean levels of serum calcium were significantly increased only in subjects with hyperparathyroidism and vitamin D-treated patients with hypoparathyroidism.
The results indicate that both depletion of extracellular fluid volume and the presence of the parathyroid glands are necessary for the decrease in urinary calcium in response to thiazide therapy. Both the reduction in urinary calcium and increase in urinary phosphate after the use of thiazides may be due, in part, to potentiation of the action of the parathyroid hormone on the nephron. The rise in serum calcium could be due to thiazide-induced release of calcium from bone into extracellular fluid, particularly in states where bone resorption may be augmented, i.e., vitamin D therapy or hyperparathyroidism.
PMCID: PMC302208  PMID: 4552338
9.  The high prevalence of chronic kidney disease-mineral bone disorders: A hospital-based cross-sectional study 
Indian Journal of Nephrology  2012;22(4):285-291.
Mineral bone disorder (MBD) is an important complication of chronic kidney disease (CKD). However, there are limited data on the pattern of MBD in Indian CKD population. The aim of this study was to describe spectrum of MBD in patients with CKD in our center. This was a hospital-based cross-sectional observational study. Patients with stage 4 and 5 CKD were included in this study. Those receiving calcium supplement, vitamin D or its analogues, and calcimimetic were excluded. Serum/plasma levels of creatinine, albumin, calcium, phosphate, total alkaline phosphatase (TAP), intact parathormone (iPTH), and 25-OH vitaminD (25-vitD) were measured. Radiological survey of bones was carried out in all cases, and echocardiography done in selected patients. Statistical analysis was done using Sigmaplot 10.0 software. A total of 150 patients (114 males, 36 females) were included in this study. Mean age was 45.67±16.96 years. CKD stage 4 and 5D were found in 26% (n=39) and 74% (n=111) of study population, respectively. The most common underlying native kidney diseases in patients of CKD 4 and 5D were diabetic nephropathy (41.03%) and CGN (41.44%), respectively. Median (first quartile, third quartile) values for serum levels of corrected calcium (cCa), phosphate, cCaXPO4 product, TAP, plasma iPTH, and 25-vitD in stage 4 CKD were 8.36 (7.79, 8.91) mg/dL, 4.9 (3.92, 6.4) mg/dL, 41.11 (34.01, 53.81) mg2/dL2, 97 (76.5, 184.25) IU/L, 231 (124.5, 430.75) pg/mL, and 12 (6.98, 23.55) ng/mL, respectively; and in stage 5D CKD were 8.36 (7.66, 8.95) mg/dL, 5.7 (4.23, 6.95) mg/dL, 46.5 (37.16, 54.47) mg2/dL2, 180 (114.5, 276.25) IU/L, 288 (169.75, 625.0) pg/mL, and 18.4 (10.0, 26.4) ng/mL, respectively. Prevalence of hypocalcemia (56.41% vs. 54.95%), hyperphosphatemia (64.10% vs. 70.27%), and hyperparathyroidism (84.62% vs. 88.29%) was not different between patients with CKD 4 and 5D. However, iPTH level outside the target range and increased TAP level were significantly (P<0.001) more common in CKD stage 5D. Multiple logistic regression analysis for hyperparathyroidism revealed significant inverse correlation with cCa in CKD 5D. There were no significant differences in vitamin D status and prevalence of valvular calcification between CKD stage 4 and 5D. X-ray revealed renal osteodystrophy in 8 (5.33%) patients, while it was normal in 118 (78.67%) patients. Secondary hyperparathyroidism, hyperphosphatemia, hypocalcemia, increased TAP, and 25-OH vitamin D deficiency and insufficiency were quite common in CKD 4 and 5 patients. The commonest type of MBD in CKD 4 and 5D was secondary hyperparathyroidism.
doi:10.4103/0971-4065.101249
PMCID: PMC3495351  PMID: 23162273
Chronic kidney disease; hyperparathyroidism; hyperphosphatemia; hypocalcemia; mineral bone disorder
10.  Clinical Utility of Vitamin D Testing 
Executive Summary
This report from the Medical Advisory Secretariat (MAS) was intended to evaluate the clinical utility of vitamin D testing in average risk Canadians and in those with kidney disease. As a separate analysis, this report also includes a systematic literature review of the prevalence of vitamin D deficiency in these two subgroups.
This evaluation did not set out to determine the serum vitamin D thresholds that might apply to non-bone health outcomes. For bone health outcomes, no high or moderate quality evidence could be found to support a target serum level above 50 nmol/L. Similarly, no high or moderate quality evidence could be found to support vitamin D’s effects in non-bone health outcomes, other than falls.
Vitamin D
Vitamin D is a lipid soluble vitamin that acts as a hormone. It stimulates intestinal calcium absorption and is important in maintaining adequate phosphate levels for bone mineralization, bone growth, and remodelling. It’s also believed to be involved in the regulation of cell growth proliferation and apoptosis (programmed cell death), as well as modulation of the immune system and other functions. Alone or in combination with calcium, Vitamin D has also been shown to reduce the risk of fractures in elderly men (≥ 65 years), postmenopausal women, and the risk of falls in community-dwelling seniors. However, in a comprehensive systematic review, inconsistent results were found concerning the effects of vitamin D in conditions such as cancer, all-cause mortality, and cardiovascular disease. In fact, no high or moderate quality evidence could be found concerning the effects of vitamin D in such non-bone health outcomes. Given the uncertainties surrounding the effects of vitamin D in non-bone health related outcomes, it was decided that this evaluation should focus on falls and the effects of vitamin D in bone health and exclusively within average-risk individuals and patients with kidney disease.
Synthesis of vitamin D occurs naturally in the skin through exposure to ultraviolet B (UVB) radiation from sunlight, but it can also be obtained from dietary sources including fortified foods, and supplements. Foods rich in vitamin D include fatty fish, egg yolks, fish liver oil, and some types of mushrooms. Since it is usually difficult to obtain sufficient vitamin D from non-fortified foods, either due to low content or infrequent use, most vitamin D is obtained from fortified foods, exposure to sunlight, and supplements.
Clinical Need: Condition and Target Population
Vitamin D deficiency may lead to rickets in infants and osteomalacia in adults. Factors believed to be associated with vitamin D deficiency include:
darker skin pigmentation,
winter season,
living at higher latitudes,
skin coverage,
kidney disease,
malabsorption syndromes such as Crohn’s disease, cystic fibrosis, and
genetic factors.
Patients with chronic kidney disease (CKD) are at a higher risk of vitamin D deficiency due to either renal losses or decreased synthesis of 1,25-dihydroxyvitamin D.
Health Canada currently recommends that, until the daily recommended intakes (DRI) for vitamin D are updated, Canada’s Food Guide (Eating Well with Canada’s Food Guide) should be followed with respect to vitamin D intake. Issued in 2007, the Guide recommends that Canadians consume two cups (500 ml) of fortified milk or fortified soy beverages daily in order to obtain a daily intake of 200 IU. In addition, men and women over the age of 50 should take 400 IU of vitamin D supplements daily. Additional recommendations were made for breastfed infants.
A Canadian survey evaluated the median vitamin D intake derived from diet alone (excluding supplements) among 35,000 Canadians, 10,900 of which were from Ontario. Among Ontarian males ages 9 and up, the median daily dietary vitamin D intake ranged between 196 IU and 272 IU per day. Among females, it varied from 152 IU to 196 IU per day. In boys and girls ages 1 to 3, the median daily dietary vitamin D intake was 248 IU, while among those 4 to 8 years it was 224 IU.
Vitamin D Testing
Two laboratory tests for vitamin D are available, 25-hydroxy vitamin D, referred to as 25(OH)D, and 1,25-dihydroxyvitamin D. Vitamin D status is assessed by measuring the serum 25(OH)D levels, which can be assayed using radioimmunoassays, competitive protein-binding assays (CPBA), high pressure liquid chromatography (HPLC), and liquid chromatography-tandem mass spectrometry (LC-MS/MS). These may yield different results with inter-assay variation reaching up to 25% (at lower serum levels) and intra-assay variation reaching 10%.
The optimal serum concentration of vitamin D has not been established and it may change across different stages of life. Similarly, there is currently no consensus on target serum vitamin D levels. There does, however, appear to be a consensus on the definition of vitamin D deficiency at 25(OH)D < 25 nmol/l, which is based on the risk of diseases such as rickets and osteomalacia. Higher target serum levels have also been proposed based on subclinical endpoints such as parathyroid hormone (PTH). Therefore, in this report, two conservative target serum levels have been adopted, 25 nmol/L (based on the risk of rickets and osteomalacia), and 40 to 50 nmol/L (based on vitamin D’s interaction with PTH).
Ontario Context
Volume & Cost
The volume of vitamin D tests done in Ontario has been increasing over the past 5 years with a steep increase of 169,000 tests in 2007 to more than 393,400 tests in 2008. The number of tests continues to rise with the projected number of tests for 2009 exceeding 731,000. According to the Ontario Schedule of Benefits, the billing cost of each test is $51.7 for 25(OH)D (L606, 100 LMS units, $0.517/unit) and $77.6 for 1,25-dihydroxyvitamin D (L605, 150 LMS units, $0.517/unit). Province wide, the total annual cost of vitamin D testing has increased from approximately $1.7M in 2004 to over $21.0M in 2008. The projected annual cost for 2009 is approximately $38.8M.
Evidence-Based Analysis
The objective of this report is to evaluate the clinical utility of vitamin D testing in the average risk population and in those with kidney disease. As a separate analysis, the report also sought to evaluate the prevalence of vitamin D deficiency in Canada. The specific research questions addressed were thus:
What is the clinical utility of vitamin D testing in the average risk population and in subjects with kidney disease?
What is the prevalence of vitamin D deficiency in the average risk population in Canada?
What is the prevalence of vitamin D deficiency in patients with kidney disease in Canada?
Clinical utility was defined as the ability to improve bone health outcomes with the focus on the average risk population (excluding those with osteoporosis) and patients with kidney disease.
Literature Search
A literature search was performed on July 17th, 2009 using OVID MEDLINE, MEDLINE In-Process and Other Non-Indexed Citations, EMBASE, the Cumulative Index to Nursing & Allied Health Literature (CINAHL), the Cochrane Library, and the International Agency for Health Technology Assessment (INAHTA) for studies published from January 1, 1998 until July 17th, 2009. Abstracts were reviewed by a single reviewer and, for those studies meeting the eligibility criteria, full-text articles were obtained. Reference lists were also examined for any additional relevant studies not identified through the search. Articles with unknown eligibility were reviewed with a second clinical epidemiologist, then a group of epidemiologists until consensus was established. The quality of evidence was assessed as high, moderate, low or very low according to GRADE methodology.
Observational studies that evaluated the prevalence of vitamin D deficiency in Canada in the population of interest were included based on the inclusion and exclusion criteria listed below. The baseline values were used in this report in the case of interventional studies that evaluated the effect of vitamin D intake on serum levels. Studies published in grey literature were included if no studies published in the peer-reviewed literature were identified for specific outcomes or subgroups.
Considering that vitamin D status may be affected by factors such as latitude, sun exposure, food fortification, among others, the search focused on prevalence studies published in Canada. In cases where no Canadian prevalence studies were identified, the decision was made to include studies from the United States, given the similar policies in vitamin D food fortification and recommended daily intake.
Inclusion Criteria
Studies published in English
Publications that reported the prevalence of vitamin D deficiency in Canada
Studies that included subjects from the general population or with kidney disease
Studies in children or adults
Studies published between January 1998 and July 17th 2009
Exclusion Criteria
Studies that included subjects defined according to a specific disease other than kidney disease
Letters, comments, and editorials
Studies that measured the serum vitamin D levels but did not report the percentage of subjects with serum levels below a given threshold
Outcomes of Interest
Prevalence of serum vitamin D less than 25 nmol/L
Prevalence of serum vitamin D less than 40 to 50 nmol/L
Serum 25-hydroxyvitamin D was the metabolite used to assess vitamin D status. Results from adult and children studies were reported separately. Subgroup analyses according to factors that affect serum vitamin D levels (e.g., seasonal effects, skin pigmentation, and vitamin D intake) were reported if enough information was provided in the studies
Quality of Evidence
The quality of the prevalence studies was based on the method of subject recruitment and sampling, possibility of selection bias, and generalizability to the source population. The overall quality of the trials was examined according to the GRADE Working Group criteria.
Summary of Findings
Fourteen prevalence studies examining Canadian adults and children met the eligibility criteria. With the exception of one longitudinal study, the studies had a cross-sectional design. Two studies were conducted among Canadian adults with renal disease but none studied Canadian children with renal disease (though three such US studies were included). No systematic reviews or health technology assessments that evaluated the prevalence of vitamin D deficiency in Canada were identified. Two studies were published in grey literature, consisting of a Canadian survey designed to measure serum vitamin D levels and a study in infants presented as an abstract at a conference. Also included were the results of vitamin D tests performed in community laboratories in Ontario between October 2008 and September 2009 (provided by the Ontario Association of Medical Laboratories).
Different threshold levels were used in the studies, thus we reported the percentage of subjects with serum levels of between 25 and 30 nmol/L and between 37.5 and 50 nmol/L. Some studies stratified the results according to factors affecting vitamin D status and two used multivariate models to investigate the effects of these characteristics (including age, season, BMI, vitamin D intake, skin pigmentation, and season) on serum 25(OH)D levels. It’s unclear, however, if these studies were adequately powered for these subgroup analyses.
Study participants generally consisted of healthy, community-dwelling subjects and most excluded individuals with conditions or medications that alter vitamin D or bone metabolism, such as kidney or liver disease. Although the studies were conducted in different parts of Canada, fewer were performed in Northern latitudes, i.e. above 53°N, which is equivalent to the city of Edmonton.
Adults
Serum vitamin D levels of < 25 to 30 nmol/L were observed in 0% to 25.5% of the subjects included in five studies; the weighted average was 3.8% (95% CI: 3.0, 4.6). The preliminary results of the Canadian survey showed that approximately 5% of the subjects had serum levels below 29.5 nmol/L. The results of over 600,000 vitamin D tests performed in Ontarian community laboratories between October 2008 and September 2009 showed that 2.6% of adults (> 18 years) had serum levels < 25 nmol/L.
The prevalence of serum vitamin D levels below 37.5-50 nmol/L reported among studies varied widely, ranging from 8% to 73.6% with a weighted average of 22.5%. The preliminary results of the CHMS survey showed that between 10% and 25% of subjects had serum levels below 37 to 48 nmol/L. The results of the vitamin D tests performed in community laboratories showed that 10% to 25% of the individuals had serum levels between 39 and 50 nmol/L.
In an attempt to explain this inter-study variation, the study results were stratified according to factors affecting serum vitamin D levels, as summarized below. These results should be interpreted with caution as none were adjusted for other potential confounders. Adequately powered multivariate analyses would be necessary to determine the contribution of risk factors to lower serum 25(OH)D levels.
Seasonal variation
Three adult studies evaluating serum vitamin D levels in different seasons observed a trend towards a higher prevalence of serum levels < 37.5 to 50 nmol/L during the winter and spring months, specifically 21% to 39%, compared to 8% to 14% in the summer. The weighted average was 23.6% over the winter/spring months and 9.6% over summer. The difference between the seasons was not statistically significant in one study and not reported in the other two studies.
Skin Pigmentation
Four studies observed a trend toward a higher prevalence of serum vitamin D levels < 37.5 to 50 nmol/L in subjects with darker skin pigmentation compared to those with lighter skin pigmentation, with weighted averages of 46.8% among adults with darker skin colour and 15.9% among those with fairer skin.
Vitamin D intake and serum levels
Four adult studies evaluated serum vitamin D levels according to vitamin D intake and showed an overall trend toward a lower prevalence of serum levels < 37.5 to 50 nmol/L with higher levels of vitamin D intake. One study observed a dose-response relationship between higher vitamin D intake from supplements, diet (milk), and sun exposure (results not adjusted for other variables). It was observed that subjects taking 50 to 400 IU or > 400 IU of vitamin D per day had a 6% and 3% prevalence of serum vitamin D level < 40 nmol/L, respectively, versus 29% in subjects not on vitamin D supplementation. Similarly, among subjects drinking one or two glasses of milk per day, the prevalence of serum vitamin D levels < 40 nmol/L was found to be 15%, versus 6% in those who drink more than two glasses of milk per day and 21% among those who do not drink milk. On the other hand, one study observed little variation in serum vitamin D levels during winter according to milk intake, with the proportion of subjects exhibiting vitamin D levels of < 40 nmol/L being 21% among those drinking 0-2 glasses per day, 26% among those drinking > 2 glasses, and 20% among non-milk drinkers.
The overall quality of evidence for the studies conducted among adults was deemed to be low, although it was considered moderate for the subgroups of skin pigmentation and seasonal variation.
Newborn, Children and Adolescents
Five Canadian studies evaluated serum vitamin D levels in newborns, children, and adolescents. In four of these, it was found that between 0 and 36% of children exhibited deficiency across age groups with a weighted average of 6.4%. The results of over 28,000 vitamin D tests performed in children 0 to 18 years old in Ontario laboratories (Oct. 2008 to Sept. 2009) showed that 4.4% had serum levels of < 25 nmol/L.
According to two studies, 32% of infants 24 to 30 months old and 35.3% of newborns had serum vitamin D levels of < 50 nmol/L. Two studies of children 2 to 16 years old reported that 24.5% and 34% had serum vitamin D levels below 37.5 to 40 nmol/L. In both studies, older children exhibited a higher prevalence than younger children, with weighted averages 34.4% and 10.3%, respectively. The overall weighted average of the prevalence of serum vitamin D levels < 37.5 to 50 nmol/L among pediatric studies was 25.8%. The preliminary results of the Canadian survey showed that between 10% and 25% of subjects between 6 and 11 years (N= 435) had serum levels below 50 nmol/L, while for those 12 to 19 years, 25% to 50% exhibited serum vitamin D levels below 50 nmol/L.
The effects of season, skin pigmentation, and vitamin D intake were not explored in Canadian pediatric studies. A Canadian surveillance study did, however, report 104 confirmed cases1 (2.9 cases per 100,000 children) of vitamin D-deficient rickets among Canadian children age 1 to 18 between 2002 and 2004, 57 (55%) of which from Ontario. The highest incidence occurred among children living in the North, i.e., the Yukon, Northwest Territories, and Nunavut. In 92 (89%) cases, skin pigmentation was categorized as intermediate to dark, 98 (94%) had been breastfed, and 25 (24%) were offspring of immigrants to Canada. There were no cases of rickets in children receiving ≥ 400 IU VD supplementation/day.
Overall, the quality of evidence of the studies of children was considered very low.
Kidney Disease
Adults
Two studies evaluated serum vitamin D levels in Canadian adults with kidney disease. The first included 128 patients with chronic kidney disease stages 3 to 5, 38% of which had serum vitamin D levels of < 37.5 nmol/L (measured between April and July). This is higher than what was reported in Canadian studies of the general population during the summer months (i.e. between 8% and 14%). In the second, which examined 419 subjects who had received a renal transplantation (mean time since transplantation: 7.2 ± 6.4 years), the prevalence of serum vitamin D levels < 40 nmol/L was 27.3%. The authors concluded that the prevalence observed in the study population was similar to what is expected in the general population.
Children
No studies evaluating serum vitamin D levels in Canadian pediatric patients with kidney disease could be identified, although three such US studies among children with chronic kidney disease stages 1 to 5 were. The mean age varied between 10.7 and 12.5 years in two studies but was not reported in the third. Across all three studies, the prevalence of serum vitamin D levels below the range of 37.5 to 50 nmol/L varied between 21% and 39%, which is not considerably different from what was observed in studies of healthy Canadian children (24% to 35%).
Overall, the quality of evidence in adults and children with kidney disease was considered very low.
Clinical Utility of Vitamin D Testing
A high quality comprehensive systematic review published in August 2007 evaluated the association between serum vitamin D levels and different bone health outcomes in different age groups. A total of 72 studies were included. The authors observed that there was a trend towards improvement in some bone health outcomes with higher serum vitamin D levels. Nevertheless, precise thresholds for improved bone health outcomes could not be defined across age groups. Further, no new studies on the association were identified during an updated systematic review on vitamin D published in July 2009.
With regards to non-bone health outcomes, there is no high or even moderate quality evidence that supports the effectiveness of vitamin D in outcomes such as cancer, cardiovascular outcomes, and all-cause mortality. Even if there is any residual uncertainty, there is no evidence that testing vitamin D levels encourages adherence to Health Canada’s guidelines for vitamin D intake. A normal serum vitamin D threshold required to prevent non-bone health related conditions cannot be resolved until a causal effect or correlation has been demonstrated between vitamin D levels and these conditions. This is as an ongoing research issue around which there is currently too much uncertainty to base any conclusions that would support routine vitamin D testing.
For patients with chronic kidney disease (CKD), there is again no high or moderate quality evidence supporting improved outcomes through the use of calcitriol or vitamin D analogs. In the absence of such data, the authors of the guidelines for CKD patients consider it best practice to maintain serum calcium and phosphate at normal levels, while supplementation with active vitamin D should be considered if serum PTH levels are elevated. As previously stated, the authors of guidelines for CKD patients believe that there is not enough evidence to support routine vitamin D [25(OH)D] testing. According to what is stated in the guidelines, decisions regarding the commencement or discontinuation of treatment with calcitriol or vitamin D analogs should be based on serum PTH, calcium, and phosphate levels.
Limitations associated with the evidence of vitamin D testing include ambiguities in the definition of an ‘adequate threshold level’ and both inter- and intra- assay variability. The MAS considers both the lack of a consensus on the target serum vitamin D levels and assay limitations directly affect and undermine the clinical utility of testing. The evidence supporting the clinical utility of vitamin D testing is thus considered to be of very low quality.
Daily vitamin D intake, either through diet or supplementation, should follow Health Canada’s recommendations for healthy individuals of different age groups. For those with medical conditions such as renal disease, liver disease, and malabsorption syndromes, and for those taking medications that may affect vitamin D absorption/metabolism, physician guidance should be followed with respect to both vitamin D testing and supplementation.
Conclusions
Studies indicate that vitamin D, alone or in combination with calcium, may decrease the risk of fractures and falls among older adults.
There is no high or moderate quality evidence to support the effectiveness of vitamin D in other outcomes such as cancer, cardiovascular outcomes, and all-cause mortality.
Studies suggest that the prevalence of vitamin D deficiency in Canadian adults and children is relatively low (approximately 5%), and between 10% and 25% have serum levels below 40 to 50 nmol/L (based on very low to low grade evidence).
Given the limitations associated with serum vitamin D measurement, ambiguities in the definition of a ‘target serum level’, and the availability of clear guidelines on vitamin D supplementation from Health Canada, vitamin D testing is not warranted for the average risk population.
Health Canada has issued recommendations regarding the adequate daily intake of vitamin D, but current studies suggest that the mean dietary intake is below these recommendations. Accordingly, Health Canada’s guidelines and recommendations should be promoted.
Based on a moderate level of evidence, individuals with darker skin pigmentation appear to have a higher risk of low serum vitamin D levels than those with lighter skin pigmentation and therefore may need to be specially targeted with respect to optimum vitamin D intake. The cause-effect of this association is currently unclear.
Individuals with medical conditions such as renal and liver disease, osteoporosis, and malabsorption syndromes, as well as those taking medications that may affect vitamin D absorption/metabolism, should follow their physician’s guidance concerning both vitamin D testing and supplementation.
PMCID: PMC3377517  PMID: 23074397
11.  A randomized controlled trial of cholecalciferol supplementation in patients on maintenance hemodialysis 
Background:
Vitamin D deficiency is common in Indian patients with chronic kidney disease (CKD) on maintenance hemodialysis (MHD), but optimal dose of cholecalciferol is unclear.
Materials and Methods:
A total of 45 consenting patients were randomized to intervention and control groups. In the intervention group, patients (n = 35) with serum 25-hydroxy vitamin D (25(OH)D) < 30 ng/mL (n = 33), received oral cholecalciferol 60,000 units/week for 6 weeks. The serum levels of 25(OH)D, calcium, phosphorus, albumin, and parathyroid hormone (PTH) were measured at 0, 6, and 12 weeks. In the control group (n = 10), these were estimated at 0 and 6 weeks.
Results:
In the intervention group, 25/35 patients completed the supplementation at 6 weeks and 20/35 were available at 12 weeks. The mean baseline level of 25(OH)D was 9.59 ± 7.59 ng/mL, and after 6 weeks 19.51 ± 4.27 ng/mL, mean increase being 9.99 ± 6.83 ng/mL, which was highly significant (P < 0.0001). After discontinuing supplementation at 6 weeks, serum 25(OH)D level dropped significantly from 6 to 12 weeks [−2.84 ± 6.25 ng/mL (P = 0.04)]. However, it was still significantly higher at 12 weeks (16.08 ± 8.27 ng/mL) as compared with the baseline. PTH and calcium did not change significantly with supplementation. The change in serum 25(OH)D level from baseline to 6 weeks in the intervention group was inversely related to baseline 25(OH)D levels and patient's weight. In the control group, change in 25(OH)D from baseline to 6 weeks was not significant.
Conclusion:
Supplementation with cholecalciferol 60,000 unit/week for 6 weeks was insufficient to achieve optimal levels of 25(OH)D in Indian patients with CKD on MHD.
doi:10.4103/2230-8210.139227
PMCID: PMC4171888  PMID: 25285282
Cholecalciferol; chronic kidney disease; hemodialysis; India; vitamin D hemodialysis
12.  Vitamin D Deficiency in Postmenopausal Women – Biological Correlates 
Mædica  2014;9(4):316-322.
Introduction:
Low vitamin D (VD) is associated with secondary hyperparathyroidism and both contribute to deleterious consequences (reduced bone mineral density (BMD), risk of fractures and falls).
Objective:
To study the VD status and biological correlates in a group of postmenopausal women.
Material and methods:
We studied 123 postmenopausal women evaluated in the C.I.Parhon National Institute of Endocrinology, the Pituitary and Neuroendocrine Diseases department. All cases had been reffered for the evaluation of BMD by the general practitioner. The evaluation included serum measurements of total and ionised calcium, phosphorus, alkaline phosphatase (ALP), 25 hydroxi vitaminD (25OHD), parathyroid hormone (PTH), osteocalcin, betacrosslaps. Central DXA osteodensitometry was performed.
Results:
91.9% of cases had 25OHD serum levels below 30 ng/ml (74.8% had VD deficiency, 17.1% VD insufficiency). Only 8.1% had sufficient VD levels. A history of fragility fractures was present in 45.83% of the osteoporotic patients, 27.27% of the osteopenic ones and 15.15% of the women with normal BMD.
32 women (26%) were on VD supplementation at the time of evaluation. Among these subjects, the 25OHD level was significantly higher in those with prior fragility fractures (p=0.018) and osteoporosis (p=0.008).
25OHD concentration negatively correlated with PTH, alkaline phosphatase (ALP) and osteocalcin. The bone markers evaluated had a significant inverse correlation with the radius BMD, T and Z scores (p=0.004).
27.17% of the cases with VD deficiency had secondary hyperparathyroidism. The 25OHD concentration was significantly lower in these cases (p=0.000).
Conclusions:
VD insufficiency is widely prevalent but still under-recognized and under-treated, possibly leading to secondary hyperparathyroidism. The compliance to VD supplementation is lower in subjects without osteoporosis or fragility fractures. Primary prevention measures should be more actively implemented.
PMCID: PMC4316873
vitamin D; deficiency; postmenopausal; secondary hyperparathyroidism
13.  Vitamin D deficiency in hemodialysis patients 
Background:
Vitamin D [(25(OH)D] deficiency and insufficiency is common in patients with chronic kidney disease (CKD). 25(OH)D has been found to have beneficial effects on bone, cardiovascular and immune functions. There are little data about vitamin D levels in Indian patients on dialysis. This study was undertaken to determine the vitamin D status of Indian CKD patients on hemodialysis.
Materials and Methods:
We included 45 patients on maintenance hemodialysis coming to Medanta, Medicity, Gurgaon. 25(OH)D levels were measured with radioimmunoassay (Diasorin) method and parathyroid hormone (PTH) was measured using electrochemiluminiscence immunoassay (ECLIA).
Results:
The mean age of patients was 55 ± 13 years. 32/45 (71%) were males. 23/45 (51%) were diabetics. The median duration of hemodialysis was 5.5 months (range 1–74 months). 33/45 (74%) patients were on thrice weekly hemodialysis. The mean level of vitamin D was 10.14 ± 8.7 ng/ml. Majority of the patients [43/45 (95.5%)] were either vitamin D deficient or had insufficient levels. 40/45 (88.9%) were vitamin D deficient (levels <20 ng/ml); of these, 29/40 (64.4%) had severe vitamin D deficiency (levels <10 ng/ml) and 3/45 (6.7%) had insufficient levels (20–30 ng/ml) of vitamin D. Only 2/45 (4.4%) patients had normal levels of vitamin D. 23/45 (51%) of patients were receiving calcitriol. The mean levels of serum calcium, phosphorus, alkaline phosphatase, and albumin were 8.8 ± 0.64 mg/dl, 5.0 ± 0.7 mg/dl, 126 ± 10.3 IU/l and 3.6 ± 0.62 g/dl, respectively. PTH levels ranged from 37 to 1066 pg/ml, and the median was 195.8 pg/ml. There was a weak correlation between 25(OH)D levels and weight, sex, hemoglobin, albumin, alkaline phosphatase, and presence of diabetes. There was, however, no correlation with duration of dialysis or PTH levels.
Conclusion:
Vitamin D deficiency and insufficiency are universal in our hemodialysis patients, with severe vitamin D deficiency in two-third of patients.
doi:10.4103/2230-8210.93749
PMCID: PMC3313747  PMID: 22470866
Chronic kidney disease; hemodialysis; vitamin D
14.  Circulating Insulin-like Growth Factor Binding Protein-4 (IGFBP-4) is not Regulated by Parathyroid Hormone and Vitamin D in vivo: Evidence from Children with Rickets 
Objective: Insulin-like growth factor binding protein-4 (IGFBP-4), inhibits IGF actions under a variety of experimental conditions. Parathyroid hormone (PTH), 1.25-hydroxy(OH)vitamin D, IGF-I, IGF-II and transforming growth factor (TGF)-b are the major regulators of IGFBP-4 production in vitro. However, little is known about the in vivo regulation of circulating IGFBP-4 in humans.
Methods: We measured serum concentrations of calcium (Ca), phosphorus (P), alkaline phosphatase (ALP), PTH, vitamin D, IGF-I, IGFBP-3, and IGFBP-4 in infants (n=22) with nutritional rickets before and after treatment of rickets with vitamin D (300 000 U single dose po).
Results: The mean±SD age of the patients was 1.3±1.6 years (range 0.2-3). Serum Ca and P increased, whereas ALP and PTH decreased after treatment (Ca from 6.6±1.4 to 9.5±1.6 mg/dL, P from 3.9±1.4 to 5.4±0.8 mg/dL, ALP from 2590±2630 to 1072±776 IU/mL and PTH from 407±248 to 27.4±20.8 ng/dL, respectively). Vitamin D levels were low (7.8±2.5 ng/mL) and increased after treatment (18.1±4.0 ng/mL, p<0.001). Serum IGF-I and IGFBP-3 levels both increased after treatment (IGF-I: 13.5±12.2 vs. 23.7±14.2 ng/mL, p<0.001 and IGFBP-3: 1108±544 vs. 1652±424 ng/mL, p<0.001). However, serum IGFBP-4 levels did not change significantly after treatment (18.8±8.0 vs. 21.5±4.8 ng/mL). No correlation between PTH and IGF-I, IGFBP-3 or IGFBP-4 was detected. Significant correlations were observed between PTH and ALP (r=0.53, p<0.05), and between IGF-I and IGFBP-3 (r=0.46, p<0.05).
Conclusion: The results demonstrate that contrary to in vivo studies, circulating IGFBP-4 levels are not influenced by secondary hyperparathyroidism in vitamin D deficiency rickets since IGFBP-4 levels did not change after normalization of PTH with vitamin D treatment.
Conflict of interest:None declared.
doi:10.4274/jcrpe.v2i1.17
PMCID: PMC3005664  PMID: 21274331
Vitamin D; rickets; IGF-I; IGFBP-3; IGFBP-4; PTH; Bone
15.  Urinary cyclic AMP analyzed as a function of the serum calcium and parathyroid hormone in the idfferential diagnosis of hypercalcemia. 
Urinary cyclic AMP (UcAMP) appropriate for the serum calcium concentration was determined in normal subjects during the base-line state and during alteration in their serum calcium concentrations by saline and calcium infusions. This was compared to the UcAMP in 76 patients with hypercalcemia and 5 patients with hypocalcemia. In 54 of 56 patients with primary hyperparathyroidism, the UcAMP was inappropriately high for their serum calcium concentration, the 2 exceptions having renal failure. In four patients with vitamin D intoxication, sarcoidosis, milkalkali syndrome, and thiazide-induced hypercalcemia and in five patients with hypocalcemia due to hypoparathyroidism, the UcAMP was appropriately low for their serum calcium concentration. In 16 patients with nonparathyroid neoplasms, 10 had UcAMP levels that were inappropriately high suggesting ectopic parathyroid hormone (PTH)-mediated hypercalcemia and 6 had UcAMP levels that were appropriately low suggesting that their hypercalcemia was due to osteolytic factors other than PTH. Correlations between UcAMP, serum calcium concentration, and carboxyl-terminal immunoreactive PTH suggest that random UcAMP is a sensitive accurate reflection of circulating biologically active PTH. If there is adequate renal function (serum creatinine concentration less than 2.0 mg/dl), a random UcAMP expressed as mumol/g creatinine and analyzed as a function of the serum calcium concentration completely separates patients with PTH and non-PTH-mediated hypercalcemia.
PMCID: PMC333327  PMID: 187621
16.  Serum Intact Parathyroid Hormone Level After Total Thyroidectomy or Total Thyroidectomy Plus Lymph Node Dissection for Thyroid Nodules: Report From 296 Surgical Cases 
Background
Transient hypocalcemia is one of the postoperative complications of thyroidectomy for thyroid nodules, and intraoperative and postoperative intact parathyroid hormone (iPTH) assays are used to predict postoperative hypocalcemia.
Objectives
The current study was conducted to evaluate a single serum iPTH measurement on postoperative day 1 (POD 1) as a means to predict hypocalcemia occurrence after total thyroidectomy (TT).
Patients and Methods
The subjects consisted of 36 patients who underwent TT and 260 patients who underwent TT plus lymph node (LN) dissection for thyroid nodules treatment. The TT performance procedure to prevent postoperative hypoparathyroidism combines parathyroid gland preservation in situ with autotransplantation of resected or devascularized parathyroid glands. The patients’ serum iPTH level was measured on POD 1, and their serum calcium level was measured on POD 1 and on POD 3 while they were still inpatients. The serum iPTH level was subequently measured at each outpatient clinic visit until it recovered to the normal range.
Results
Hypoparathyroidism after TT and TT plus LN dissection was ultimately diagnosed in a total of 229 patients, and in 69 of them hypocalcemia was diagnosed on POD 1. All of the 69 patients diagnosed with hypocalcemia received calcium and vitamin D supplementation therapy. The serum iPTH level of 67 of 229 patients was within normal range on POD 1, and four of them developed hypocalcemia on POD 1. Permanent hypoparathyroidism developed in 37 of 296 patients after undergoing TT or TT plus LN dissection for thyroid nodules in the hospital.
Conclusions
A single serum iPTH measurement on POD 1 is useful to determine whether or not to start calcium and vitamin D supplementation in order to maintain normocalcemia after surgery.
doi:10.5812/ijem.3462
PMCID: PMC3693643  PMID: 23843829
Hypoparathyroidism; Hypocalcemia; Thyroidectomy, Thyroid Nodule; Parathyroid
17.  Evidence that blood ionized calcium can regulate serum 1,25(OH)2D3 independently of parathyroid hormone and phosphorus in the rat. 
Journal of Clinical Investigation  1985;76(4):1599-1604.
This study asks whether arterial blood ionized calcium concentration (Ca++) can regulate the serum level of 1,25-dihydroxy-vitamin D3 [1,25(OH)2D3] independently of serum phosphorus and parathyroid hormone (PTH). We infused either PTH (bovine 1-34, 10 U/kg body wt/h) or saline into awake and unrestrained rats for 24 h, through a chronic indwelling catheter. PTH raised total serum calcium and arterial blood ionized calcium, yet serum 1,25(OH)2D3 fell from 35 +/- 6 (mean +/- SEM, n = 10) with saline to 12 +/- 3 pg/ml (n = 11, P less than 0.005 vs. saline). To determine if the decrease in serum 1,25(OH)2D3 was due to the elevated Ca++, we infused PTH into other rats for 24 h, along with varying amounts of EGTA. Infusion of PTH + 0.67 micron/min EGTA reduced Ca++, and 1,25(OH)2D3 rose to 90 +/- 33 (P less than 0.02 vs. PTH alone). PTH + 1.00 micron/min EGTA lowered Ca++ more, and 1,25(OH)2D3 increased to 148 +/- 29 (P less than 0.01 vs. saline or PTH alone). PTH + 1.33 micron/min EGTA lowered Ca++ below values seen with saline or PTH alone, and 1,25(OH)2D3 rose to 267 +/- 46 (P less than 0.003 vs. all other groups). Thus, during PTH infusion lowering Ca++ with EGTA raised 1,25(OH)2D3 progressively. There were no differences in serum phosphorus concentration or in arterial blood pH in any group infused with PTH. The log of serum 1,25(OH)2D3 was correlated inversely with Ca++ in all four groups infused with PTH (r = -0.737, n = 31, P less than 0.001), and also when the saline group was included (r = -0.677, n = 41, P less than 0.001). The results of this study indicate that serum 1,25(OH)2D3 may be regulated by Ca++ independent of PTH and serum phosphorus levels in the rat. Since 1,25(OH)2D3 regulates gastrointestinal calcium absorption, there may be direct feedback control of 1,25(OH)2D3, by its regulated ion, Ca++.
PMCID: PMC424140  PMID: 3840495
18.  Elevations in Serum and Urinary Calcium with Parathyroid Hormone (1–84) with and without Alendronate for Osteoporosis 
Context
The effect of PTH therapy on serum and urinary calcium levels and the risk of hypercalcemia or hypercalciuria has not been formally evaluated.
Objective
The objective was to examine changes in serum and urinary calcium associated with PTH(1–84) therapy in the PaTH trial and the extent to which a defined algorithm resolved the elevated values.
Design, Setting, Participants, and Intervention
A total of 178 postmenopausal women were randomized to PTH(1–84) either alone or in combination with alendronate during the first year of the PaTH study.
Main Outcome Measure(s)
The main outcome measures were fasting serum calcium at baseline and 1, 3, and 12 months and 24-h urinary calcium at baseline and 3 months.
Results
In 14% of participants, serum calcium more than 10.5 mg/dl (>2.6 mmol/liter) developed. Following the defined algorithm, 58% of elevated measurements were normal on repeat testing; 38% required discontinuation of calcium and vitamin D supplementation, and one necessitated a decrease in PTH injection frequency to normalize serum calcium. One participant developed transient hypercalcemia between study visits and required hospitalization; the episode resolved with iv hydration and PTH discontinuation. Baseline characteristics associated with the development of hypercalcemia were serum calcium [relative hazards = 1.9 per 0.5 mg/dl (0.12 mmol/liter); 95% confidence interval = 1.1–3.2] and serum 1,25-dihydroxyvitamin D [relative hazard = 1.9 per 10 pg/ml (26 pmol/liter); 95% confidence interval = 1.2–3.1]. Fifteen women (8%) developed hypercalciuria [urinary calcium > 400 mg (100 mmol)/24 h or calcium/creatinine ratio > 0.4]; 80% of cases resolved after discontinuing calcium and vitamin D, 13% without intervention, and one after PTH injection frequency was decreased. Higher baseline urinary calcium excretion was associated with development of hypercalciuria [relative hazard = 1.5 per 50 mg/d (12.5 mmol/d); 95% confidence interval = 1.2–4.0]. Proportions of patients with elevated serum and urinary calcium were similar on single and combination therapy.
Conclusions
The frequency of episodic hypercalcemia or hypercalciuria in the PaTH trial was 21%. Episodes were generally mild, and nearly all cases resolved spontaneously or with discontinuation of calcium and vitamin D. The algorithms used to address hypercalcemia and hypercalciuria in the PaTH trial proved effective in safely resolving clinical episodes of increased urinary or serum calcium and might therefore be helpful to clinicians caring for patients on PTH.
doi:10.1210/jc.2006-1788
PMCID: PMC3746103  PMID: 17164314
19.  Biochemical Markers of Bone Turnover Associated with Calcium Supplementation in Children with Juvenile Rheumatoid Arthritis 
Arthritis and rheumatism  2008;58(12):3932-3940.
OBJECTIVE
To determine the effects of calcium supplementation on bone physiology in corticosteroid-free juvenile rheumatoid arthritis (JRA) children by measuring serum and urinary bone-related hormones, minerals, bone formation and resorption markers.
METHODS
In this double-blind trial, patients were randomized to receive daily oral supplementation of 1000 mg of calcium and 400 IU vitamin D or placebo and 400 IU vitamin D for 24 months. The physiologic effect of calcium supplementation on bone physiology was followed periodically using markers of bone turnover.
RESULTS
198 patients met inclusion criteria and were followed in the study. At baseline there were no differences in markers of bone turnover between the two groups. Subjects with <4 active joints had higher serum calcium and higher PTH. Individuals receiving calcium with <4 active joints had lower osteocalcin. At follow-up1,25 (OH)2 vitamin D, PTH, osteocalcin and urine phosphorus were lower in the calcium supplementation group. Hypercalciuria noted with urine Ca/Creatinine were not noted on 24-hour urine studies.
CONCLUSIONS
Markers of bone physiology were significantly decreased in children with JRA receiving calcium supplementation. The physiologic changes were noted as early as 12 months into calcium supplementation. The hypercalciuria noted on spot testing did not correlate with further evaluation nor did it lead to renal pathology. These findings suggesting that the calcium supplementation met physiologic needs and caused an increased calcium loss in urine.
doi:10.1002/art.24041
PMCID: PMC2630222  PMID: 19035501
Juvenile rheumatoid arthritis; bone markers; biochemical markers; bone turnover
20.  Hypoparathyroidism: clinical features, skeletal microstructure and parathyroid hormone replacement 
Objective
Hypoparathyroidism is a disorder in which parathyroid hormone is deficient in the circulation due most often to immunological destruction of the parathyroids or to their surgical removal. The objective of this work was to define the abnormalities in skeletal microstructure as well as to establish the potential efficacy of PTH(1-84) replacement in this disorder.
Subjects and methods
Standard histomorphometric and μCT analyses were performed on iliac crest bone biopsies obtained from patients with hypoparathyroidism. Participants were treated with PTH(1-84) for two years.
Results
Bone density was increased and skeletal features reflected the low turnover state with greater BV/TV, Tb. Wi and Ct. Wi as well as suppressed MS and BFR/BS as compared to controls. With PTH(1-84), bone turnover and bone mineral density increased in the lumbar spine. Requirements for calcium and vitamin D fell while serum and urinary calcium concentrations did not change.
Conclusion
Abnormal microstructure of the skeleton in hypoparathyroidism reflects the absence of PTH. Replacement therapy with PTH has the potential to correct these abnormalities as well as to reduce the requirements for calcium and vitamin D.
PMCID: PMC3702727  PMID: 20485912
Calcium; hypoparathyroidism; parathyroid hormone; vitamin D; bone density
21.  Acetate free citrate-containing dialysate increase intact-PTH and BAP levels in the patients with low intact-PTH 
BMC Nephrology  2013;14:18.
Background
Recently, acetate-free citrate containing dialysate (A(−)D) was developed. We have already reported about the significant effect of A(−)D on metabolic acidosis, anemia, and malnutrition in maintenance hemodialysis (MHD) patients. In this study, we compared the effect of A(−)D and acetate containing dialysate (A(+)D) on serum calcium and intact-parathyroid hormone (int-PTH) levels.
Method
Single session study: Seventeen patients were treated with A(+)D in one session and also treated with A(−)D in another session. Serum levels of pH, HCO3-, total (t)-calcium, ionized (i)-calcium, and int-PTH were evaluated at the beginning and the end of each session. Cross over study: A total of 29 patients with MHD were treated with A(+)D for 4 months, switched to A(−)D for next 4 months, and returned to A(+)D for the final 4 months.
Results
In single session study, serum i-calcium and t-calcium levels significantly increased, and int-PTH levels decreased after HD with A(+)D, whereas HD with A(−)D did not affect iCa and int-PTH. In cross over study, if all patients were analyzed, there was no significant difference in serum int-PTH or bone alkaline phosphatase (BAP) levels during each study period. In contrast, in the patients with low int-PTH (<60 pg/mL), serum levels of int-PTH and BAP were significantly increased during the A(−)D, without significant changes in serum t-calcium or i-calcium levels.
Conclusion
A(−)D containing citrate could affect calcium and PTH levels, and, in 4 month period of crossover study, increased int-PTH levels pararelled with increasing BAP levels, exclusively in MHD patients with low int-PTH levels.
doi:10.1186/1471-2369-14-18
PMCID: PMC3583681  PMID: 23327614
Acetate free citrate-containing dialysate; Low intact-parathyroid hormone; Bone alkaline phosphatase; Total calcium; Ionized calcium
22.  The Effect of Tenofovir on Vitamin D Metabolism in HIV-Infected Adults Is Dependent on Sex and Ethnicity 
PLoS ONE  2012;7(9):e44845.
Background
Tenofovir has been associated with renal phosphate wasting, reduced bone mineral density, and higher parathyroid hormone levels. The aim of this study was to carry out a detailed comparison of the effects of tenofovir versus non-tenofovir use on calcium, phosphate and, vitamin D, parathyroid hormone (PTH), and bone mineral density.
Methods
A cohort study of 56 HIV-1 infected adults at a single centre in the UK on stable antiretroviral regimes comparing biochemical and bone mineral density parameters between patients receiving either tenofovir or another nucleoside reverse transcriptase inhibitor.
Principal Findings
In the unadjusted analysis, there was no significant difference between the two groups in PTH levels (tenofovir mean 5.9 pmol/L, 95% confidence intervals 5.0 to 6.8, versus non-tenofovir; 5.9, 4.9 to 6.9; p = 0.98). Patients on tenofovir had significantly reduced urinary calcium excretion (median 3.01 mmol/24 hours) compared to non-tenofovir users (4.56; p<0.0001). Stratification of the analysis by age and ethnicity revealed that non-white men but not women, on tenofovir had higher PTH levels than non-white men not on tenofovir (mean difference 3.1 pmol/L, 95% CI 5.3 to 0.9; p = 0.007). Those patients with optimal 25-hydroxyvitamin D (>75 nmol/L) on tenofovir had higher 1,25-dihydroxyvitamin D [1,25(OH)2D] (median 48 pg/mL versus 31; p = 0.012), fractional excretion of phosphate (median 26.1%, versus 14.6; p = 0.025) and lower serum phosphate (median 0.79 mmol/L versus 1.02; p = 0.040) than those not taking tenofovir.
Conclusions
The effects of tenofovir on PTH levels were modified by sex and ethnicity in this cohort. Vitamin D status also modified the effects of tenofovir on serum concentrations of 1,25(OH)2D and phosphate.
doi:10.1371/journal.pone.0044845
PMCID: PMC3440360  PMID: 22984574
23.  Nutritional Status of Vitamin D and the Effect of Vitamin D Supplementation in Korean Breast-fed Infants 
We investigated the vitamin D status and the effect of vitamin D supplementation in Korean breast-fed infants. The healthy term newborns were divided into 3 groups; A, formula-fed; B, breast-fed only; S, breast-fed with vitamin D supplementation. We measured serum concentrations of vitamin D (25OHD3), calcium (Ca), phosphorus (P), alkaline phosphatase (AP), intact parathyroid hormone (iPTH) and bone mineral density (BMD) at 6 and 12 months of age. Using questionnaires, average duration of sun-light exposure and dietary intake of vitamin D, Ca and P were obtained. At 6 and 12 months of age, 25OHD3 was significantly higher in group S than in group B (P<0.001). iPTH was significantly lower in group S than in group B at 6 months (P=0.001), but did not differ at 12 months. Regardless of vitamin D supplementation, BMD was lower in group B and S than in group A (P<0.05). Total intake of vitamin D differed among 3 groups (P<0.001, A>S>B), but total intake of Ca and P were higher in group A than in group B and S (P<0.001). In conclusion, breast-fed infants show lower vitamin D status and bone mineralization than formula-fed infants. Vitamin D supplementation (200 IU/day) in breast-fed infants increases serum 25-OH vitamin D3, but not bone mineral density.
doi:10.3346/jkms.2010.25.1.83
PMCID: PMC2800022  PMID: 20052352
Vitamin D; Nutritional Status; Bone Density; Vitamin D Deficiency; Dietary Supplements; Breast feeding; Infant
24.  Prevalence of 25(OH) Vitamin D Insufficiency and Deficiency in Pediatric Patients on Chronic Dialysis 
♦ Background: 25(OH) Vitamin D [25(OH)D] is the major circulating form of vitamin D and the parameter used to reflect vitamin D status. Patients with chronic kidney disease (CKD) are likely to have low levels of 25(OH)D, and recent observations have linked suboptimal vitamin D status with adverse cardiovascular outcomes, inflammation, insulin resistance, and the rate of progression of renal insufficiency. Little is known about the magnitude of vitamin D deficiency in pediatric patients with stage 5 CKD on chronic dialysis.
♦ Objectives: The aim of the present cross-sectional study was to assess the prevalence of abnormal vitamin D status in children on chronic dialysis.
♦ Methods: Serum 25(OH)D, 1,25(OH)2 vitamin D [1,25(OH)2D], calcium, phosphorus, and parathyroid hormone (PTH) were evaluated in 59 pediatric patients on chronic dialysis. Weekly renal Kt/V and creatinine clearance (CCr) were evaluated as parameters reflecting residual renal function. In these patients, serum 25(OH)D concentrations less than 10 ng/mL were considered deficiency and concentrations of 10 - 30 ng/mL were considered insufficiency.
♦ Results: Of the 59 pediatric patients (mean age: 14.4 ± 5.1 years), 51 (86.4%) were on peritoneal dialysis (PD), and 8 (13.6%) were on hemodialysis. Vitamin D deficiency was found in 32.2% of the patients (n = 19), and vitamin D insufficiency, in 50.8% (n = 30). Patients with serum 25(OH)D concentrations less than 30 ng/mL were older than those with normal 25(OH)D concentrations (15.4 ± 4.5 years vs 9.2 ± 5.1 years, p = 0.000). Patients with 25(OH) D concentrations less than 30 ng/mL had higher PTH levels than did those with normal 25(OH)D concentrations (349.5 ± 318.3 pg/mL vs 142.5 ± 116.9 pg/mL, p = 0.001). In the univariate analysis, there was no correlation between serum 25(OH)D and serum 1,25(OH)2D (r = 0.242, p = 0.064), calcium (r = 0.108, p = 0.415), phosphorus (r = -0.050, p = 0.706), or body mass index (r = -0.046, p = 0.729). In PD patients, serum 25(OH)D was positively correlated with weekly renal Kt/V (r = 0.385, p = 0.005) and CCr (r = 0.443, p = 0.001). In addition, serum 25(OH)D and serum albumin were positively correlated (r = 0.297, p = 0.035) in the PD patients.
♦ Conclusions: The present study found a high prevalence of 25(OH)D deficiency and insufficiency in children on chronic dialysis. Serum 25(OH)D was associated with residual renal function in children on PD. Further studies to evaluate the consequences of vitamin D deficiency and the impact of therapeutic interventions are needed in pediatric CKD patients.
doi:10.3747/pdi.2011.00246
PMCID: PMC3707718  PMID: 23209039
Chronic kidney disease; 25(OH) vitamin D deficiency; chronic dialysis; residual renal function
25.  Mineral bone disease in maintenance hemodialysis patients: Association with morbidity and mortality 
Indian Journal of Nephrology  2014;24(5):302-307.
There is a paucity of data on mineral bone disease in maintenance hemodialysis (MHD) patients from India. This retrospective analysis was undertaken on 858 (males: 599; females: 259) patients from two medical centers on MHD from 1998 to 2010. Age, gender, months on dialysis, hours per session of dialysis, hemoglobin, serum calcium, inorganic phosphorus, intact parathyroid hormone (iPTH), urine output, erythropoietin dosage per week, blood sugar, blood pressure, urea reduction rate, gain in fluid and fluid removed per session, serum albumin, alkaline phosphatase, vitamin D level, supplemental vitamin D and use of phosphate binder for therapy were documented. Overall, 191 patients died (22%) during the observation period. There was an 86% patient survival rate at 1 year on dialysis and an overall predicted 3-year survival rate of 78%. A relatively higher iPTH (P = 0.012), a need for vitamin D supplementation (P = 0.003), less hours on dialysis per session (P = 0.046) and a non-vegetarian diet (P = 0.022) were significantly associated with mortality.
doi:10.4103/0971-4065.132988
PMCID: PMC4165055  PMID: 25249720
Asia; mineral bone disease; hemodialysis

Results 1-25 (1425272)