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1.  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.
PMCID: PMC3005664  PMID: 21274331
Vitamin D; rickets; IGF-I; IGFBP-3; IGFBP-4; PTH; Bone
2.  The Effect of Vitamin D Treatment on Serum Adiponectin Levels in Children with Vitamin D Deficiency Rickets 
Objective: Adiponectin and its receptors are known to be expressed in osteoblasts and may have important functions in normal bone cells. The aim of this study was to investigate the effect of vitamin D therapy on serum adiponectin levels in children with vitamin D deficiency rickets (VDDR).
Methods: 21 patients with VDDR were included in the study. Patients were treated with 300,000 U D3 (IM) and calcium lactate (50mg/kg/ day, PO, for 10 days). Anthropometric parameters and serum biochemical markers including calcium (Ca), phosphorus (P), alkaline phosphatase (ALP), intact parathormone (iPTH), 25-hydroxyvitamin D (25(OH)D), and adiponectin levels were measured before and after one month of therapy.
Results: Weight and length, but not BMI, increased significantly after treatment. Serum 25(OH)D level increased significantly after treatment, while serum adiponectin level decreased (4.21±1.84 vs 52.73±17.63 ng/ml, p<0.000; 150.1±66.14 vs 84.29±9.06 mg/ml, p<0.000, respectively). No significant correlations were found between serum adiponectin and 25(OH)D levels before and after treatment or between delta adiponectin concentrations and delta 25(OH)D levels.
Conclusion: Serum adiponectin levels are increased in patients with VDDR, a finding which is probably related to increased osteoblastic activity.
Conflict of interest:None declared.
PMCID: PMC3005753  PMID: 21274306
treatment; Vitamin D; Adiponectin; rickets

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