The 24-h urine protein-to-creatinine ratio is the gold standard in evaluating proteinuria in lupus nephritis; however, the urine collection is inconvenient to the patient. Random spot urine protein-to-creatinine ratios, although convenient, have poor agreement with the 24-h ratios in these patients. Here, we sought to define a timed collection interval providing accurate and precise data and patient convenience. Urine from 41 patients, in 2 medical centers, with biopsy-proven lupus nephritis was collected at 6-h intervals for 24 h. The protein-to-creatinine ratio of each short collection was then compared with that of a 24-h collection made by combining the 6-h samples. A first morning void and spot urine samples were collected before and after the 24-h collection, respectively. There was significant diurnal variation with peak proteinuria at 6–12 h and nadir at 18–24 h. Each 6-h collection showed excellent correlation and concordance with the 24-h protein-to-creatinine ratio, but the 12–24-h interval had the best agreement. In contrast to the random spot urines, the first morning void also had excellent correlation and concordance, but underestimated the 24-h protein-to-creatinine ratio. Our study shows that a 12-h overnight urine collection is the best surrogate, with excellent agreement with the 24-h protein-to-creatinine ratio, and it is convenient for patients. There was little variability between centers, an important feature for clinical trials.
glomerulonephritis; lupus nephritis; nephritis; proteinuria systemic lupus erythematosus
Few studies have shown that calculation of protein/creatinine ratio in a spot urine sample correlates well with the 24-hour urine collection. A study was conducted to compare the accuracy of a spot urinary protein/creatinine ratio (P/C ratio) and urinary dipstick (albustix) with the 24-hour urine protein (24-HUP). Fifty samples from 26 patients were collected. This included a 24-hour urine sample followed by the next voided spot sample. The protein/creatinine ratio was calculated and dipstick (albustix) was performed on the spot sample. This was compared with the 24-hour urine protein excretion. The correlation between the three samples was statistically highly significant (p=<0.001) for all levels of proteinuria. The normal value of protein/creatinine ratio in Indian children was also estimated on 100 normal children attending the OPD and was calculated to be 0.053 (S.E of mean±0.003).
Proteinuria; spot urine sampling; nephrotic syndrome; mean
The objective of this study was to determine the impact of lupus nephritis disease activity on maternal and fetal outcomes in pregnant patients with systemic lupus erythematosus (SLE).
Medical records of all pregnant patients with SLE treated at our institution between 1976 and 2007 were reviewed. All patients met American College of Rheumatology classification criteria for SLE. Demographic data, history of lupus nephritis, nephritis disease activity, and maternal and fetal outcomes of pregnancy were abstracted. Active lupus nephritis was defined as the presence of proteinuria > 0.5 g/day and/or active urinary sediment with or without an elevation in serum creatinine (Cr). Quiescent lupus nephritis was confirmed in the presence of proteinuria < 0.5 mg/day and inactive urinary sediment.
We identified fifty-eight patients with ninety pregnancies. Compared to pregnancies in SLE patients without renal involvement (n=47), pregnancies in patients with active lupus nephritis (n=23) were associated with a higher incidence of maternal complications (57% vs. 11%, p<0.001), whereas those with quiescent lupus nephritis (n=20) were not (35% vs. 11%, p=0.10). Women with active lupus nephritis were more likely to deliver preterm than women without lupus nephritis, median of 34 weeks vs. 40 gestational weeks, respectively (p=0.002), and were more likely to suffer fetal loss (35% vs 9%, p=0.031).
Active, but not quiescent, lupus nephritis during pregnancy is associated with a higher incidence of maternal and fetal complications compared to pregnancies in SLE patients without renal involvement.
Pregnancy; Systemic lupus erythematosus; Lupus nephritis; Pregnancy outcomes; Preeclampsia
Measurements of protein/creatinine ratio in 'spot' urine samples were compared with measurements of 24 hour quantitative proteinuria and side room 'dipstick' testing in 104 samples from 90 patients presenting consecutively to a rheumatology unit. Linear regression analysis showed a highly significant correlation between the random urinary protein/creatinine ratio and total protein excretion in 24 hour urine samples (r = 0.92, p less than 0.001, y = 6.55x + 0.04). Although an approximation of 24 hour urinary protein excretion could have been made from the regression line: 24 hour urine protein = 6.55 x protein/creatinine ratio + 0.04 (g/l), there was a wide scatter of values, particularly in patients with greater than 1 g/24 h urinary protein excretion. Nevertheless, significant proteinuria (greater than 300 mg/24 h) could have been confirmed or excluded with a sensitivity and specificity of 97% by adopting random protein/creatinine values of less than 0.04 as 'normal'. Specificity and sensitivity could have been increased to 100%, however, by excluding patients with values lying between 0.01 and 0.10 as all the false negatives (n = 3) and false positives (n = 3) lay within this range. In comparison, dipstick testing, although 100% sensitive, had a poor specificity due to the high false positive rate (40/83 (48%] in patients with 1+ to 3+ readings. Assessment of random urinary protein/creatinine ratio may obviate the need for 24 hour urine collections in the initial assessment of suspected proteinuria. A wider application of this technique seems indicated in view of the obvious advantages in terms of cost, time, and patient convenience.
Objective To determine the diagnostic accuracy of two “spot urine” tests for significant proteinuria or adverse pregnancy outcome in pregnant women with suspected pre-eclampsia.
Design Systematic review and meta-analysis.
Data sources Searches of electronic databases 1980 to January 2011, reference list checking, hand searching of journals, and contact with experts.
Inclusion criteria Diagnostic studies, in pregnant women with hypertension, that compared the urinary spot protein to creatinine ratio or albumin to creatinine ratio with urinary protein excretion over 24 hours or adverse pregnancy outcome. Study characteristics, design, and methodological and reporting quality were objectively assessed.
Data extraction Study results relating to diagnostic accuracy were extracted and synthesised using multivariate random effects meta-analysis methods.
Results Twenty studies, testing 2978 women (pregnancies), were included. Thirteen studies examining protein to creatinine ratio for the detection of significant proteinuria were included in the multivariate analysis. Threshold values for protein to creatinine ratio ranged between 0.13 and 0.5, with estimates of sensitivity ranging from 0.65 to 0.89 and estimates of specificity from 0.63 to 0.87; the area under the summary receiver operating characteristics curve was 0.69. On average, across all studies, the optimum threshold (that optimises sensitivity and specificity combined) seems to be between 0.30 and 0.35 inclusive. However, no threshold gave a summary estimate above 80% for both sensitivity and specificity, and considerable heterogeneity existed in diagnostic accuracy across studies at most thresholds. No studies looked at protein to creatinine ratio and adverse pregnancy outcome. For albumin to creatinine ratio, meta-analysis was not possible. Results from a single study suggested that the most predictive result, for significant proteinuria, was with the DCA 2000 quantitative analyser (>2 mg/mmol) with a summary sensitivity of 0.94 (95% confidence interval 0.86 to 0.98) and a specificity of 0.94 (0.87 to 0.98). In a single study of adverse pregnancy outcome, results for perinatal death were a sensitivity of 0.82 (0.48 to 0.98) and a specificity of 0.59 (0.51 to 0.67).
Conclusion The maternal “spot urine” estimate of protein to creatinine ratio shows promising diagnostic value for significant proteinuria in suspected pre-eclampsia. The existing evidence is not, however, sufficient to determine how protein to creatinine ratio should be used in clinical practice, owing to the heterogeneity in test accuracy and prevalence across studies. Insufficient evidence is available on the use of albumin to creatinine ratio in this area. Insufficient evidence exists for either test to predict adverse pregnancy outcome.
Quantification of proteinuria is usually predicated upon 24-hour urine collection. Multiple factors influence urine collection and the rate of protein and creatinine excretion. Urine collection is often incomplete, and therefore creatinine and protein excretion rates are underestimated. A random urine protein-creatinine (P-C) ratio has been shown over the years to be a reliable alternative to the 24-hour collection for detection and follow up of proteinuria. However, urine protein excretion may be influenced by physical activity. We studied 48 patients with proteinuria and varying levels of physical activity to determine the correlation between the measures of urine protein excretion. The correlation coefficient (r) between 24-hour urine total protein and random urine P-C ratio was 0.75 (P < 0.01) in the overall study population, but varied according to the level of proteinuria and physical activity in a stratified analysis: r = 0.99 (P < 0.001) and r = 0.95 (P < 0.01) in bedridden patients; r = 0.44 (P = not significant [NS]) and r = 0.54 (P = NS) in semiactive patients; and r = 0.44 (P = NS) and r = 0.58 (P < 0.05) in active patients with nephrotic- (>3500 mg/day) and non-nephrotic (<3500 mg/day) range proteinuria, respectively. The correlation appeared to be stronger between random urine and 24-hour urine P-C ratio for the overall study population (r = 0.84; P < 0.001), and when stratified according to the level of proteinuria and physical activity: r = 0.99 (P < 0.001) and r = 0.92 (P < 0.01) in bedridden patients; r = 0.61 (P = NS) and r = 0.54 (P = NS) in semiactive patients; and r = 0.64 (P < 0.02) and r = 0.52 (P < 0.05) in active patients with nephrotic and non-nephrotic range proteinuria, respectively. We conclude that the random urine P-C ratio is a reliable and practical way of estimating and following proteinuria, but its precision and accuracy may be affected by the level of patient physical activity.
random urine; 24-hour urine; proteinuria; protein-creatinine ratio; activity
This study investigated the overall clinical impact of anti-α-actinin antibodies in patients with pre-selected autoimmune diseases and in a random group of anti-nuclear antibody (ANA)-positive individuals. The relation of anti-α-actinin antibodies with lupus nephritis and anti-double-stranded DNA (anti-dsDNA) antibodies represented a particular focus for the study. Using a cross-sectional design, the presence of antibodies to α-actinin was studied in selected groups, classified according to the relevant American College of Rheumatology classification criteria for systemic lupus erythematosus (SLE) (n = 99), rheumatoid arthritis (RA) (n = 68), Wegener's granulomatosis (WG) (n = 85), and fibromyalgia (FM) (n = 29), and in a random group of ANA-positive individuals (n = 142). Renal disease was defined as (increased) proteinuria with haematuria or presence of cellular casts. Sera from SLE, RA, and Sjøgren's syndrome (SS) patients had significantly higher levels of anti-α-actinin antibodies than the other patient groups. Using the geometric mean (± 2 standard deviations) in FM patients as the upper cutoff, 20% of SLE patients, 12% of RA patients, 4% of SS patients, and none of the WG patients were positive for anti-α-actinin antibodies. Within the SLE cohort, anti-α-actinin antibody levels were higher in patients with renal flares (p = 0.02) and correlated independently with anti-dsDNA antibody levels by enzyme-linked immunosorbent assay (p < 0.007) but not with other disease features. In the random ANA group, 14 individuals had anti-α-actinin antibodies. Of these, 36% had SLE, while 64% suffered from other, mostly autoimmune, disorders. Antibodies binding to α-actinin were detected in 20% of SLE patients but were not specific for SLE. They correlate with anti-dsDNA antibody levels, implying in vitro cross-reactivity of anti-dsDNA antibodies, which may explain the observed association with renal disease in SLE.
The published criteria for the proteinuria increase that constitutes a proteinuric flare in lupus glomerulonephritis (SLE GN) vary widely, likely because they are largely based on expert opinion. Ideally, the threshold for proteinuric flare should be set sufficiently high so that spontaneous variation in proteinuria does not likely explain the increase, but not so high that the patient is needlessly exposed to prolonged heavy proteinuria before a flare is declared and therapy is increased. Here we describe an evidence-based approach to setting the threshold for proteinuric flare based on quantifying the spontaneous variation in urine protein/creatinine (P/C) ratio of SLE GN patients who are not experiencing SLE flare.
SLE GN patients (N = 71) followed in the Ohio SLE Study (OSS) were tested at pre-specified bimonthly intervals within windows of ± 1 week, median follow-up > 44 mo, visit compliance > 90%. To assess spontaneous P/C ratio variation under no-flare conditions, we excluded P/C ratios measured within ± 4 month of renal flare.
For those with mean no-flare P/C ratios ≤ 0.5, the published flare thresholds are set well above the 99% confidence interval (CI) of the no-flare P/C ratios. The opposite is seen in those with patients whose mean no-flare P/C ratios ≥ 1.0.
Current thresholds for proteinuric flare appear to be set either too high or too low. A randomized trial would be needed to test whether re-setting the thresholds would result in faster remission, less therapy, and less chronic kidney disease.
Samples of protein from the urine of 23 patients with lupus nephropathy and 15 patients with proteinuria who did not have systemic lupus erythematosus (SLE) were studied for the presence of cytokines, soluble interleukin 2 receptors (sIL-2R), and free light chain immunoglobulins. The patients with lupus nephropathy were divided into two groups with active (nephritis) and inactive inflammation (nephrosis) based on the results of the analysis of urine samples and renal histology. The crude urine proteins (5 mg/ml) after precipitation by 80% ammonium sulphate from 14 patients with lupus nephritis contained higher concentrations of sIL-2R (4.88 (SEM 1.27 ng/ml) than those from nine patients with nephrosis (1.11 (0.52) ng/ml) or 15 patients without SLE (1.31 (0.87) ng/ml). The concentration of sIL-2R in protein from urine samples was not correlated with the concentration in plasma and was inversely correlated with the excretion of protein in urine over 24 hours in patients with SLE. It is suggested that, in addition to leakage from the circulation, the local production of sIL-2R by inflamed kidneys is possible. The crude proteins in urine were further fractionated by gel filtration on Sephacryl S-200. Arbitrarily, four fractions could be obtained from urine from patients with SLE but only three fractions were found in the urine of patients without SLE. Fraction IV derived from patients with nephritis or nephrosis augmented the pokeweed mitogen induced [3H]thymidine uptake of mononuclear cells. In addition, the positive rates of free kappa (kappa) (35.7%) and lambda (lambda) (42.9%) chains in proteins in urine from nephritic patients were higher than those in the other two groups. These results suggest that the severity of inflammation in the kidneys of patients with lupus can be reflected by the increased excretion of sIL-2R, free light chain immunoglobulins, and cytokine-like molecules in urine.
To evaluate relationships between vitamin D, proteinuria, and disease activity in pediatric systemic lupus erythematosus (SLE) and juvenile dermatomyositis (JDM).
Multiple linear regression was used to associate subject-reported race, sunscreen use, and vitamin D intake with physician-assessed disease activity and serum 25-hydroxyvitamin D [25(OH)D] in subjects with pediatric SLE (n = 37) or JDM (n = 21). Serum 25(OH)D was correlated with urinary vitamin D binding protein/creatinine ratio (DBP/C) and other indicators of proteinuria.
Serum 25(OH)D levels in subjects with SLE were inversely associated with the natural log of urinary DBP/C (r = −0.63, p < 0.001) and urine protein to creatinine ratio (r = −0.60, p<0.001), with an adjusted mean 10.9 (95% CI 5.1, 16.8) ng/mL decrease in 25(OH)D for those with proteinuria. Excluding subjects with proteinuria, serum 25(OH)D levels were inversely associated with disease activity in JDM, but not in SLE. Overall, 66% of all subjects were taking concurrent corticosteroids, but this was not associated with 25(OH)D levels.
Low serum 25(OH)D in patients with SLE is associated with proteinuria and urinary DBP. Vitamin D deficiency is associated with disease activity in patients with JDM and SLE; this relationship in SLE may be confounded by proteinuria.
25-hydroxyvitamin D; vitamin D binding protein
Antrodia camphorata is used in folk medicine for the treatment of inflammation syndromes and liver-related diseases in Taiwan. The goal of this study was to evaluate the efficacy of the mycelial extract of A. camphorata (ACE) for the treatment of systemic lupus erythematosus (SLE) in SLE-prone NZB/W F1 mice. After antibodies against double-stranded DNA appeared in NZB/W mice, the mice were orally administered varying dosages of ACE (100, 200 and 400 mg kg−1) for 5 consecutive days per week for 12 weeks via gavage. To assess the efficacy of ACE, we measured SLE-associated biochemical and histopathological biomarkers levels of blood urine nitrogen (BUN), blood creatinine, urine protein and urine creatinine and thickness of the kidney glomerular basement membrane by staining with periodic acid-Schiff. Antroquinonol, an active component of ACE, was investigated for anti-inflammation activity in lipopolysaccharide-induced RAW 267.4 cells. ACE at 400 mg kg−1 significantly suppressed urine protein and serum BUN levels and decreased the thickness of the kidney glomerular basement membrane. Antroquinonol significantly inhibited the production of tumor necrosis factor-α and interleukin-1β by 75 and 78%, respectively. In conclusion, ACE reduced urine protein and creatinine levels and suppressed the thickening of the kidney glomerular basement membrane, suggesting that ACE protects the kidney from immunological damage resulting from autoimmune disease.
Objective To review the spot protein:creatinine ratio and albumin:creatinine ratio as diagnostic tests for significant proteinuria in hypertensive pregnant women.
Design Systematic review.
Data sources Medline and Embase, the Cochrane Library, reference lists, and experts.
Review methods Literature search (1980-2007) for articles of the spot protein:creatinine ratio or albumin:creatinine ratio in hypertensive pregnancy, with 24 hour proteinuria as the comparator.
Results 13 studies concerned the spot protein:creatinine ratio (1214 women with primarily gestational hypertension). Nine studies reported sensitivity and specificity for eight cut-off points, median 24 mg/mmol (range 17-57 mg/mmol; 0.15-0.50 mg/mg). Laboratory assays were not well described. Diagnostic test characteristics were recalculated for a cut-off point of 30 mg/mmol. No significant heterogeneity in cut-off points was found between studies over a range of proteinuria. Pooled values gave a sensitivity of 83.6% (95% confidence interval 77.5% to 89.7%), specificity of 76.3% (72.6% to 80.0%), positive likelihood ratio of 3.53 (2.83 to 4.49), and negative likelihood ratio of 0.21 (0.13 to 0.31) (nine studies, 1003 women). Two studies of the spot albumin:creatinine ratio (225 women) found optimal cut-off points of 2 mg/mmol for proteinuria of 0.3 g/day or more and 27 mg/mmol for albuminuria.
Conclusion The spot protein:creatinine ratio is a reasonable “rule-out” test for detecting proteinuria of 0.3 g/day or more in hypertensive pregnancy. Information on use of the albumin:creatinine ratio in these women is insufficient.
Diabetic nephropathy is the major cause for chronic renal failure (CRF) and proteinuria is an independent risk factor for end stage renal disease. Hence, early identification and quantification of proteinuria is of prime importance in the diagnosis and management.
This study was conducted amongst 42 diabetic subjects from HSK hospital, Bagalkot. Twenty four-hour urine protein and random urine protein to creatinine ratio (P:C) was determined. Pearson's correlation, sensitivity, specificity, positive and negative predictive values were determined using 24-hour urinary protein as a gold standard for spot urine P:C ratio. ROC curve and area under curve was also determined using SPSS (11.5) software. All the results were expressed in mean±SD.
Forty two diabetes mellitus patients participated in this study. The average of 24 hour urinary protein was 1.6 ± 1.7 gm/day. The spot urine P:C ratio was 1.27 ± 1.55. There was a positive correlation between 24 hours urinary protein and spot urine P:C ratio (r = 0.925, p < 0.0001). The area under the ROC curve for urine P:C ratio at various cutoff was 0.947 (95% confidence interval: 0.831-0.992, p < 0.0001). The sensitivity and specificity was 80.65% and 100% respectively at P:C ratio cutoff of 0.3.
The random urine P:C ratio predicts the amount of 24-hour urinary protein excretion with high accuracy. Hence it can be used as a faster diagnostic substitute for 24-hour urinary protein estimation.
Type 2 Diabetes Mellitus; 24-Hour Urine; Urine Protein to Creatinine Ratio
Current UK guidelines for the identification, management and referral of chronic kidney disease advise an early-morning urine sample for the albumin:creatinine ratio or the protein:creatinine ratio (PCR) in order to quantify proteinuria. Estimated protein output (EPO) is an alternative and possibly better method of quantifying proteinuria which takes lean weight into consideration.
We carried out a single-centre study of 36 adult patients with proteinuric nephropathy over a period of 18 months. Urinary PCR and EPO estimates of 24-hour urine protein were compared with 24-hour urine collections by Bland-Altman analysis.
Average 24-hour urine protein was 1.6 g (range 0.2–5.1 g). Best agreement with 24-hour protein was for first-void EPO (limits of agreement 0.33–1.59) followed by a second-void EPO (0.40–1.76), then second-void PCR (0.40–2.08) and lastly first-void PCR (0.28–2.03). None of the differences between estimates of urine protein excretion and 24-hour urine protein were statistically significant. All estimates of protein output had wide confidence intervals confirming that spot urine samples, while simple and convenient to do, are imprecise measures of 24-hour urine protein excretion.
When estimating 24-hour urine protein from a spot urine sample, EPO may be marginally more accurate than PCR, and first-void urine samples slightly better than second-void urine samples, but a first- or second-void PCR will suffice in most instances.
Albumin:creatinine ratio; Albuminuria; Estimated protein output; Kidney disease; Protein:creatinine ratio; Proteinuria
To compare the urine protein–creatinine ratio with urinalysis to predict significant proteinuria (≥300 mg per day).
A total of 116 paired spot urine samples and 24-h urine collections were obtained prospectively from women at risk for preeclampsia. Urine protein–creatinine ratio and urinalysis were compared to the 24-h urine collection.
The urine protein–creatinine ratio had better discriminatory power than urinalysis: the receiver operating characteristic curve had a greater area under the curve, 0.89 (95% confidence interval (CI) 0.83 to 0.95) vs 0.71 (95% CI 0.64 to 0.77, P<0.001). When matched for clinically relevant specificity, urine protein–creatinine ratio (cutoff ≥0.28) is more sensitive than urinalysis (cutoff ≥1+): 66 vs 41%, P = 0.001 (with 95 and 100% specificity, respectively). Furthermore, the urine protein–creatinine ratio predicted the absence or presence of proteinuria in 64% of patients; urinalysis predicted this in only 19%.
The urine protein–creatinine ratio is a better screening test. It provides early information for more patients.
pregnancy; urinalysis; urine protein; creatinine ratio; proteinuria; preeclampsia; sensitivity and specificity
Kidney disease is one of the most serious manifestations of systemic lupus erythematosus (SLE). Despite the improvement in the medical care of SLE in the past two decades, the prognosis of lupus nephritis remains unsatisfactory. Besides exploring more effective but less toxic treatment modalities that will further improve the remission rate, early detection and treatment of renal activity may spare patients from intensive immunosuppressive therapies and reduce renal damage. Conventional clinical parameters such as creatinine clearance, proteinuria, urine sediments, anti-dsDNA, and complement levels are not sensitive or specific enough for detecting ongoing disease activity in the lupus kidneys and early relapse of nephritis. Thus, novel biomarkers are necessary to enhance the diagnostic accuracy and sensitivity of lupus renal disease, prognostic stratification, monitoring of treatment response, and detection of early renal flares. This paper reviews promising biomarkers that have recently been evaluated in longitudinal studies of lupus nephritis.
Twenty-four hour urinary albumin excretion (UAE) is considered as gold standard method for albuminuria measurement, but collection of 24-h urine is inconvenient. The aim of present study was to evaluate whether albumin: creatinine ratio (ACR) and urinary albumin concentration (UAC) in different spot urine samples correlate or not with 24-h UAE for screening of microalbuminuria in type 2 diabetic patients. We collected first morning void (FMV), random urine sample (RUS) and 24-h urine, separately on consecutive days from 104 type 2 diabetic patients. ACR and UAC in each spot urine sample compared with 24-h UAE with regard to Pearson correlation coefficient. Pearson’s correlation of albumin: creatinine ratio (ACR) with 24-h UAE was (r = 0.802 and 0.623) in first morning void (FMV) and random urine sample (RUS), respectively. Pearson’s correlation coefficient of urinary albumin concentration (UAC) compared with 24-h UAE was (r = 0.943 and 0.920), in FMV and RUS, respectively, P < 0.01. Results revealed that values in first morning void (FMV) were better correlated with 24-h urinary albumin excretion (UAE), than the values in random urine sample (RUS). We conclude that the first morning void (FMV) may be able to replace 24-h urine collection, preferably urinary albumin concentration (UAC) in the initial screening of microalbuminuria in diabetic patients.
Electronic supplementary material
The online version of this article (doi:10.1007/s12291-011-0136-0) contains supplementary material, which is available to authorized users.
Diabetes mellitus; Microalbuminuria; Screening; Spot urine sample; Urinary albumin concentration
Foamy urine is widely regarded as a sign of proteinuria. However, there is no objective definition of foamy urine and there are no reports on the proportion of involved patients who have overt proteinuria or microalbuminuria. We performed this study to investigate this proportion and to identify possible risk factors for these two conditions. We reviewed all new outpatients from 1 November 2011 to 30 April 2012 and identified patients complaining of foamy urine. Their demographic data and medical records were examined. In particular, we tabulated the patients' spot urinary protein to creatinine ratio, spot urinary microalbumin to creatinine ratio (ACR), blood urea nitrogen (BUN), and serum levels of creatinine (Cr), uric acid, calcium, phosphate, and glucose. In addition, we calculated estimated glomerular filtration rates (eGFRs) by using the CKD-EPI equation. We also performed risk factor analysis with the Chi-squared test and by logistic regression. Seventy-two patients (6.3% of total new outpatients) complained of foamy urine; of these, there were 59 males with a median age of 65.5 years (range, 36-87 years). Of the 72 patients, 16 (22.2%) had overt proteinuria. We found that diabetes, poor renal function (high Cr, BUN, low eGFR), increased serum phosphate, and increased serum glucose were associated with overt proteinuria. Multiple logistic regression analysis showed that serum Cr and serum phosphate were associated with overt proteinuria. The ACR was available for 38 patients, and in this subgroup, 12 (31.6%) showed microalbuminuria or overt proteinuria. In this subgroup, a high serum Cr was the only statistically significant risk factor. Among patients who complained of foamy urine, approximately 20% had overt proteinuria, and increased serum Cr and phosphate were statistically significant risk factors.
Proteinuria; Creatinine; Phosphates
Glomerulonephritis is a major cause of morbidity and mortality in patients with systemic lupus erythematosus (SLE). Deposition of autoantibodies in the glomeruli plays a key role in the development of lupus nephritis (LN). Different groups have proposed that either anti-nucleosome antibodies or antibodies that bind the intrinsic renal antigen, α-actinin, are central to the pathogenesis of LN. These theories have been based mainly on cross-sectional studies in patients and on experiments in animal models. No previous longitudinal studies have compared the relationships between levels of these antibodies and markers of renal function. We assessed how well anti-α-actinin, anti-nucleosome and anti-double-stranded DNA (anti-dsDNA) antibodies reflected renal outcome measures in patients with new-onset LN followed for up to 2 years.
Renal disease activity was monitored by measuring urine protein/creatinine ratio (PCR), serum albumin and a composite outcome of renal remission. At each time point, anti-nucleosome and anti-α-actinin antibodies were measured by enzyme-linked immunosorbent assay. High-avidity anti-dsDNA antibodies were measured using the Farrzyme assay. We analysed relationships between levels of the three antibodies and between antibody levels and renal outcome measures over time.
Levels of anti-nucleosome and anti-dsDNA were positively correlated with each other (r = 0.6, P = 0.0001) but neither correlated with anti-α-actinin level. At baseline, mean anti-nucleosome levels were higher in patients with LN than in healthy controls (0.32 versus 0.01, P < 0.001). The same was true for anti-dsDNA antibodies (0.50 versus 0.07, P < 0.001) but not for anti-α-actinin (0.33 versus 0.29). Over the follow-up period, anti-nucleosome and anti-dsDNA levels associated positively with urine PCR (P = 0.041 and 0.051, respectively) and negatively with serum albumin (P = 0.027 and 0.032, respectively). Both anti-nucleosome and anti-dsDNA levels were significantly lower during renal remission than when renal disease was active (P = 0.002 and 0.003, respectively). However, there was no relationship between anti-α-actinin levels and urine PCR, serum albumin or remission status.
This prospective longitudinal clinical study is the first to compare levels of anti-nucleosome, anti-dsDNA and anti-α-actinin antibodies in the same patients with SLE. Our results support the concept that, in the majority of patients, anti-nucleosome antibodies play a major role in pathogenesis of LN, in contrast to anti-α-actinin antibodies.
Objective: To compare the efficacy and side effects of intermittent pulse cyclophosphamide plus methylprednisolone with continuous oral cyclophosphamide plus prednisolone, followed by azathioprine, in patients with proliferative glomerulonephritis caused by systemic lupus erythematosus (SLE).
Methods: A multicentre randomised controlled trial was conducted between June 1992 and May 1996 involving eight European centres. All patients satisfied the American College of Rheumatology criteria for SLE and had biopsy proven proliferative lupus nephritis. All received corticosteroids in addition to cytotoxic drugs, as defined in the protocol, for two years. The trial was terminated after four years as recruitment was disappointing.
Results: 32 SLE patients with lupus nephritis were recruited: 16 were randomised to intermittent pulse cyclophosphamide and 16 to continuous cyclophosphamide plus azathioprine. Mean duration of follow up was 3.7 years in the continuous group (range 0 to 5.6) and 3.3 years in the pulse group (range 0.25 to 6). Three patients were excluded from the pulse therapy group as they were later found to have pure mesangial glomerulonephritis. Two patients in the continuous therapy group developed end stage renal failure requiring dialysis, but none in the intermittent pulse therapy (p = 0.488; NS). There were similar numbers of side effects and withdrawals from treatment in both groups. There were three deaths: two in the intermittent pulse therapy group and one in the continuous therapy group.
Conclusions: There was no statistically significant difference in efficacy and side effects between the two regimens. Infectious complications occurred commonly, so careful monitoring is required during treatment.
Lupus nephritis is a frequent and serious complication of systemic lupus erythematosus (SLE). Treatment often requires the use of immunosuppression, and may be associated with severe side effects. The ability to predict relapse, relapse severity, and recovery could be used to more effectively implement therapy and reduce toxicity. We postulated that a proteomic analysis of the low-molecular weight urine proteome using serial urine samples obtained before, during, and after SLE nephritis flares would demonstrate potential biomarkers of SLE renal flare. This study was undertaken to test our hypothesis.
Urine from 25 flare cycles of 19 WHO Class III, IV, and V SLE nephritis patients was used. Urine samples included a baseline, and pre-flare, flare, and post-flare specimens. The urines were fractionated to remove proteins larger than 30 kDa, and spotted onto weak cation exchanger (CM10) protein chips for analysis by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS).
SELDI-TOF MS screening showed 176 protein ions between 2-20 kDa of which 27 were found to be differentially-expressed between specific flare intervals. On-chip peptide sequencing by integrated tandem mass spectrometry was used to positively identify selected differentially-expressed protein ions. The identified proteins included the 20 and 25 amino acid isoforms of hepcidin, a fragment of α1-antitrypsin, and an albumin fragment. Hepcidin 20 increased 4 months pre-flare and returned to baseline at renal flare, whereas hepcidin 25 decreased at renal flare and returned to baseline 4 months post-flare.
Using SELDI-TOF urine protein profiling in lupus nephritis, several candidate biomarkers of renal flare were found. To verify these candidates as true biomarkers, further identification and validation are needed in an independent SLE cohort.
lupus nephritis; biomarker; SELDI
Systemic lupus erythematosus (SLE) is a typical autoimmune disease that's characterized by various autoantibodies to nuclear and cytoplasmic antigens. The presence of antinuclear antibodies (ANA) in serum is generally considered a decisive diagnostic sign of SLE. However, a small subset of SLE patients who had the typical clinical features of SLE was reported to show persistently negative ANA tests. Our report describes a 16-yr-old female who presented with the clinical manifestations of SLE such as malar rash, photosensitivity, arthritis, lymphopenia, pericarditis and proteinuria. The serum autoantibodies were all negative and renal biopsy showed that the histopathological changes of immune complex mediated the focal segmental necrotizing glomerulonephritis with crescent formation. She was treated with monthly pulse cyclophosphamide along with corticosteroids. During the 2-yr follow-up period, the proteinuria was markedly decreased and all of the ANA and anti-double stranded DNA antibody tests were negative. This case suggests that ANA may not be required in the pathogenesis of lupus nephritis.
Antinuclear antibody; Lupus nephritis; Systemic lupus erythematosus
Clinicians can diagnose high urine calcium by asking patients to collect urine for 24 h or to provide a random urine specimen. In this study, random urine calcium levels were not as accurate as those from the 24-h collection. Clinicians should only use 24-h collections to diagnose high urine calcium.
Clinicians diagnose hypercalciuria using a 24-h urine calcium (24HUC) or a spot urine-calcium-to-creatinine ratio (SUCCR) specimen. The SUCCR is reportedly interchangeable with the 24HUC. However, studies to date show mixed results when comparing SUCCR and 24HUC values. We systematically compared fasting and postprandial SUCCR measurements to 24HUC measurements using Bland–Altman analysis.
Twenty-one postmenopausal women aged 58± 7 years came to the research ward for three 24-h inpatient stays. At each study visit, research nurses collected fasting morning (n=62) and postprandial (n=62) spot urine specimens along with carefully timed and complete 24-h urine specimens (n=63) from each woman.
Hypercalciuria was present in 13 24HUC samples (21%) using an upper limit of 250 mg/24-h. The fasting SUCCR underestimated the 24HUC (Bland–Altman bias −71 mg/24-h), with a sensitivity and specificity for diagnosing hypercalciuria of 0% and 98%, respectively. The postprandial SUCCR overestimated the 24HUC (Bland–Altman bias +61 mg/24-h), with a sensitivity and specificity of 77% and 61%, respectively. The average of fasting and postprandial SUCCR measurements had a lower Bland–Altman bias of −3 mg/24-h but demonstrated a sensitivity and specificity of only 42% and 78%, respectively.
The SUCCR is not interchangeable with the 24HUC. The fasting SUCCR systematically underestimates, and the postprandial SUCCR systematically overestimates, 24HUC. The average SUCCR demonstrates low sensitivity and specificity for hypercalciuria. Clinicians must use the 24HUC to diagnose hypercalciuria in postmenopausal women.
Calcium; Diagnosis; Hypercalciuria; Nephrolithiasis; Osteoporosis; Urine
Serum levels of C-reactive protein (CRP) seldom reflect disease activity in systemic lupus erythematosus (SLE). We have previously shown that autoantibodies against neo-epitopes of CRP often occur in SLE, but that this does not explain the modest CRP response seen in flares. However, we have repeatedly found that anti-CRP levels parallel lupus disease activity, with highest levels in patients with renal involvement; thus, we aimed to study anti-CRP in a material of well-characterized lupus nephritis patients.
Thirty-eight patients with lupus nephritis were included. Treatment with corticosteroids combined with cyclophosphamide, mycophenolate mofetil or rituximab was started after baseline kidney biopsy. A second biopsy was taken after ≥ 6 months. Serum creatinine, cystatin C, complement, anti-dsDNA, anti-CRP and urinalysis were done on both occasions. Biopsies were evaluated regarding World Health Organisation (WHO) class and indices of activity and chronicity. Renal disease activity was estimated using the British Isles Lupus Assessment Group (BILAG) index.
At baseline, 34/38 patients had renal BILAG-A; 4/38 had BILAG-B. Baseline biopsies showed WHO class III (n = 8), IV (n = 19), III to IV/V (n = 3) or V (n = 8) nephritis. Seventeen out of 38 patients were anti-CRP-positive at baseline, and six at follow-up. Overall, anti-CRP levels had dropped at follow-up (P < 0.0001) and anti-CRP levels correlated with renal BILAG (r = 0.29, P = 0.012). A positive anti-CRP test at baseline was superior to anti-dsDNA and C1q in predicting poor response to therapy as judged by renal BILAG. Baseline anti-CRP levels correlated with renal biopsy activity (r = 0.33, P = 0.045), but not with chronicity index. Anti-CRP levels were positively correlated with anti-dsDNA (fluorescence-enhanced immunoassay: r = 0.63, P = 0.0003; Crithidia luciliae immunofluorescence microscopy test: r = 0.44, P < 0.0001), and inversely with C3 (r = 0.35, P = 0.007) and C4 (r = 0.29, P = 0.02), but not with C1q (r = 0.14, P = 0.24). No associations with urinary components, creatinine, cystatin C or the glomerular filtration rate were found.
In the present study, we demonstrate a statistically significant correlation between anti-CRP levels and histopathological activity in lupus nephritis, whereas a baseline positive anti-CRP test predicted poor response to therapy. Our data also confirm previous findings of associations between anti-CRP and disease activity. This indicates that anti-CRP could be helpful to assess disease activity and response to therapy in SLE nephritis, and highlights the hypothesis of a pathogenetic role for anti-CRP antibodies in lupus nephritis.
Lupus nephritis is one of the most serious manifestations and one of the strongest predictors of a poor outcome in systemic lupus erythematosus (SLE). Recent evidence implicated a potential role of interlukin-17 (IL-17) in the pathogenesis of lupus nephritis. However, the correlation between IL-17 expression level and the severity of lupus nephritis still remains incompletely understood. In this study, we found that serum IL-17 expression level was associated with the severity of lupus nephritis, which was evaluated by histopathology of kidney sections and urine protein. Of note, we showed that enforced expression of IL-17 using adenovirus construct that expresses IL-17 could enhance the severity of lupus nephritis, while blockade of IL-17 using neutralizing antibody resulted in decreased severity of lupus nephritis. Consistently, we observed an impaired induction of lupus nephritis in IL-17-deficient mice. Further, we revealed that IL-17 expression level was associated with immune complex deposition and complement activation in kidney. Of interest, we found that IL-17 was crucial for increasing anti-double-stranded DNA (dsDNA) antibody production in SLE. Our results suggested that IL-17 expression level positively correlated with the severity of lupus nephritis, at least in part, because of its contribution to anti-dsDNA antibody production. These findings provided a novel mechanism for how IL-17 expression level correlated with disease pathogenesis and suggested that management of IL-17 expression level was a potential and promising approach for treatment of lupus nephritis.