Quantification of proteinuria with urinary protein to osmolality ratios in children with and without renal insufficiency

Abstract

BACKGROUNDSpot urine is recommended as an accurate method to determine proteinuria in children and adults. However, urinary excretion of creatinine may vary in newborns and spot urine may be influenced by the hydration-dehydration condition of patients. The study was done to assess the validity of the urine protein to osmolality ratio versus the urine protein to creatinine ratio in health and disease conditions.METHODSWe studied the correlation of the urine protein-osmolality ratio (Uprot/Uosm) and the urine protein to creatinine ratio (Up/Ucr) and compared results with the 24-hour urinary protein excretion. Three groups were compared: children with normal renal function and without proteinuria (group 1, n=53), children with normal renal function and with proteinuria (group 2, n=52) and patients with renal insufficiency (group 3, n=45). Early morning urine samples and 24-hour urine specimens were collected for protein, creatinine, and osmolality.RESULTSThe optimal cutoff value of the Uprot/Uosm ratio was determined to be 0.33 mg/L/mosm/kgH2O for abnormal proteinuria and 1.75 mg/L/mosm/kgH2O for nephrotic range proteinuria. In comparing ROC curves, we found no differences between the Uprot/Uosm and Up/Ucr ratios in detecting abnormal proteinuria or nephrotic syndrome in children with normal or decreased renal function (P>0.05).CONCLUSIONBoth the Uprot/Uosm and Up/Ucr ratios from random urine specimens are good predictors of 24-hour urinary total protein excretion in children with and without renal insufficiency.

Comparison of Spot Urine Protein/Creatinine Ratio, Spot Urine Protein/Osmolality Ratio with Measured 24-Hour Urine Protein in HIV Subjects in Nigeria

“…There was no difference between SUPCR and SUPOR in predicting 24 HUP at this level. This is similar to the findings reported by two studies with slightly higher AUROC [19,20]. This is in keeping with some earlier studies [19,20].…”

“…This is similar to the findings reported by two studies with slightly higher AUROC [19,20]. This is in keeping with some earlier studies [19,20]. However SUPCR was found to be better than SUPOR when compared with 24 HUP in another study [21].…”

Assessment of the validity of protein - osmolality ratio in a randomly collected urine specimen, in the estimation of proteinuria in children

“…The cut-off value of protein-osmolality ratio to diagnose abnormal proteinuria was 0.38 mg/L: mOsmoles/kgH 2 O. This figure is close to the values reported by Kim et al and Hooman et al who used the turbidimetric method for measuring urinary protein (0.23 and 0.27 mg/L: mOsmoles/kgH 2 O respectively) 7,8 . Cut-off value to detect abnormal urinary protein excretion obtained in our study is higher than the value obtained by Morgenstern et al (0.15 mg/L: mOsmoles/kgH 2 O) where urine protein was measured by the pyrogallol red method, as in our study 4 .…”

“…In the study by Morgenstern et al the results in the paediatric population differed from the adult population, in that both protein-osmolality and protein-creatinine ratios were equally predictive of abnormal proteinuria in adults 4 . Hooman et al reported that according to ROC curves there is no difference between these two ratios in detecting either abnormal proteinuria or nephrotic proteinuria 7 .…”

“…Several studies have reported urine protein-osmolality ratio in a random urine sample, as a valuable predictor for the assessment of quantitative proteinuria in children as well as in adults 5--10 . Normative data for urine protein-creatinine and urine protein-osmolality ratio have been published for adults and paediatric population 4,7,10 . Few studies on direct statistical comparisons between the two ratios have been published 4 .…”