Quantitation of proteinuria using protein-creatinine ratio in random urine samples.

Estimation of proteinuria in children is cumbersome when a 24 h urine collection is needed. In the presence of a stable glomerular filtration rate, the ratio of urinary protein and creatinine should reflect the protein excretion. One hundred samples of urine (24 h and random samples) were collected from 50 children with nephrotic syndrome, 25 with nephrotic syndrome in remission and 25 normal children. The 24 h urine total protein and random urine protein-creatinine ratio were assessed on these samples. Linear regression analysis of the results showed excellent correlation between the values (r = 0.81, p less than 0.001). A random urine protein-creatinine ratio of greater than 3.5 correlated with massive proteinuria, while a ratio less than 0.2 was suggestive of physiological values. The sensitivity, specificity, positive and negative predictive values of the protein-creatinine ratio in massive proteinuria were very high. We conclude that the random urine protein-creatinine ratio can be used reliably to assess the degree of proteinuria in children.