quantification of proteinuria with urinary protein to osmolality ratios in children

background: the ratio of urine protein to urine osmolality has recently been suggested as an accurate method to determine proteinuria.   objective: we studied the correlation of urine protein to urine osmolality ratio with 24-hr urinary protein excretion.   methods: 150 children aged 0.11–17 years admitted to the department of pediatric nephrology were included in this study. early morning urine samples and 24-hr urine specimens were collected and analyzed for protein, creatinine, and osmolality. the patients with chronic renal failure were not excluded. two groups were established: children with no proteinuria (group 1) and those with proteinuria (group 2).   results: the optimal cutoff value of abnormal proteinuria and nephrotic range proteinuria was determined to be a protein–osmolality ratio (up/uosm) 0.27 and 1.59 mg/l/mosm respectively. the correlation of 24-hr urinary protein excretion with both urinary protein/creatinine ratio (up/ucr) and up/uosm was highly significant (p<0.001). according to the receiver operator characteristic (roc) curves analysis, we found no differences between up/uosm and up/ucr ratios in detecting either abnormal proteinuria or nephrotic syndrome.   conclusion: urine protein to urine osmolality ratio seems to be a simple and a valuable test for the assessment of the degree of proteinuria in children.