1568 PREDICTION OF PROTEINURIA BY RANDOM AND 24 HOUR URINE PROTEIN CREATININE RATIOS (U P/Cr) IN NEPHROTIC CHILDREN

Abstract

The feasibility of using the U P/Cr to predict dally protein excretion in nephrotic patients was tested in 125, 24 hour urine collections from 47 children with nephrotic syndrome (aged 19 mos - 16 years). Six patients were steroid non-responsive and had focal segmental sclerosis by biopsy; all others were considered to have minimal change disease either by biopsy or Prednisone responsiveness. Urine protein was measured by the Coomassle blue binding technique (Bio-Rad Lab) and creatinine by the spectre-photometric Pierce Test Kit. Total protein excretion (TP) ranged from 2 mg to 32 g/m2/day. U P/Cr ranged from .002 to 33 in 24 hour urine samples. The correlation between daily protein excretion and U P/Cr was highly significant (n = 125, r = 0.57, p < 0.001). However, the scattergram of all data suggested non-linearity when proteinuria was minimal (< 100 mg/m2/d) or excessive (> 1 g/m2/d). Logarithmic conversion improved the correlation of data at both extremes of TP:Logarithmic conversion of all data enabled accurate prediction of TP from U P/Cr [n = 125, r = .97, Log TP = 0.9 (Log U P/Cr) -0.5], Random U P/Cr from 9 specimens collected on the day following a 24 hour urine were also predictive of TP (r = 0.96, p < .001). These data support the concept that U P/Cr can accurately predict proteinuria although non-linearity outside moderate ranges requires logarithmic conversion.