Comparison between 24‐h proteinuria, urinary protein/creatinine ratio and dipstick test in patients with nephropathy: Patterns of proteinuria in dipstick‐negative patients

Three main tests are commonly employed for the measurement of proteinuria: the dipstick test, the urinary protein/creatinine ratio (P/C) and the 24-h urine collection. The aim of this study was to evaluate the correlation between these methods, comparing linear regression and ROC curve data.A total of 297 consecutive outpatients with different renal diseases were included in the study. Twenty-four-hour proteinuria was considered the reference test.A high degree of correlation was observed between all the tests (p0.0001), the highest regression coefficient being between 24-h proteinuria and P/C (R=0.82), and the lowest between P/C and the dipstick test (R=0.72). The dipstick test failed to detect pathological proteinuria in 94 patients (31.6%). Therefore, in these subjects, the patterns of proteinuria were assessed by immunofixation and sodium dodecyl sulphate (SDS) electrophoresis.Our data strongly support the use of urinary P/C for the detection of proteinuria, at least in nephrology units, where the prevalence of proteinuria is likely to be high.