Two-hour urine collection for evaluating renal function correlates with 24-hour urine collection in pregnant patients.

Objective: We sought to determine if 2-h urine collection for the assessment of urine protein excretion and creatinine clearance correlates with 24-h urine collection in pregnant patients with renal disease.

Methods: We enrolled patients of gestational ages ranging from 8-41 weeks, admitted as inpatients and having undergone evaluation for renal function (n = 59). We obtained the following samples: 1) 2-h urine, and 2) 24-h urine. We measured serum creatinine concentration, urinary protein, creatinine concentration, and creatinine clearance. The data was analyzed using descriptive analysis, two-way ANOVA, univariate linear regression analysis, and Bland-Altman plot comparing the efficacy of 2-h urine results with 24-h urine results.

Results: We analyzed the data on 51 patients. Total proteinuria calculated by protein/creatinine (P:C) ratio in the 2-h group correlated with the total protein measured in the 24-h group (1,840.8 +/- 786 and 1,944 +/- 1,060 mg [mean +/- SE], respectively, r2 = 0.95, P < 0.0001). Creatinine clearance correlated in the 2- and 24-h groups (111 +/- 42 and 122.5 +/- 50 ml/min, respectively; r2 = 0.73, P < 0.001).

Conclusion: Two-hour urine sampling offers the same clinical information as 24-h urine collection for the evaluation of renal function. Use of 2-h urine collection reduces the time of evaluation and diagnosis, whereby increasing patient compliance and reducing errors in performance of the tests.