A random protein–creatinine ratio accurately predicts baseline proteinuria in early pregnancy

Abstract

Objective: Data surrounding the use of a random urine protein:creatinine ratio (PCR) in the diagnosis of preeclampsia is conflicting. We sought to determine whether PCR in early pregnancy can replace the 24-hour urine collection as the primary screening test in patients at risk for baseline proteinuria.

Methods: Women requiring a baseline evaluation for proteinuria supplied a urine sample the morning after their 24-hour collection. The PCR was analyzed as a predictor of significant proteinuria (≥150 mg). A regression equation to estimate the 24-hour protein value from the PCR was then developed.

Results: Sixty of 135 subjects enrolled completed the study. The median 24-hour urine protein and PCR were 90 mg (IQR: 50–145) and 0.063 (IQR: 0.039–0.083), respectively. Fifteen patients (25%) had significant proteinuria. PCR was strongly correlated with the 24-hour protein value (r = 0.99, p < 0.001) and highly predictive of significant proteinuria (AUC = 0.86). A PCR cut-point of 0.079 yielded a sensitivity of 93.3% and a specificity of 57.8%. The resulting regression equation [total protein = 46.5 + 904.2*PCR] accurately estimates the actual 24-hour protein (95% CI: ±88 mg).

Conclusion: A random urine PCR accurately estimates the 24-hour protein excretion in the first half of pregnancy and can be used as the primary screening test for baseline proteinuria in at-risk patients.

• 24-hour urine
• baseline proteinuria
• PCR
• preeclampsia