Comparison of 12-hour urine protein and protein:creatinine ratio with 24-hour urine protein for the diagnosis of preeclampsia.

OBJECTIVE: The purpose of this study was to evaluate the performance of the 12-hour urine protein >165 mg and protein:creatinine ratio >0.15 for the prediction of 24-hour urine protein of ≥300 mg in patients with suspected preeclampsia.

STUDY DESIGN: We performed a prospective observational study of 90 women who had been admitted with suspected preeclampsia. Protein:creatinine ratio and 12- and 24-hour urine specimens were collected for each patient. Test characteristics for the identification of 24-hour urine protein ≥300 mg were calculated.

RESULTS: A 12-hour urine protein >165 mg and protein:creatinine ratio of >0.15 correlated significantly with 24-hour urine protein ≥300 mg (r = 0.99; P < .001; and r = 0.54; P < .001, respectively). A 12-hour urine protein >165 mg performed better than protein:creatinine ratio as a predictor of a 24-hour urine protein ≥300 mg (sensitivity, 96% and 89%; specificity, 100% and 49%; positive predictive value, 100% and 32%; negative predictive value, 98% and 91%, respectively).

CONCLUSION: The high correlation of a 12-hour urine protein >165 mg with a 24-hour urine protein ≥300 mg (with the benefit of a shorter evaluation time) and the high negative predictive value of protein:creatinine ratio suggest that the use of both these tests have a role in the evaluation and treatment of women with suspected preeclampsia.