Objective: To determine if the 12-hour urine total protein value correlates with the 24-hour value and to evaluate the random protein:creatinine ratio as a predictor of significant proteinuria (> or = 300 mg/24 h) for use in diagnosing preeclampsia.
Study design: The study population included 15 patients with hypertensive disorders of pregnancy. The patients' urine was collected over 24 hours in 2 12-hour aliquots. The urine volume, total protein and creatinine were measured. The patients' initial voids were collected and evaluated for random urine protein and creatinine and calculation of the protein:creatinine ratio. The protein:creatinine ratio and 12-hour results were compared to the 24-hour results using simple regression analysis.
Results: Of the 15 patients, 6 had no proteinuria, 5 had mild proteinuria, and 4 had severe proteinuria (60% with significant proteinuria). The 12-hour protein results correlated with the 24-hour results for patients with mild disease (p = 0.00007, first 12 hours, and p = 0.012, second 12 hours) and severe disease (p = 0.014 and p = 0.007). The results for no disease were mixed: for the first 12 hours there was a poor correlation, but the results for the second 12 hours correlated well. The protein:creatinine ratio had a significant correlation (p = 0.02), using a cutoff of 0.15, returned specificity of 50%, sensitivity of 100%, positive predictive value of 75% and negative predictive value of 100%.
Conclusion: Total protein values for 12- and 24-hour urine samples correlate well for the diagnosis of preeclampsia. A protein:creatinine ratio of < or = 0.15 rules out significant proteinuria. In combination, these 2 tests may allow more rapid diagnosis of preeclampsia.