A Comparison of 4- and 24-Hour Urine Samples for the Diagnosis of Proteinuria in Pregnancy

BACKGROUND Preeclampsia is a serious complication of pregnancy, and it is vital to diagnosis the condition as early as possible. Proteinuria is an important symptom of preeclampsia, and repeated urine analysis to screen for the condition is part of the standard antenatal care. The purpose of this study was to determine the correlation between 4- and 24-hour urine total protein values to examine whether the 4-hour urine samples could be used for the diagnosis of proteinuria in hypertensive disorders of pregnancy. METHODS A cross-sectional study was performed on 110 pregnant (after gestational week 20 of pregnancy) patients who were hypertensive (blood pressure ≥140/90 mmHg) and had proteinuria as defined by positive urinary protein of at least 1+ in dipstick. Patients' urine samples were collected over 24 hours; the first 4 hours were collected separately from the next 20-hours. Patients, who did not collect the 24-hour urine, were excluded from the study. One hundred patients met the criteria, and were included in the study. The urine volume, total protein and creatinine levels of 4- and 24-hours samples were measured. The correlation between 4-hour and 24-hour samples was examined using Pearson correlation test. RESULTS Of the 100 patients, 42 had no proteinuria, 44 had mild proteinuria, and 14 had severe proteinuria. The urine protein values of 4-hour samples correlated with those of the 24-hours samples for patients with mild and severe forms of the disease (P<0.001, r=0.86). CONCLUSION This study showed there was a correlation between 4-hour and 24-hour urine proteins. The finding indicates that a random 4-hour sample might be used for the initial assessment of proteinuria.