Comparing the protein of 2-hour and 24-hour urine samples in patients with suspected preeclampsia

  Background : Determining the protein content of a 24-hour urine sample is the gold standard for diagnosis of hypertensive disorders in pregnancy.   Objective: To determine whether the 2-hour urine protein value can be used as a substitute for the 24-hour urine protein value in patients with preeclampsia.   Methods: This was a cross sectional study performed on 60 inpatient women with suspected preeclampsia due to positive urinary test strip with minimum protein content of 1+ and BP≥140/90 at Kosar Teaching Hospital in Qazvin (Iran) during autumn and winter 2008. Urine samples were collected within 24 hours in successive periods: The first 2-hour and the next 22-hours urine, in separate containers. The protein contents of 2-hour and 24-hour urine samples were calculated and the correlation between both groups was determined using Pearson's correlation. The cut off point for 2-hour urine protein was obtained with ROC curve.   Findings: Of 60 patients studied, 42 had proteinuria less then 0.3gr/24h and 18 with proteinuria higher than 0.3gr/24h. No patient with severe proteinuria (>2gr/24h) was detected. There was a significant correlation between the 2-hour and 24-hour urine protein content in patients’ samples. Pearson's correlation coefficient (r) was 0.788 (p=0.000). The cut off point for mild proteinuria was determined at 0.035gr/2h with sensitivity, specificity, positive predictive value, and negative predictive value of 63.3%, 89.5%, 77.8%, and 80.95%, respectively.   Conclusion: Total protein values of 2-hour samples positively correlated with values of 24-hour samples of preeclamptic women and therefore can be substituted for assessing the protein content of 24-hour urine samples as a more convenient, faster, and cheaper method for diagnosis of preeclampsia.