Analysis of Proteinuria Estimation Methods in Hypertensive Disorders of Pregnancy

The gold-standard 24-h urine collection method for protein estimation is inconvenient and is associated with a delay in laboratory analysis. This study was undertaken to compare sulphosalicylic acid test, urine dipstick test, urine protein-to-creatinine ratio with 24-h urine protein estimation in pre-eclampsia cases.

This is a comparative study and consists of a single group of 764 subjects. This study was conducted in the Department of Obstetrics and Gynaecology in collaboration with the Department of Biochemistry, JIPMER, Pondicherry, India, from February 2011 to January 2014. The subjects included were 764 pre-eclampsia women. A first voided morning sample was obtained for sulphosalicylic acid test, dipstick test, urine protein and creatinine estimation and urine culture, and subsequent urine samples were collected for the 24-h urine protein estimation.

For significant proteinuria, sulphosalicylic acid test with 1 + proteinuria has sensitivity, specificity, PPV and NPV of 59, 48, 39, 67, whereas with 2 + has sensitivity, specificity,PPV and NPV of 44, 88, 75 and 67%, respectively, dipstick test with 1 + proteinuria has sensitivity, specificity, PPV and NPV of 71, 52, 54 and 70%, whereas with 2 + has sensitivity, specificity,PPV and NPV of 49, 87, 75 and 69%, respectively. The spot urine protein-to-creatinine ratio and 24-h urine protein were significantly correlated (r = 0.98; p < 0.0001). The cut-off value for the protein-to-creatinine ratio as an indicator of protein excretion ≥ 300 mg/day was 0.285. The sensitivity, specificity PPV and NPV were 100, 99, 100 and 99%, respectively.

The spot urine protein-to-creatinine ratio is a better method for estimation of proteinuria in pre-eclampsia.