The accuracy of the calcium-creatinine ratio in a spot urine sample for predicting preeclampsia

Introduction
Preeclampsia (PE) is a major cause of foetal and maternal morbidity. Currently, there is no reliable diagnostic test to predict PE. To evaluate the accuracy of the calcium-creatinine ratio (CCR) in a spot urine sample for the prediction of PE.

Material and methods
Two hundred and forty-six pregnant women, attending the ante-natal clinic after 20 weeks` gestation were included in this study. After exclusion of pre-existing chronic renal disease affecting calcium and/or creatinine excretion, spot urine samples were taken from participants to detect the CCR. Participants were followed up until delivery; the women who developed PE were included in the PE group and compared with normotensive controls to evaluate the accuracy of CCR in a spot urine sample for the prediction of PE.

Results
The gestational age at delivery and parity were significantly lower in the studied PE group compared to normotensive controls (36.1 ±4.3 weeks and 1.7 ±2.6 vs. 39.1 ±3.1 and 3.4 ±1.9; respectively), (p = 0.0002 and 0.0003; respectively). The body mass index (BMI) was significantly higher in the studied PE group compared to normotensive controls (29.3 ±4.1 vs. 24.6 ±3.3 kg/m2; respectively), (p = 0.01). The calcium-creatinine ratio ≤ 0.04 had 79.3% sensitivity, 96.3% specificity, 91.5% positive predictive value (PPV), 90.3% negative predictive value (NPV), and 90.7% overall accuracy in prediction of PE.

Conclusions
The calcium-creatinine ratio ≤ 0.04 had 79.3% sensitivity, 96.3% specificity, 91.5% PPV, 90.3% NPV, and 90.7% overall accuracy in predicting PE. This study suggests the use of CCR in spot urine sample for screening and early detection of PE.