Calcium to creatinine ratio in a spot sample of urine for early prediction of pre-eclampsia

Objectives: Based on the fact that urinary calcium excretion decreases in pre-eclampsia, this study was designed to determine the predictive value of calcium to creatinine ratio in a spot urine sample. Methods: The calcium to creatinine ratio was measured in a spot urine sample of 102 normotensive women at 20–24 weeks’ gestation who attended the prenatal care clinic of the Shiraz University of Medical Sciences. The women were followed-up until delivery and grouped according to pre-eclampsia occurrence. The prevalence of pre-eclampsia was measured and compared with the calcium to creatinine ratio. Results: Ninety-four women remained normotensive during pregnancy and eight developed pre-eclampsia. Mean age, gestational age at the beginning of the study, and gestational age at delivery did not differ significantly between the two groups. Mean urinary calcium concentration (15.9±8.5 mg/dl in normotensive vs. 10.2±7.5 mg/dl in pre-eclamptic women), and mean birth weight (3192±336.3 g vs. 2712±468.9 g) were significantly lower in pre-eclamptic patients (P=0.03 and 0.005, respectively). Mean calcium to creatinine ratio was also significantly lower in the pre-eclamptic group (P<0.03). Conclusions: Single urine calcium to creatinine ratio may be an effective method for screening women at greatest risk for pre-eclampsia.