Comparative Analysis of Serum Calcium Level and Thyroid Profile in Pregnant Normotensive and Preeclamptic Women: A Case-control Study

Introduction: Preeclampsia, a transient but potentially dangerous, multisystem disorder is one of the most common complications of pregnancy and is a principal cause of maternal and fetal morbidity and mortality. Calcium deficiency and hypothyroidism have been found to be associated with pregnancy-induced hypertension and preeclampsia. Aim: To estimate the serum calcium level, thyroid profile, their inter-correlation and odds with occurrence of preeclampsia. Calcium and serum Thyroid Stimulating Hormone (TSH) levels were further correlated to Body Mass Index (BMI) of participants and to the birth weight of their newborns to investigate their effects or outcome. Materials and Methods: This cross sectional, case-control study was conducted for a period of one year (July 2018 to June 2019). A total of 170 pregnant women: 80 in preeclampsia group (case group); 90 in normotensive group (control group) were enrolled in the study. All the study subjects were in third trimester and were between 18-45 years of age. Total serum calcium levels and thyroid profile (fT3, fT4 and TSH) of all the study participants were estimated using fully automatic analyser. Proteinuria was measured by urine dipsticks. Results: Mean total serum calcium levels in cases were lower (8.2 +/- 0.8) as compared to controls (8.7 +/- 0.5), p<0.05 whereas, mean serum TSH levels in cases were found to be higher (5.07 +/- 3.34) as compared to controls (3.3 +/- 1.75), p<0.05. Odds Ratio (OR) for total serum calcium level <8.2 mg/dL was 10.8 (95% CI=7.437-7.806 p<0.05 and for serum TSH level >5.7 mu IU/mL was 4.98, (95% CI=6.726-9.831; p<0.05. A combination of these two parameters together was observed in 18.75% of cases as opposed to none in controls. Birth weight of newborns of preeclamptic mothers was found to be positively correlated with total serum calcium level while a negative correlation was observed with serum TSH level. Conclusion: Findings from the present study suggest that serum calcium level was observed as a better indicator and predisposing risk factor for preeclamptic occurrence than serum TSH levels. Screening of thyroid profile and serum calcium levels and analysis of their combined status during pregnancy can help in minimising the risk of preeclamptic occurrence and associated adverse pregnancy outcomes.