Nitric oxide in preeclampsia and its association with thyroid hormone levels - A case control study

Abstract

Introduction: Preeclampsia is a common disease of vascular dysfunction in pregnancy. Previous studies have suggested that nitric oxide, a vasodilator decreases in preeclampsia. This could lead to a decrease in thyroid capillary flow as suggested by few studies, thereby causing a decrease in thyroid hormones. Present study aims to investigate nitric oxide in preeclampsia and also seeks to find any correlation between nitric oxide and thyroid profile in preeclampsia. Materials and Methods: In this Case-Control study, 40 preeclampsia subjects as cases and 40 pregnant women as controls at 30-38 weeks of gestation were involved. 5 ml of venous blood was collected to assay serum nitric oxide using chemical method (Griess assay) and thyroid profile (T3, T4, TSH, FT3 and FT4) using ELISA. Analysis and Results: Mean, median, standard deviation for quantitative variables was compared by student t test. Percentage values were compared using Chisquare test. ANOVA tests and Post Hoc analysis was done. Nitric Oxide was significantly decreased in preeclampsia (20.5±3.03 µmol/L) than in normal pregnant (26.25±5.09 µmol/L). It was significantly decreased even in mild preeclampsia (p<0.001). There was a decrease in thyroid hormones and increase in TSH in preeclampsia. There was a correlation between decreased nitric oxide levels and decreased T3 and FT4 levels, but not with the remaining thyroid hormones. Conclusion: Preeclampsia is associated with a significant decrease in serum nitric oxide and thyroid hormone levels. In this study, we found correlation between decreased thyroid hormones (T3 and fT4) and nitric oxide levels, which was not significant. However preeclamptic women should be screened for hypothyroidism both during pregnancy and in post-natal period.