Maternal thyroid hormonal status in preelampsia and Eclampsia at Kenyatta National Hospital - a case control Study

Abstract

Preeclampsia and eclampsia are important causes of maternal and perinatal morbidity and mortality in .developing countries. Although pregnancy is usually associated with mild hyperthyroxinemia, preeclamptic women are reported to have a high incidence of hypothyroidism that might correlate with the severity of preeclampsia. The mechanism of hypothyroidism in preeclamptic women has not been identified but the changes in thyroid function during pregnancy are accounted for by high circulating estrogens (leading to increased thyroid binding globulin). There are controversies about the mechanism and clinical significance of thyroid hormones in preeclampsia, which are attributed to decreased plasma protein concentrations and high levels of endothelin, a potent vasoconstrictor produced by vascular endothelium after vascular injury. The rationale for this study was to describe the correlation, if any, between thyroid hormone and preeclampsia among Kenyan women. Aim: The study evaluated thyroid hormonal status in patients with preeclampsia and eclampsia; and matched normotensive non-proteinuric pregnant mothers at Kenyatta National Hospital. Methods: This was a matched case control study conducted at KNH between February and April 2010, both months inclusive. Seventy (70) subjects, comprising of thirty-five (35) preeclamptics and eclamptics as subjects and a similar number of age- and- gestation matched healthy normotensive pregnant mothers as controls were studied. Demographic and medical data from the study subjects were obtained. Blood was drawn for estimation of serum thyroid stimulating hormone (TSH), serum free thyroxine (FT4) and serum free tri-iodothyronine (FT3) using Enzyme Immunoassay Statistical analysis: The demographic data and hormone levels were analyzed using students t- test and chi-square test. To examine the association between TSH and preeclampsia odds ratio along with 95% confidence interval was estimated for TSH levels. Results: Mean TSH was significantly higher in preeclamptic group when compared to controls (p=O.047). Mean value of serum FT4 was significantly higher in controls compared to subjects (p=O.045). However mean values of serum FT3 were similar between the two groups (p=O.61S). All the values were within the manufacturers reference ranges except in three preeclamptic women who had levels ofTSH > 5mIU/ml which is the upper limit of the normal. However, this was not statistically significant (p=O.05726).