Background: The physiological changes in the thyroid gland during pregnancy are well understood but only a few reports provide information about thyroid function in complicated pregnancies.
Aims: The present study evaluates thyroid hormonal levels in cases of preeclampsia in the third trimester of pregnancy.
Settings & design: A case-control study was conducted in the antenatal clinic of a public hospital of Delhi.
Method & materials: Thyroid hormones, namely triiodothyronine (Free T3), thyroxine (Free T4) and thyroid stimulating hormone (TSH) were evaluated at the time of diagnosis of preeclampsia in 82 pregnant women and equal number of matched controls.
Statistical analysis: The demographic data and hormone levels were analyzed using students' t test, Mann-Whitney test and chi-square test. Pearson two-tailed analysis was used for correlation.
Results: Mean TSH levels were significantly higher in preeclamptic group as compared to controls (p< 0.001). However, mean values of thyroid hormones were in the normal range. Approximately 40% preeclamptic women had TSH titres > 5 mIU/ml in the study group as compared to 12.2% in the controls. Approximately 76.7% of 43 pregnant women with abnormal TSH titres and 40% of 121 pregnant women with normal TSH titres belonged to the study group (p< 0.001). The odd ratio corresponding to TSH titres > 5 mIU/ml in preeclamptic women was 4.85 (95% CI 2.19-10.74).
Conclusions: Mean serum TSH levels were significantly increased without concomitant changes in free T3 and T4, in preeclampsia compared to normal pregnancy. Abnormal TSH titres might be associated with a risk for occurrence of preeclampsia.