ENDOCRINE AND CLINICAL ASSESSMENT OF THYROIDAL FUNCTION IN PREGNANT MOTHERS AND NEONATES FROM IODINE DEFICIENT REGIONS OF PAKISTAN

Abstract

The present study was undertaken to examine the clinical and endocrine parameters of thyroid in a total of 460 pregnant women belonging to non-goitre areas (group 1; n= 156) and endemic areas with no iodine supplementation (group 2; n=154) and iodine supplementation (group 3; n=150), and their respective new-boms. Blood samples were obtained during each trimester and after delivery. Serum triiodothyronine (T3), thyroxine (T4) and thyroid stimulating hormone (TSH) levels were measured by specific enzyme immunoassays. Umbilical cord blood samples were obtained at parturition and analyzed for serum T4 and TSH levels. Women of goitre-endemic areas (group 3) with visible goitre were administered two capsules of iodized oil orally each containing 200 mg of iodine, within 4-6 weeks of pregnancy. The efficacy of iodine supplementation was assessed by observing changes in thyroid hormones, TSH and birth weights of new-borns, and clinically evaluating the regression in the goitre size. There was a significant increase in the T3, T4 and TSH levels, throughout pregnancy in all the three groups. However, there was a significant decrease in the hormone levels after the delivery. In group 2 serum T4 concentrations were low while T3 and TSH levels were high which showed hypothyroidism in the women of endemic areas. Goitre size decreased in most of the subjects who received a single dose of iodized oil. There was an increase in serum concentrations of thyroid hormones, whereas TSH levels decreased. However, the levels could not become comparable to those observed in women of non-goitre areas (group 1). Iodinesupplementation also resulted in raised T4 and low TSH levels in the cord-blood of the neonates. The cord-blood serum TSH levels were high when compared with the values of mothers in all the study groups. During the course of study 2 abortions occurred in the women of group 2 and none in the women of group 1 and 3. There was no stillbirth in the women of group 3 while 1 in group 1 and 3 stillbirths in group 2 women were observed. All the new-borns were normal except one cretin was born in the group 2 women. The present study reveals that the oral administration of a single dose of iodized oil is capable of correcting iodine deficiency both clinically and endocrinologically in mothers and neonates. Iodine supplementation decreases reproductive losses and also has a positive impact on the birth weight of new-borns.