Endocrine Abstracts

Background: Pregnancy is a physiological state characterised by enhanced thyroid hormone production resulting in increased demand for iodine. Iodine deficiency during pregnancy, is therefore, considered to be a risk factor for adequate growth and development in offspring. However our understanding of thyroid hormone homeostasis in iodine deficient environment is limited.

Objectives: 1)To assess the current iodine status in pregnant women from an endemic zone 2) to assess the impact of iodine deficiency on homeostatic adjustments of thyroid hormones, pregnancy outcome and health of pregnant women.

Method: Epidemiological observational survey included pregnant women (18-48 year) from 10 villages of the Bihar State in India (2014-2018) in association with Government Hospital and Government Primary Health Centers. Total 900 healthy pregnant women fulfilling inclusion criteria were enrolled. A questionnaire survey was conducted for demographic socioeconomic and other parameters. Salt samples from relevant households were obtained for the measurement of iodine using State Govt UNICEF kits. Body weight, height and BMI were recorded. Blood and urine samples were procured from subsets of population for the assessment of UIC and thyroid hormones (TSH, FT₄) respectively. UIC was measured spectrophotometrically. TSH & FT4 were measured in DBS using ELISA and Chemiluminiscence methods. IEC approval & informed consent were obtained.

Results: Dietary iodine intake was less than 15ppm in 50% of pregnant women. UIC median values indicated iodine deficiency viz., 73, 82, 84 in 1^st, 2^nd, 3^rd trimester with 88%,96% and 94% subjects iodine deficient, respectively. Evidently dietary iodine intake need not necessarily reflect UIC status of a population. TSH mu/l ranged as 1.3-5.1, 1.47-5.79, 2.32 -6.5 in 1^st, 2^nd, 3^rd tri indicating an increasing trend reflected in the quartile distributions. FT4 pmol/l ranged from 7.02-18.44, 7.19-19, 4.59-16.9 indicating a decline in 3^rd tri. While FT4 values were comparable, TSH consistently was higher than the prescribed international guideline cut-offs. However, no individual showed overt symptoms of hypothyroidism. Pregnancy outcome (still birth, miscarriages) and BMI values were comparable with Indian/world normal figures.

Conclusion: TSH values were above the international standard cut offs and may represent an attempt to restore equilibrium ensuring adequate thyroxine supply in these iodine deficient women. According to population outliers the TSH values were apparently normal (within 2.5-97.5 percentile). Financial assistance from Apeejay Education Society, and, facilities from Swami Rama Himalayan University, Uttarakhand, are gratefully acknowledged. Ms Snehlata Tendi is a recipient of RGNF-UGC Junior Research Fellowship.