The Relationship Between Iodine Status and Thyroid Stimulating Hormone (TSH) and Free T4 (FT4) in Women of Childbearing Age in Wonogiri Regency

Abstract

The urinary iodine concentration (UIC) is the most common indicator for assessing the population's iodine status. Urinary iodine does not provide information about thyroid function directly. However, iodine status is an important determinant of thyroid disorders in women of childbearing age. This study aimed to know the relationship between iodine status and thyroid function using indicators of stimulating thyroid hormone (TSH) and free T4 (FT4) levels in women of childbearing age in Wonogiri Regency. A community-based cross-sectional study was conducted in Kismantoro and Slogohimo sub-districts, Wonogiri Regency. A simple random sampling procedure was used to select the study participants. A total of 170 women aged 15-49 years were assessed for UIC, and serum TSH and FT4 levels. The ammonium persulfate digestion method measured urinary iodine concentration (UIC). Serum TSH and FT4 levels by enzyme-linked immunosorbent assay (ELISA). Variables with nominal scales were presented as frequencies and percentages. Correlation analysis was done to find an association between variables. A p-value < 0.05 was considered significant with a CI of 95%. The median UIC was 247.45 μg/L (232.5-1004), indicative of more than adequate. The mean TSH (2.04 ± 2.24 μIU/ml) and FT4 (1.31 ± 0.30 ng/dl) concentrations were within normal reference ranges. The UIC no significantly correlated with serum TSH p = 0.664 (p > 0.05), FT4 p = 0.845 (p > 0.05) levels and thyroid functions p = 1.000 (p > 0.05). Finally, iodine intakes assessed by UIC in our study of women of childbearing age were regarded as sufficient in Wonogiri Regency, and no correlation was found between UIC and thyroid function test.