Reduced sensitivity to thyroid hormone is associated with diabetes and hypertension.

Abstract

BACKGROUND\nRecently, reduced sensitivity to thyroid hormone as a more common finding in the general population and its possible association with metabolic parameters has been the focus of attention. We evaluated the cross-sectional association of thyroid hormone sensitivity with diabetes, metabolic syndrome (MetS), and its components.\n\n\nMETHODS\nThe study included a Tehranian representative sample of 5124 subjects aged ≥20 years participating in the Tehran Thyroid Study (2008-2011). Body weight, waist circumference and blood pressure were measured, and serum concentrations of lipids and lipoproteins, fasting blood glucose (FBG), insulin, free T4 (fT4) and TSH were assayed. Thyroid hormone resistance was calculated by thyroid feedback quantile-based index (TFQI) and Iranian-referenced parametric TFQI (PTFQI) and compared with two other indices of TT4RI and TSHI.\n\n\nRESULTS\nTFQI was significantly associated with high BP metabolic syndrome criterion (OR=1.14, 95% CI: 1.06, 1.23) and DM (OR=1.16, 95% CI: 1.04, 1. 30, p=0.009) in euthyroid subjects after adjusting for age, sex, smoking, physical activity, BMI, and HOMA-IR. TFQI was not associated with new-onset diabetes contrary to known diabetes in subgroup analysis. The results were similar for PTFQI. TSHI (OR=1.22, 95% CI: 1.08, 1.38, P=0.001) and TT4RI (OR=1.08, 95% CI: 1.01, 1.16, P<0.001) were associated only with high BP in euthyroid subjects.\n\n\nCONCLUSION\nThe new TFQI index seems to be the indicator of reduced sensitivity to thyroid hormone most suitable to associate its population variations with diabetes and hypertension in euthyroid subjects; however, interpretation for diabetes should be concerned with cautions, necessitating future studies.