Abstract 466: Carotid Atherosclerosis on the Association Between Hypothyroidism and Renal Dysfunction in a Healthy Japanese Population

Aim: This large-scale Japanese population study was done to evaluate the relation between the serum thyroid stimulating hormone (TSH) level and renal function. Methods: Among 1,374 residents who attended a free public physical examination between 2010 and 2011, we evaluated the data of 888 for whom the serum TSH level and estimated glomerular filtration rate (eGFR) were successfully measured. The participants were divided into three groups by TSH level (normal TSH, ≤2.4; high-normal TSH, 2.5-4.4; subclinical hypothyroid, ≥4.5 μIU/L). Multiple linear regression analysis adjusted for cardiovascular risk factors was done to determine the relation between serum TSH level and renal function. Results: The mean ± SD TSH level was 2.0±1.4 μIU/mL. Of the participants, 75.9% (n=674) had a normal TSH level, 17.9% (n=159) were high-normal TSH, and 6.2% (n=55) were subclinical hypothyroid. The mean eGFR significantly decreased with increased TSH level (normal TSH group, 79.3±14.1; high-normal TSH group, 77.4±13.0; subclinical hypothyroid group; 72.3±12.2 mL/min/1.73m2: P for trend <0.01). Multiple linear regression analysis extracted log-transformed TSH level as an independent factor correlated with eGFR in the high-normal TSH group (beta=-0.18, P=0.02). Conclusions: The eGFR level significantly decreased with increased TSH level. Significant correlation between TSH and eGFR levels was found only in high-normal TSH individuals. Even in healthy individuals, increase risk of chronic kidney disease could be started from high-normal TSH level.