Fig. 2

Hazard ratios (HR) of abnormal thyrotropin levels according to baseline thyrotropin levels. Subnormal thyrotropin was defined as thyrotropin < 0.37 mIU/L and supranormal thyrotropin was defined as thyrotropin ≥ 4.88 mIU/L. First column, thyrotropin level at baseline (mIU/L); second column, median of follow-up thyrotropin level (mIU/L); third column, number of participants who developed abnormal thyrotropin in the follow-up; fourth column, HRs of developing abnormal thyrotropin compared to the reference group (thyrotropin 1.01–2.00 mIU/L). Cox proportional hazard regression model was adjusted for age, body mass index, parity, education level, alcohol consumption, passive smoking, diabetes, hypertension, and environmental iodine nutrition status. Abbreviations: TSH, thyrotropin; IQR, interquartile range; HR, hazard ratio; CI, confidence interval