Iodinated contrast media exposure and incident hyperthyroidism and hypothyroidism in a community-based cohort

Abstract

Recent data suggest iodinated contrast media (ICM) exposure is associated with increased risk of incident hyperthyroidism among patients receiving care from two tertiary care medical centers. We sought to confirm and generalize these findings by conducting a case-control study among a broadly-representative community-based cohort of patients receiving care within Harvard Vanguard Medical Associates from 1996 to 2012. Incident hyperthyroid and hypothyroid cases were defined by change in thyrotropin (TSH) from normal (at baseline), to low or high (at follow-up), respectively. In parallel analyses, hyper- and hypothyroid cases were matched to euthyroid controls using incidence density sampling, and ICM exposure was ascertained using claims data. Secondary analyses examined associations with incident overt hyperthyroidism and overt hypothyroidism (follow-up TSH≤0.1 mIU/L and TSH>10 mIU/L, respectively). We observed that ICM exposure was associated with increased risk of incident hyperthyroidism [odds ratio, 1.61 (95% CI) 1.27-2.04], incident overt hyperthyroidism [odds ratio, 1.62 (95% CI) 1.08-2.43], and incident overt hypothyroidism [odds ratio 2.01 (95% CI) 1.25-3.23]. These data confirm that ICM exposure is associated with increased risk of incident thyroid functional disease in a community-based cohort of patients in an iodine-sufficient region.