Iodinated Contrast Media Increased the Risk of Thyroid Dysfunction: A 6-Year Retrospective Cohort Study

Context: The risks of thyroid dysfunction after iodinated contrast media (ICM) exposure are largely unknown, especially in Asian populations. Objective: The objective was to determine whether ICM exposure in patients with normal thyroid would increase the risk of thyroid dysfunction, including hyperthyroidism or hypothyroidism. Design: This was a retrospective cohort study including a random selection of 1 million people in 2005. Setting: General population of Taiwan was studied. Patients: Patients with ICM exposure were identified as cases, whereas patients without any ICM exposure were selected as controls. Intervention: Interventions included ICM exposure or nonexposure in normal thyroid function patients. Main Outcome: The primary endpoint was the composite risk of thyroid dysfunction associated with ICM exposure. Results: A total of 19 642 cases and 78 568 matched controls were recruited in this study. The mean ages of ICM exposure and nonexposure were 53.9 and 53.6 years, respectively, and mean follow-up durations were 4.1 and 5.6 years, respectively. After adjustment, patients with ICM exposure had a significantly higher risk of thyroid dysfunction (hazard ratio, 1.46; 95% confidence interval [CI], 1.29–1.66). In the subgroup analysis, the adjusted hazard ratios of hyperthyroidism and hypothyroidism compared with controls were 1.22 (95% CI, 1.04–1.44) and 2.00 (95% CI, 1.65–2.44), respectively. Conclusions: ICM exposure was associated with higher risk of thyroid dysfunction, including hyperthyroidism and hypothyroidism.