Thyroid Dysfunction in Children Exposed to Iodinated Contrast Media

Context: Iodinated contrast media (ICM) is routinely used in imaging studies and contains several 100-fold the recommended daily allowance of iodine. Objective: To determine whether children exposed to ICM have a higher risk of iodine-induced thyroid dysfunction. Design: This was a single-institution case-control study, examining patients with incident thyroid dysfunction aged less than 18 years from 2001 to 2015. Cases were matched 1:1 to euthyroid controls by age, sex, and race. Setting: This was a single-institution case-control study occurring at tertiary care center. Participants: Cases were defined as those with thyroid dysfunction (by International Classification of Diseases, Ninth Revision diagnosis codes and/or 2 consecutive abnormal serum TSH values <6 mo apart). We analyzed 870 cases matched to 870 controls (64% female, 51% White). Main Outcomes Measures: Using conditional logistic regression, the association between ICM exposure and the primary outcome, thyroid dysfunction, occurring within 2 years of exposure was assessed. Results: Sixty-nine patients received ICM, including 53 (6%) among cases and 16 (2%) among controls. The risk of incident hypothyroidism was significantly higher after ICM exposure (odds ratio 2.60; 95% confidence interval, 1.43-4.72; P < .01). The median interval between exposureand onset of hypothyroidism was 10.8 months (interquartile range, 6.6-17.9). In hypothyroid cases, the median serum TSH concentration was 6.5 mIU/L (interquartile range, 5.8-9.6). Conclusions: ICM exposure increases the risk of incident hypothyroidism in pediatric patients. Children receiving ICM should be monitored for iodine-induced thyroid dysfunction, particularly during the first year after exposure.