Prevalence of thyroid dysfunction in infants and young children exposed to iodine-based contrast media: a tertiary care center experience.

PURPOSE: Iodine-based contrast media (ICM) can disrupt thyroid function in young children due to immature thyroid autoregulation. The U.S. FDA has recently recommended monitoring thyroid function in children <3 years following ICM exposure. However, the necessity of routine monitoring remains debated due to limited data. This study aimed to determine the prevalence and risk factors for thyroid dysfunction following ICM exposure in children <3 years. METHODS: An ambidirectional cohort study was conducted in children <3 years who underwent ICM-enhanced imaging. Exclusion criteria included pre-existing thyroid disease, non-thyroidal illness, or abnormal baseline thyroid function tests (TFTs). TFTs were assessed at baseline and 2-3 weeks post-exposure. Prevalence and factors associated with ICM-induced thyroid dysfunction were analysed. RESULTS: Of 80 participants, the mean age at exposure was 198.5 days (range: 2-881 days). Eleven children (13.8%) developed thyroid dysfunction: three required levothyroxine, five had transient hyperthyrotropinemia, two were lost to follow-up, and one initially had transient hyperthyrotropinemia but was later diagnosed with central hypothyroidism. Among those treated, one infant with Down syndrome developed overt hypothyroidism (TSH 152 µIU/L, FT4 0.41 ng/dL), while two others had persistently elevated TSH. ICM-induced thyroid dysfunction was associated with age <6 months (adjusted OR 11.32 [95% CI: 1.34-95.97], P=0.026), and multiple anomalies/syndromic diagnosis showed a trend toward increased risk (adjusted OR 4.98 [95% CI: 0.97-25.63], P=0.055). CONCLUSIONS: Thyroid dysfunction occurred in 13.8% of children <3 years after ICM exposure, with some requiring hormonal therapy. Targeted thyroid monitoring is warranted, especially infants <6 months.