Incidence of Thyroid Dysfunction in Children < 3 Years of Age After Exposure to Iodine-Containing Contrast Agents During Cardiac Catheterization

Background: In March 2022, the U.S. Food and Drug Administration (FDA) issued a drug safety communication recommending evaluation for thyroid dysfunction in all patients under three years of age, three weeks after exposure to iodinated contrast media (ICM). The purpose of this study was to describe the incidence of thyroid dysfunction following ICM exposure during cardiac catheterizations in children < 3 years of age. Study Design: Thyroid function tests (TFT), including serum thyroid-stimulating hormone (TSH) and free thyroxine (free T4) levels, were measured in children < 3 years of age exposed to ICM during cardiac catheterization, both pre-procedure and 3-weeks post-procedure, between May 2022 and April 2023. Clinical hypothyroidism was defined as a low free T4 level and high TSH level compared to reference standards. Results: Eighty patients were included in the analysis, undergoing 99 cardiac catheterization procedures with exposure to ICM. The median age and weight were 5 months (20 minutes – 35 months) and 6 kg (0.62-15.7 kg), respectively. The median dose of ICM per procedure was 3.9mL/kg (0.1 – 20.4mL/kg). The median time of follow-up TFT was 23 days (9-143 days). On follow-up, only one infant with Trisomy-21 developed new-onset hypothyroidism requiring treatment with levothyroxine (incidence rate of 1.0%). However, whether this was an association or causation could not be established. Conclusions: The risk of thyroid dysfunction after exposure to ICM during cardiac catheterization is low. It is likely unnecessary to routinely screen all patients for hypothyroidism post ICM exposure and can be limited to high-risk groups candidates.