IMPE Abstracts

In the setting of iodine excess, organification of thyroglobulin is blocked, serving as a protective mechanism against hyperthyroidism. This phenomenon, the Wolff-Chaikoff effect, can result in persistent hypothyroidism. Excessive iodine exposure is usually iatrogenic, coming in the form of radiographic dyes, amiodarone, and povidone-iodine antiseptic solution. In March 2022, the US Food and Drug Administration (FDA) released a statement that at-risk children up to age 3 years should have thyroid studies monitored within three weeks of an exposure to iodinated contrast media. We set out to better understand baseline practices of thyroid monitoring following cardiac procedures and imaging at our large, urban hospital and pediatric cardiology referral center. Electronic health record (EHR) data were abstracted on patients less than 3 years who underwent a cardiac procedure or imaging between February 01, 2020 and December 31, 2021. Continuous variables were compared using Kruskal-Wallis rank sum test. Procedures were categorized as Major Cardiac Surgery, Cardiac CT or Catheterization, and Miscellaneous. 558 patients were identified. Patients were 47% female. Race as recorded in the EHR was 42% White, 11% Black, 4.3% Asian, and 42.2% other/unknown. Thyroid studies were monitored after procedure or imaging in 18.3%. In patients whose thyroid studies were monitored, 29% had cardiac CT or catheterization (Cath), 49% had a major cardiac surgery (MCS), and 20% had a non-cardiac miscellaneous procedure (Misc). Median TT3 was lower in the MCS group than in the Cath or Misc. groups (P= 0.018). Median TSH, TT4, and FT4 did not differ significantly based on procedure category (Table 1).

While persistent hypothyroidism following iodinated contrast exposure is uncommon, it is a known secondary effect that carries with it a risk to neurodevelopment in young children if unrecognized. Thyroid monitoring was performed following a procedure involving iodine in 18.3% of patients under 3 years of age who underwent cardiac procedure or imaging at a high-volume pediatric cardiology referral center. Patients who underwent a major cardiac surgery prior to thyroid monitoring had a lower median TT3 when compared to patients in Cath and Misc groups.