Endocrine Abstracts

JOINT3949

Introduction: Pediatric Graves’ disease (PGD) is marked by hyperthyroidism and antithyroid receptor antibodies (TRAb). Low antithyroid treatment (ATD) remission rates, side effects and poor adherence require alternative therapies.

Objective: To describe outcome to radioiodine treatment (RAI) in PGD at a single institution.

Material and Methods: Retrospective analysis of 35 PGD patients followed between 2006 and 2024 treated with RAI. Data describing outcome and adverse effects were retrieved. RAI dose was calculated by formula using thyroid size by palpation or sonography and 24 hours-RAI uptake (100-250 µ Ci).

Results: Hispanic PGD cohort, 89% females, with a median age of 12 years (y) (range (r): 2–17.2). Thyroid disease was familial in 46% and 14% had other autoimmune conditions. Two had Down syndrome; one had osteogenesis imperfecta. All but one received ATD in a titration regimen and one with hepatic failure (autoimmune hepatitis) underwent RAI as first option. Median ATD duration was 1.3 y (r: 0.1–6.5). RAI was indicated for 14 patients (40%) due to exacerbation under low-dose ATD, 11 (31%) for adverse reactions, 9 (26%) for poor compliance, and 1 (3%) for flare-up after ATD discontinuation. Median age at RAI indication was 14.6 years (r: 5.8–19.9y). Median goitre size at indication was 45g (r: 30–80g). Median RAI dose was 10 mCi (r: 5–20) for the first dose, equivalent to 0.26 mCi/g thyroid tissue (r:0.25-0.36). Three patients required a second dose for persistent hyperthyroidism at a mean of 0.7years (SD ± 0.14); the mean total dose of RAI was 0,4 mCi/g thyroid tissue (SD ± 0,14). All achieved hypothyroidism (elevated TSH, normal/low thyroid hormones) at a median time of 0.3 years (r: 0.1–5.1) after RAI. Beta-blockers were used in all but two patients for transient tachycardia post-RAI and 8 patients needed ATD for transient hyperthyroidism (23%). No adverse events were reported. Median post-RAI follow-up was 3 y (r: 0.4–11.6).

Conclusions: RAI was an effective and save definitive treatment for PGD patients who presented adverse reactions or failure to ATD with high chances to achieve hypothyroidism in 3-4 months.