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Thyroid Nodule Post-RAI — RACP Adult Medicine MCQ

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ModerateEndocrinology & DiabetesThyroid Nodule Post-RAIRACP Adult Medicine

A 38-year-old woman with a history of Graves' disease treated with radioactive iodine 5 years ago now presents with a new painless thyroid nodule. Ultrasound shows a 2.2 cm hypoechoic nodule with microcalcifications. TSH is elevated at 12 mIU/L (she has been non-compliant with levothyroxine). What is the concern?

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Correct answer: B — The nodule is likely a colloid cyst

While RAI treatment itself does not significantly increase thyroid cancer risk at therapeutic doses, a new thyroid nodule with suspicious ultrasound features (hypoechoic, microcalcifications) in ANY patient requires FNA biopsy regardless of prior treatment history. The elevated TSH from levothyroxine non-compliance may stimulate thyroid tissue growth. The suspicious ultrasound features (not the RAI history) are the primary driver for investigation. Bethesda classification guides subsequent management.

Reference: eTG – 2025 – Endocrinology; ATA – 2015 – Thyroid Nodule Guidelines