Hot Thyroid Nodule: Autonomous Function
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Question
On a thyroid scan, a solitary 'hot' (hyperfunctioning) nodule with suppression of the surrounding thyroid tissue indicates that the nodule is:
- AAutonomously functioning — producing thyroid hormone independent of TSH
- BHighly likely to be malignant and requires surgical excision
- CA thyroid cyst with hemorrhage
- DA parathyroid adenoma
Show the answer and explanation
A. Autonomously functioning — producing thyroid hormone independent of TSH
A 'hot' nodule on thyroid scan is one that shows increased tracer uptake relative to surrounding thyroid tissue, often with suppression of the rest of the gland. Hot nodules are autonomously functioning — they produce thyroid hormone independent of TSH stimulation, which suppresses TSH and the rest of the thyroid. Importantly, autonomous (hot) nodules are almost never malignant (<1% risk). Cold (hypofunctioning) nodules carry a higher risk of malignancy (~15%) and require FNA.
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