Toxic Thyroid Adenoma

Toxic adenoma is a solitary autonomously functioning thyroid nodule causing hyperthyroidism.

• Somatic activating TSHR (most) or GNAS mutations.
• Usually nodules over 3 cm cause thyrotoxicosis; risk of toxicity rises with size.
• Cancer risk is very low in hot nodules.

• Mild to moderate hyperthyroidism, palpitations, weight loss, tremor.
• Solitary palpable nodule, rest of the gland not enlarged.
• No eye signs.

• Low TSH, raised free T3 (and T4).
• Thyroid scan: single hot nodule with suppression of the rest of the gland.
• Ultrasound for size and features; biopsy not required for hot nodule.
• TSH receptor antibodies negative.

• Beta blocker for symptoms; methimazole 10 to 20 mg daily to achieve euthyroidism.
• Definitive: radioiodine (I 131 10 to 30 mCi, cure 80 to 90%, spares the suppressed tissue, low hypothyroidism rate), or hemithyroidectomy/lobectomy.
• Percutaneous ethanol injection or radiofrequency ablation for selected nodules.
• Antithyroid drugs alone do not cure.
• Follow thyroid function 6 weeks after therapy, then yearly.