Toxic Multinodular Goiter

Toxic multinodular goitre (Plummer disease) is hyperthyroidism from autonomously functioning nodules in a multinodular goitre.

• Second commonest cause of hyperthyroidism after Graves disease, more in iodine deficient regions and the elderly.
• Mechanism: activating TSHR or GNAS mutations in nodules.
• Iodine loading (contrast, amiodarone) can trigger thyrotoxicosis.

• Atrial fibrillation, weight loss, palpitations, heart failure, osteoporosis (often apathetic in the elderly).
• Nodular goitre, possible compressive symptoms.
• No ophthalmopathy or dermopathy.

• Suppressed TSH, raised free T3 and T4 (T3 toxicosis common).
• TSH receptor antibodies negative.
• Radioiodine uptake scan: multiple hot and cold areas, uptake normal or mildly raised.
• Ultrasound; biopsy of cold nodules; CT for retrosternal extension.

• Beta blocker (propranolol 20 to 40 mg three times daily, bisoprolol) for symptom control.
• Antithyroid drugs (methimazole 10 to 30 mg daily) to render euthyroid before definitive therapy; they do not induce remission.
• Definitive: radioiodine (I 131 15 to 30 mCi, effective, goitre shrinks 30 to 50%), or thyroidectomy for large or compressive goitre, suspicious nodules.
• Long term low dose methimazole 2.5 to 10 mg is an option in frail patients.
• Anticoagulate AF per CHA2DS2 VASc, bone protection, hypothyroidism monitoring after treatment.