Graves' Disease in the Elderly: A Case of Fluctuating Hyperthyroidism and Hypothyroidism Resulting in Challenging Management.

A woman in her late 80s was diagnosed with Graves' disease (GD) following routine blood tests, which showed a thyroid-stimulating hormone of <0.005 mU/L, free thyroxine of 39 pmol/L, and TSH receptor antibodies of 9.8 IU/L. She denied adrenergic symptoms. Thyroid ultrasound revealed a 37 mm benign nodule in the left lobe. She had known atrial fibrillation and heart failure, as well as a history of toxic nodular goiter treated with partial thyroidectomy 50 years earlier. On examination, she presented with exophthalmos and pretibial myxedema, initially treated as cellulitis. She was started on carbimazole 15 mg; however, thyroid function tests were not monitored. Five months later, she was admitted to the hospital with symptomatic hypothyroidism and persistent bradycardia. Carbimazole was discontinued, and levothyroxine was initiated. Over the following four months, she was admitted three more times with alternating hypothyroidism and hyperthyroidism, accompanied by worsening cardiac complications. This case highlights the challenges of recognizing and managing GD and its complications in the elderly.