Endocrine Abstracts

JOINT2042

We present a case of severe T3 thyrotoxicosis in a 23-year-old female with Graves’ disease. The patient presented in August 2023 with weight loss despite increased appetite, tachycardia (up to 130/min), and peripheral tremors. Laboratory tests confirmed thyrotoxicosis. Ultrasonographic examination revealed a homogenous goiter, with a volume exceeding 50 ml, with marked vascularization, consistent with the typical features of Graves’ disease. The diagnosis was confirmed by high TRAB levels (36.94 UI/l) Initial treatment with Thiamazole (20 mg/day) triggered a mild allergic reaction (dermatitis) and was switched to propylthiouracil (PTU) 75 mg/day but this led to severe hepatotoxic reaction (liver enzymes elevated to 7xUNL). Despite switching to cholestyramine (20 mg/day), thyroid function remained poorly controlled, with persistently elevated T3 (on many occasions found to be over 600 ng/dl, reference range 35-193 ng/dl) and ongoing symptoms of thyrotoxicosis and Graves’ ophthalmopathy. Intravenous methylprednisolone (MTP) was initiated, reaching a total dose of 1750 mg along 3 months, which led to a reduction in T3 levels and allowed to resume thiamazole treatment. Despite this, thyroid function remained unstable with suppressed TSH and high T3. Heart rate remained poorly controlled despite 120 mg daily propranolol. Given the severity of her thyrotoxicosis, surgical treatment was considered but it was declined by two surgeons due to the increased bleeding risk associated with uncontrolled disease, the cardiac risks of severe T3 thyrotoxicosis and the possibility of postoperative tracheotomy. The patient continued with 40 mg Thiamazole daily and 120 mg propranolol, but thyroid function remained inadequately controlled for T3 while fT4 reached target. In November 2024 she had an uneventful total thyroidectomy after preoperative treatment (10 days) with Lugol’s iodine (15 drops/day), methylprednisolone (16 mg/day) and Thiamazole (40 mg/day). The gland was symmetrically enlarged (max diameter 9 cm (right) and 10 cm (left)). Both recurrent laryngeal nerves showed normal parameters on intraoperative nerve monitoring and postoperative voice was unaffected. One month later, the patient achieved euthyroidism, with normal T3/TSH while on replacement therapy with Levothyroxine 100 µg/day. In conclusion, this case highlights the aggressive nature of T3 thyrotoxicosis, its resistance to conventional treatments, and the challenges posed by multiple medication allergies. It underscores the importance of a multidisciplinary approach in managing severe, refractory hyperthyroidism.