Endocrine Abstracts

JOINT337

Introduction: Autoimmune disorders are common in patients with Down syndrome (DS), particularly thyroid diseases. In DS patients, hyperthyroidism occurs less frequently than hypothyroidism, is mostly caused by Graves’ disease, typically manifests between late childhood and early adulthood, shows no sex predominance, and often requires definitive treatment. There is a lack of consensus on the role of total thyroidectomy in the treatment of Graves’ disease in DS patients due to potential anesthetic and surgical risks associated with craniofacial anomalies and short neck. However, surgery may be necessary when Iodine-131 therapy is contraindicated or refused by the family.

Case Presentation: We report the case of a 19-year-old female patient affected by DS and Graves’ disease. Medical history included glycogen storage disease type Ia (GSD Ia), a rare autosomal recessive disorder of carbohydrate metabolism, characterized by fasting hypoglycemia, lactic acidosis, hepatomegaly, and risk of developing hepatocellular adenomas. Hyperthyroidism first manifested at the age of 11, with symptoms of fatigue and weight loss. TSH receptor antibody testing was positive (22 IU/l), while no goiter or exophthalmos were observed. She was started on methimazole therapy, up to 20 mg/day, which was discontinued after 3 years due to biochemical remission, without side effects. After 1 year of euthyroidism, Graves’ disease relapsed and methimazole therapy was resumed. Given the recurrence of hyperthyroidism and the need for long-term methimazole therapy, particularly in the context of chronic liver disease, a definitive treatment was considered. Following discussion with the family, nuclear radiologist and endocrine surgeon, total thyroidectomy was preferred over Iodine-131 therapy. Because of GSD Ia-related risk of hypoglycemia and lactic acidosis, perioperative management included infusion of dextrose-containing solution and frequent monitoring of blood glucose and lactate. Total thyroidectomy was performed with a conventional surgical approach. No significant bleeding or recurrent laryngeal nerve paresis occurred, however, the patient developed transient hypocalcemia (down to 7.8 mg/dl), which resolved within 1 month. She was discharged on a liquid levothyroxine formulation due to fasting limitation, requiring frequent high-carbohydrate meals with uncooked corn-starch supplementation. Histological examination documented diffuse hyperplasia with interstitial lymphocytic infiltrates.

Conclusion: To our knowledge, there is limited evidence in the literature regarding the preferred definitive treatment for Graves’ disease in individuals with Down syndrome. Our case suggests that total thyroidectomy may be a safe and effective treatment option for these patients. A multidisciplinary discussion—including endocrinologists, pediatricians, endocrine surgeons, nuclear radiologists, as well as the patient’s and family’s preference—is required.