RESUMEN
BACKGROUND: Autoimmune diseases including thyroid. disorders, type 1 diabetes and celiac disease are commoner in persons with Down's syndrome compared with the general population. Coexistent type 1 diabetes and hyperthyroidism in Down's syndrome is however not commonly reported in literature. OBJECTIVE: To report a case of a lady presenting with Graves' disease and type 1 diabetes at the same time. CLINICAL PRESENTATION: We report the case of a 22- year-old lady with Down's syndrome who presented with weight loss, polyuria and polydipsia. Physical examination revealed typical dysmorphicfacies of Down's syndrome and a goitre. Laboratory data revealed hyperglycaemia (random plasma glucose-331 mg/dl). She also had biochemical evidence in keeping with hyperthyroidism and markedly elevated thyroid peroxidase antibodies (>1087.0 IU/ml). She improved after rehydration, insulin therapy and antithyroid drugs. CONCLUSION: Coexisting autoimmune diseases may present in patients with Down's syndrome. We advocate for routine screening for diabetes and thyroid dysfunction in ersons with Down's syndrome.