Coexistence of Hyperthyroidism and Type 1 Diabetes in a Child with Down Syndrome: A Rare Autoimmune Endocrine Disorder

Down syndrome (DS) is a common chromosomal disorder associated with intellectual disability and various medical issues, including autoimmune endocrinopathies. The prevalence of Type 1 diabetes mellitus (T1DM) in DS is higher than in the general population, with thyroid disorders commonly observed. Hyperthyroidism, although rare, can occur in children with DS, and its coexistence with T1DM is an uncommon but important clinical phenomenon. A 10-year-old girl with DS presented with progressive anterior diffuse struma, weight loss, increased thirst, and frequent urination. Laboratory tests confirmed T1DM with elevated glucose and HbA1c levels, and hyperthyroidism with elevated thyroglobulin and anti-TPO antibodies. The presence of glutamic acid decarboxylase 65 antibodies further supported the diagnosis. The patient was started on insulin therapy and thiamazole for hyperthyroid management, with stable clinical progress during hospitalization. The association between autoimmune disorders, including T1DM and thyroid dysfunction, is well-documented in DS. Children with DS have a heightened risk of developing multiple autoimmune conditions, making early screening for thyroid dysfunction crucial at the time of T1DM diagnosis. This case emphasizes the need for vigilant monitoring of endocrine function in DS patients, particularly for concurrent autoimmune diseases. Early detection and management of autoimmune endocrinopathies are essential in children with DS, especially when T1DM and hyperthyroidism coexist. Regular thyroid monitoring, including TSH and TPO antibodies, can prevent complications and promote optimal health outcomes. Early intervention is key to supporting the overall development of affected children.