RÉSUMÉ
RATIONALE: This study reports the first case of congenital hypothyroidism (CH) and alpha thalassemia in a child in China, with anemia and muscle damage as the main manifestations. Analyzing and studying this case is of great significance in reducing missed and misdiagnosed CH and will provide a clinical strategy for treating these patients. PATIENT CONCERNS: Child, female, 2 years and 7 months old, the child appeared dispirited, had poor appetite, shallow complexion, reduced activities with anemia, elevated muscle enzymes, height, and growth retardation. DIAGNOSES: The child was diagnosed with CH with alpha thalassemia. INTERVENTIONS: The patient was treated with levothyroxine sodium and anemia correction. OUTCOMES: The children's current spirit, appetite, red face, normal limb activity, physical development, and intelligence were significantly better than those of normal children of the same age. CONCLUSIONS: CH with alpha thalassemia, especially anemia and muscle damage as the main manifestations, has not been reported. Administration of levothyroxine sodium is effective in correcting anemia in patients with CH and alpha thalassemia. LESSON: Due to CH and alpha thalassemia, there are no specific symptoms and they are prone to missed diagnosis and misdiagnosis. Therefore, patients with anemia and elevated muscle enzyme levels should be routinely tested for thyroid function to diagnose them early and provide proper treatment to avoid negative consequences.