Case report: Severe cholestatic jaundice associated with hyperthyroidism treated with methimazole

RATIONALE: We present a case of a 43-year-old female patient diagnosed with hyperthyroidism. This study aims to demonstrate the rare association between hyperthyroidism and severe cholestatic jaundice, and the effectiveness of methimazole treatment. PATIENT CONCERNS: The patient developed severe jaundice, a typically mild symptom in most hyperthyroidism cases. DIAGNOSIS: The severe jaundice was suspected to be a result of cholestasis induced by hyperthyroidism, with other potential causes such as drug-induced or autoimmune liver dysfunction being ruled out. OUTCOMES: The patient was effectively treated with methimazole. Outcomes: Treatment with methimazole alleviated the severe cholestatic jaundice and restored normal thyroid function. LESSONS: The specific mechanism of cholestasis as a secondary complication of hyperthyroidism remains unclear, and there are no specific biochemical markers for cholestasis caused by this hormonal disease. This case underscores the possibility of severe jaundice as a clinical manifestation of hyperthyroidism, and highlights antithyroid drug treatment as an effective strategy for managing severe cholestatic jaundice.