Methimazole-induced cholestatic jaundice in an elderly hyperthyroid patient.

Background: Hyperthyroidism is a common disease in the elderly. Antithyroid medications such as methimazole are one of the few treatment options.

Case Summary: A 76-year-old white woman presented to the clinic with a 1-week history of fatigue, sleepiness, 7-pound weight loss, and tachycardia. Her blood work showed low levels of thyroid-stimulating hormone and high levels of free thyroxine. Due to persistence of her symptoms, she was hospitalized and started on methimazole 10 mg TID. Six weeks after receiving methimazole for the treatment of hyperthyroidism, she had severe jaundice and itching. Results of her liver function tests showed elevation of her alkaline phosphatase and liver transaminase levels, as well as hyperbilirubinemia, formed mainly of the conjugated fraction. Methimazole-induced cholestatic jaundice was diagnosed. Her symptoms gradually improved after discontinuation of the medication, and plasma bilirubin levels were near normal after 8 weeks without methimazole.

Conclusions: We report here a probable association between methimazole use and severe cholestatic jaundice in an elderly hyperthyroid patient. The patient's jaundice was reversed after drug discontinuation.