SUN-495 Rapid Resolution of Hyperthyroidism Induced Hepatic Dysfunction with Methimazole

Background: Hepatic dysfunction in the setting of hyperthyroidism is difficult to diagnose and poses a challenge in therapy, since the classic medications used are potentially hepatotoxic. Clinical case: A 51-year-old female patient presented with fatigue, palpitations and tremors. BP 146/65 mmHg, HR 111 bpm and Temp 97.8 F. She was severely thyrotoxic with 3 + DTRs, tremors, enlarged thyroid gland with bruit on auscultation, clear lungs and no lower extremities edema. Blood tests showed TSH <0.003 IU/ml (0.450-5.330 IU/ml), Free T4 5.33 ng/dL (0.45-1.80 ng/dL), Free T3 > 30.0 pg/mL (2.3-4.2 pg/mL). Liver enzymes showed elevation in transaminases with ALT 319 IU/L (7-40 IU/L), AST 330 IU/L (7-40 IU/L) normal total Bilirubin 0.7 mg/dL (0.1-1.5 mg/dL) and Alkaline phosphatase 65 IU/L (40-200 IU/L). Transaminases were also elevated 3 weeks prior to presentation and this was extensively worked up with no identifiable etiology to explain the liver dysfunction. She was started on beta blocker therapy and admitted to the ICU. She had no clinical or echocardiographic evidence of cardiac dysfunction and remained hemodynamically stable. She was started on Methimazole 45 mg daily. The patient improved clinically and a pronounced decline in transaminase levels was documented in the first 72 hours. She was discharged home on day 3 of admission. On follow up visit her transaminases were found to have completely normalized within 14 days. Discussion: The diagnosis of elevated transaminases in hyperthyroidism is a challenge. This is due to the possibility of multiple etiologies including decreased cardiac output and/or liver congestion, concomitant primary liver disease or more specifically autoimmune hepatic disease such as primary biliary cirrhosis. (1-2). Incidentally Methimazole has been associated with transient asymptomatic transaminitis typically during the first three months of therapy (3). Our case indicates, that methimazole can be used in patients with a presumed diagnosis of hyperthyroidism induced hepatotoxicity after all possible etiologies are ruled out. Hyperthyroidism as the cause of liver dysfunction can only be entertained after all those etiologies are ruled out and upon resolution of transaminase elevation in conjunction with improvement in the hyperthyroid state itself, as was demonstrated in this case. Conclusion: Methimazole can be safely used in patients with severe hyperthyroidism and elevated liver enzymes when all other etiologies of liver dysfunction have been ruled out. References: 1. Khemichian S, Fong TL. Hepatic dysfunction in hyperthyroidism. Gastroenterol Hepatol (N Y). 2. Elias RM, Dean DS, Barsness GW. Hepatic dysfunction in hospitalized patients with acute thyrotoxicosis: a decade of experience. 3. LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. Bethesda (MD): Methimazole