Cholestatic jaundice - an enigmatic form of "hepatic" thyrotoxicosis

Background and Aim: Asymptomatic abnormalities of liver function tests are common in hyperthyroidism. However, severe cholestatic jaundice with markedly elevated transaminases is rarely described in thyrotoxicosis as seen in our case. Case report: A 28-year-old female presented with yellowish discoloration of urine and sclera for 15 days followed by generalized itching of the body without a history of pain abdomen, fever, myalgia, arthralgia, pale stools, hematemesis, melena, or altered behavior. There was no history of alcohol use, over-the-counter drugs, complementary and alternative medicines, or ATT intake. She was a known case of hyperthyroidism for 5 years and had stopped tab neomercazole for the last 6 months. On examination, icterus, fine tremors of the hands, tachycardia, and thyromegaly were present. Systemic examination was unremarkable. Investigations showed Hb 15 gm%, TLC 9320/mm3, DLC N77/L14 Platelet count 1.69 lacs/mm3 Bilirubin 17/13 mg/dl, AST/ALT 1358/1359 IU, ALP 457 IU, Protein/Albumin 8.9/3.9 gm/dl, Urea/Creatinine 37/0.5, Na/K 138/4.9, INR 1.36, HbsAg/Anti HCV/HIV I/II were Nonreactive, Anti HAV Ig M, Anti HEV Ig M and Ig M Anti Hbc antibody were negative. Free T3, T4, and TSH- 9.22/5.49/0.01 were suggestive of hyperthyroidism. Anti TPO antibody was 62.49 (elevated), ANA, ASMA, Anti LKM1, AMA M2- negative. Ig G was 11g/L. USG abdomen was normal. MRCP didn't show evidence of PSC or other hepatobiliary pathology. Liver biopsy suggestive of maintained architecture, lobular inflammation, mild portal triaditis with focal bile ductular proliferation. Hepatocytes show mild cholestasis with feathery degeneration and Mallory denk bodies. No steatosis, ballooning degeneration, or fibrosis is seen. The patient was started on neomercazole, propranolol, and prednisolone for thyrotoxicosis. After 2 weeks of therapy, her bilirubin fell to 8.1 and AST/ALT/ALP to 124/217/302. Conclusions: Hepatic involvement of thyrotoxicosis can present like autoimmune or viral hepatitis-like injury and early identification and prompt treatment is life-saving. Response with anti thyroid drugs is virtually diagnostic of this entity.