A Case of Propylthiouracil-Induced Hepatitis during Pregnancy

A 32-year-old with no pre-existing liver disease was diagnosed with Graves’ disease at week 4 of pregnancy. Thyroid-stimulating hormone was undetectable with elevated free thyroxine levels and positive thyroid receptor antibodies. She was started on a reducing regime of propylthiouracil (PTU). At week 20 in pregnancy, she became jaundiced. Initial bloods revealed: bilirubin 91 µmol/l, alanine aminotransferase 1,796 IU/l, alkaline phosphatase 200 IU/l, international normalized ratio 1.2, and albumin 33 g/l. A presumptive diagnosis of PTU-induced hepatitis was made. PTU was immediately discontinued and best supportive care instigated. Serum markers for autoimmune and viral hepatitis were negative, abdomen ultrasound, ferritin and caeruloplasmin were normal. Although her alanine aminotransferase began to fall, her bilirubin continued to rise, peaking at 378. Two weeks after PTU cessation she became thyrotoxic and was started on a reducing regime of carbimazole. Her thyroid function stabilized and liver function tests continued to improve with carbimazole stopped at week 32. Growth scans remained normal with delivery of a healthy baby at 38 weeks. This report highlights that good outcomes can be achieved in PTU-induced hepatitis in pregnancy. Patients on PTU should be warned of the potential risk of hepatic failure and advised to seek medical advice immediately if they develop jaundice.