Propylthiouracil-induced liver failure and artificial liver support systems: a case report and review of the literature

Drug-Induced Liver Injury: A Unique Presentation of Single-Dose Administration of Propylthiouracil

Antithyroid drug-induced severe liver injury is an uncommon but serious complication. We hereby delineate the case of a 38-year-old female who presented to the emergency department for an impending thyroid storm. After initiation of a single dose of propylthiouracil, her liver enzymes went into the thousands. She was subsequently admitted to the intensive care unit. Propylthiouracil was discontinued and corticosteroids were initiated with the resolution of her elevated liver enzymes. On follow-up, her liver function was at its baseline and thyroid hormone levels were under control. We hope this report will encourage clinicians to cast a broad differential diagnosis in patients presenting with liver injury in the acute setting. Furthermore, it is imperative to raise awareness regarding the ever-increasing list of pharmacologic agents that can perpetuate drug-induced hepatotoxicity.

Challenges in early identification of causes and treatment of cholestasis in patients with hyperthyroidism: a case report and literature review

Early identification of the causes of cholestasis is important for appropriate management of patients with hyperthyroidism. We report a patient who had hyperthyroidism and severe cholestasis after methimazole (MMI) treatment. The patient was diagnosed as having MMI-induced cholestatic hepatitis. Treatment with MMI was stopped at admission to hospital. However, his serum total bilirubin (TBil) level rose from 410.5 µmol/L to 519.9 µmol/L and prothrombin time activity (PTA) dropped from 81.0% to 52.2% in 10 days. To prevent further deterioration of his liver function, plasma exchange was performed three times, and dexamethasone (10 mg, intravenously) was used each time. His PTA rose to 101% and his TBil continued to increase to 669.8 µmol/L after plasma exchange. He was subsequently diagnosed as having thyrotoxicosis-induced cholestasis and treated with radioactive iodine (380 MBq) 2 weeks after admission. His hyperthyroidism was significantly relieved, but the TBil level further increased to 776.8 µmol/L. Three weeks after admission, oral prednisone (30 mg/day) was used in this patient. Subsequently, his TBil levels gradually decreased and his liver function almost normalized within 3 months. We discuss the literature on cholestasis in the context of hyperthyroidism.

Involvement of gap junctions in propylthiouracil-induced cytotoxicity in BRL-3A cells

Gap junctions (GJs), which are important plasma membrane channels for the transfer of signaling molecules between adjacent cells, have been implicated in drug-induced liver injury. However, the influence and the underlying mechanisms of GJs in propylthiouracil (PTU)-induced hepatotoxicity are unclear. In the present study, distinct manipulations were performed to regulate GJ function in the BRL-3A rat liver cell line. The results indicated that the toxic effect of PTU in BRL-3A cells was mediated by GJ intercellular communication, as cell death was significantly attenuated in the absence of functional GJ channels. Furthermore, the specific knockdown of connexin-32 (Cx32; a major GJ component protein in hepatocytes) using small interfering RNA was observed to decrease necrosis, intracellular PTU content and the level of reactive oxygen species (ROS) following PTU exposure. These observations demonstrated that suppressing GJ Cx32 could confer protection against PTU-induced cytotoxicity through decreasing the accumulation of PTU and ROS. To the best of our knowledge, the present study is the first to demonstrate the role and possible underlying mechanisms of GJs in the regulation of PTU-induced toxicity in BRL-3A rat liver cells.

Liver diseases and thyroid functional status

The liver is closely related to the thyroid function. On one hand, many liver diseases can cause abnormal thyroid function, such as hepatitis B virus (HBV) infection, hepatitis C virus (HCV) infection, liver cirrhosis, and nonalcoholic fatty liver disease. Thyroid dysfunction is also commonly caused by interferon alpha treatment for anti-HBV or HCV therapy. On the other hand, thyroid diseases such as hyperthyroidism or hypothyroidism can result in abnormal liver function. In addition, liver injury can also be frequently caused by antithyroid drugs or levothyroxine of over conventional doses. The causal relationship between abnormal liver function and thyroid dysfunction remains unclear.