Drug-induced liver injury caused by iodine-131

Hepatotoxicity of iodine-131 ablation for post-surgical differentiated thyroid cancer patients with hepatitis B virus infection

OBJECTIVE

Radioiodine (Iodine-131, ¹³¹I) ablation is a standard treatment for differentiated thyroid cancer (DTC) after thyroidectomy. Hepatotoxicity is a rare side effect of ¹³¹I, and little information is available on the hepatotoxicity of ¹³¹I ablation for post-surgical DTC patients with hepatitis B virus (HBV) infection.

METHODS

We performed a retrospective study of 94 post-surgical DTC patients between November 2012 and August 2015 in our hospital. All the patients had been screened for HBV infection and divided into HBV group and non-HBV group. Clinical data were compared between the two groups.

RESULTS

14 patients with HBV infection and 80 patients without HBV infection were analyzed. The baseline characteristics of the two groups had no statistical differences. Incidence of hepatotoxicity was higher in HBV group than in non-HBV group and HBV infection was confirmed as a risk factor of hepatotoxicity by univariate and multivariate regression analysis.

CONCLUSION

Post-surgical DTC patients with HBV infection were prone to hepatotoxicity by ¹³¹I ablation treatment. Physicians should pay more attention to the liver function of patients at risk.

The interplay between thyroid and liver: implications for clinical practice

A complex relationship exists between thyroid and liver in health and disease. Liver plays an essential physiological role in thyroid hormone activation and inactivation, transport, and metabolism. Conversely, thyroid hormones affect activities of hepatocytes and hepatic metabolism. Serum liver enzyme abnormalities observed in hypothyroidism may be related to impaired lipid metabolism, hepatic steatosis or hypothyroidism-induced myopathy. Severe hypothyroidism may have biochemical and clinical features, such as hyperammonemia and ascites, mimicking those of liver failure. Liver function tests are frequently abnormal also in hyperthyroidism, due to oxidative stress, cholestasis, or enhanced osteoblastic activity. Antithyroid drug-associated hepatotoxicity is a rare event, likely related mainly to an idiosyncratic mechanism, ranging from a mild hepatocellular damage to liver failure. Propylthiouracil-induced liver damage is usually more severe than that caused by methimazole. On the other hand, thyroid abnormalities can be found in liver diseases, such as chronic hepatitis C, liver cirrhosis, hepatocellular carcinoma, and cholangiocarcinoma. In particular, autoimmune thyroid diseases are frequently found in patients with hepatitis C virus infection. These patients, especially if thyroid autoimmunity preexists, are at risk of hypothyroidism or, less frequently, thyrotoxicosis, during and after treatment with interpheron-alpha alone or in combination with ribavirin, commonly used before the introduction of new antiviral drugs. The present review summarizes both liver abnormalities related to thyroid disorders and their treatment, and thyroid abnormalities related to liver diseases and their treatment.

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.

Recent Advances in the Histopathology of Drug-Induced Liver Injury

Drug-induced liver injury (DILI) is constantly changing as new drugs are approved and as new herbals and dietary supplements (HDS) reach the market. The pathologist plays a key role in the evaluation of DILI by classifying and interpreting the histologic findings considering patients' medical history and drug exposure. The liver biopsy findings may suggest alternative explanations of the injury and additional testing that should be performed to exclude non-DILI causes. Recent reports of iatrogenic liver injury are reviewed with attention to immunomodulatory and antineoplastic agents as well as reports of injury associated with HDS use.