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.

在健康和疾病中，甲状腺和肝脏之间存在复杂的关系。肝在甲状腺激素的活化，失活，运输和代谢中起着至关重要的生理作用。相反，甲状腺激素会影响肝细胞的活动和肝代谢。甲状腺功能减退症中观察到的血清肝酶异常可能与脂质代谢受损，肝脂肪变性或甲状腺功能减退症引起的肌病有关。严重的甲状腺功能减退症可能具有生化和临床特征，例如高氨血症和腹水，可模仿肝功能衰竭。由于氧化应激，胆汁淤积或成骨活性增强，甲状腺功能亢进症中的肝功能检查通常也异常。抗甲状腺药物相关的肝毒性是罕见的事件，可能主要与特异机制有关，从轻度的肝细胞损害到肝功能衰竭。丙硫氧嘧啶引起的肝损伤通常比甲巯咪唑引起的肝损伤更为严重。另一方面，在慢性丙型肝炎，肝硬化，肝细胞癌和胆管癌等肝脏疾病中可以发现甲状腺异常。特别地，在丙型肝炎病毒感染的患者中经常发现自身免疫性甲状腺疾病。这些患者，尤其是在已经存在甲状腺自身免疫的情况下，在单独使用新的抗病毒药物之前或单独使用信息素-α或联合利巴韦林治疗期间和之后，都有甲状腺功能低下或甲状腺毒症的风险，尤其是在已经存在甲状腺自身免疫的情况下。本综述总结了与甲状腺疾病相关的肝脏异常及其治疗方法，