Liver abnormalities and endocrine diseases

The liver and its pleotropic functions play a fundamental role in regulating metabolism, and is also an inevitable target of multiple metabolic disorders. The numerous and constant relationships and feedback mechanisms between the liver and all endocrine organs is reflected by the fact that an alteration of one oftentimes results in the malfunction of the other. Hypo- and hyperthyroidism are frequently associated with hepatic alterations, and thyroid diseases must be excluded in transaminase elevation of unknown cause. Drugs such as propylthiouracil, used in the treatment of hyperthyroidism, may induce liver damage, and other drugs such as amiodarone, carbamazepine, and several chemotherapeutic agents can lead to both thyroid and liver abnormalities. Liver diseases such as hepatitis, hepatocellular carcinoma, and cirrhosis may cause altered levels of thyroid hormones, and alcoholic liver disease, both due to the noxious substance ethanol as well as to the hepatic damage it causes, may be responsible for altered thyroid function. Both excess and insufficiency of adrenal function may result in altered liver function, and adrenocortical dysfunction may be present in patients with cirrhosis, especially during episodes of decompensation. Again an important player which affects both the endocrine system and the liver, alcohol may be associated with pseudo-Cushing syndrome. Sex hormones, both intrinsic as well as extrinsically administered, have an important impact on liver function. While oestrogens are related to cholestatic liver damage, androgens are the culprit of adenomas and hepatocellular carcinoma, among others. Chronic liver disease, on the other hand, has profound repercussions on sex hormone metabolism, inducing feminization in men and infertility and amenorrhoea in women. Lastly, metabolic syndrome, the pandemia of the present and future centuries, links the spectrum of liver damage ranging from steatosis to cirrhosis, to the array of endocrine alterations that are features of the syndrome, including insulin resistance, central obesity, and hyperlipidaemia. Clinical practice must integrally evaluate the effects of the intricate and tight relationship between the liver and the endocrine system, in order to better address all manifestations, complications, and prevent deterioration of one or the other organ-system.