Hyperthyroidism-associated Liver Disease

　　1. Causes of disease

　　1. The direct action of thyroid hormones has an important role in the metabolism, transformation, excretion, and synthesis of thyroid-binding globulin.

　　2. Hypoxia and ischemia of liver cells caused by the hypermetabolic state of hyperthyroidism.

　　3. Disruption of liver energy metabolism.

　　4. Complications such as infections in patients with hyperthyroidism.

　　2. Pathogenesis

　　1. The direct action of thyroid hormones has an important role in the metabolism, transformation, excretion, and synthesis of thyroid-binding globulin. 20% of T4 and T3 are degraded in the liver, combined with glucuronic acid or sulfate, and excreted into the small intestine through bile. Long-term excessive transformation and metabolism of thyroid hormones increase the burden on the liver and may directly produce toxic effects on the liver.

　　2. Under the hypermetabolic state of hyperthyroidism, the oxygen consumption of liver cells increases while the liver blood flow does not increase accordingly, leading to hypoxia and ischemia of liver cells.

　　3. Disruption of liver energy metabolism. During hyperthyroidism, various metabolic rates in the body increase, leading to increased consumption of nutrients. The liver glycogenolysis increases, and the lack of protein and vitamins. In addition, due to the disorder of the patient's gastrointestinal absorption function, the absorption of nutrients is reduced, leading to insufficient nutritional supplementation and deficiency, which reduces the liver's own protective function.

　　4. Congestive heart failure caused by hyperthyroid cardiomyopathy leads to venous congestion in the liver, aggravating liver damage.

　　5. Other complications in hyperthyroid patients include infections, which have an adverse effect on the liver during stress, or liver damage due to autoimmune reactions.

　　There is currently no information on complications. The patient's diet should be light and easy to digest, with an emphasis on eating more vegetables and fruits, and a reasonable diet. Pay attention to adequate nutrition. In addition, patients should also pay attention to avoiding spicy, greasy, and cold foods.

　　Liver function damage caused by hyperthyroidism itself includes symptoms such as jaundice, elevated liver enzymes, anorexia, aversion to oil, diarrhea, and other digestive system symptoms. Due to the lack of specific manifestations, it should be distinguished from viral hepatitis and liver damage caused by antithyroid drugs, as the mechanisms and treatment methods of these three types of liver damage are different. Therefore, early and clear diagnosis is particularly important.

　　1. The following are some differences between hyperthyroidism accompanied by hepatitis and liver damage caused by hyperthyroidism:

　　1. Irrelevant to the severity of hyperthyroidism.

　　2. Obvious symptoms of hepatitis such as anorexia and aversion to oil in the digestive system.

　　3. Positive markers of hepatitis infection.

　　4. Ineffectiveness of antithyroid treatment, etc.

　　Secondly, the diagnosis of antithyroid drug-induced liver damage is usually made by exclusion.

　　1. Clinical laboratory tests show evidence of liver damage.

　　2. Temporal association between medication and liver damage, that is, liver damage occurs after medication.

　　3. No serological evidence of hepatitis virus infection or autoimmune hepatitis.

　　4. No evidence of chronic liver disease.

　　5. No other known hepatotoxic drugs were used simultaneously.

　　6. Liver function improves or recovers after discontinuation of medication.

　　7. Pathology shows mononuclear cells and lymphocytes infiltrating the liver lobules.

　　8. Repeated use of the same drug can cause liver damage again.

　　It is generally believed that liver damage caused by antithyroid drugs is more common within the first 3 months of medication. The liver damage caused by PTU is mainly characterized by varying degrees of liver cell necrosis, while the liver damage caused by MMI is mainly characterized by intrahepatic cholestasis, that is, cholestasis in liver cells and/or bile ducts. The former is mainly manifested by an increase in transaminases, while the latter is mainly manifested by an increase in bilirubin.

　　Prevention first, regular follow-up, and liver function tests before medication for patients with hyperthyroid liver disease who have a history of hepatitis are necessary. Since drug-induced liver damage usually occurs within the first 3 months of treatment, it is necessary to regularly follow up with patients within the first 3 months of treatment, monitor liver function, and inform patients that if they experience symptoms similar to hepatitis such as loss of appetite or jaundice, they should seek medical attention immediately.

　　1. Liver function tests:When liver cells die, GOT and GPT are released into the blood after the liver cell membrane is damaged (under normal circumstances, GOT and GPT are not only present in liver cells but also in cells of other parts of the body, such as muscle cells, brain cells, myocardial cells, etc., so an increase in GOT and GPT does not necessarily mean liver damage. It is just that the content of GOT and GPT is the highest in liver cells). Therefore, some people believe that it is more appropriate to call them 'liver inflammation indicators' than 'liver function indicators'. The levels of GOT and GPT are not necessarily related to the severity and prognosis of liver disease. Sometimes the immune system clears the virus by causing liver cell necrosis, and at this time, the levels of GOT and GPT will rise, so we cannot simply judge whether the liver is damaged based on GOT and GPT alone.

　　2. Hepatitis markers:When liver cells die, GOT and GPT are released into the blood, so some people believe that it is more appropriate to call them 'liver inflammation indicators' than 'liver function indicators'. The levels of GOT and GPT are not necessarily related to the severity and prognosis of liver disease. Sometimes the immune system clears the virus by causing liver cell necrosis, and at this time, the levels of GOT and GPT will rise, so we cannot simply judge whether the liver is damaged based on GOT and GPT alone.

　　3. Abdominal ultrasound examination:Blood tests can reflect the condition of a patient's liver function, but they cannot provide clear information for liver cirrhosis or liver cancer. Especially for some patients with liver cirrhosis and liver cancer, their liver function test results may still be within the normal range, and they may have no symptoms at all. Therefore, it is necessary to combine blood tests with ultrasound examinations.

　　4. Blood alpha-fetoprotein (AFP/fetal protein) test:Alpha-fetoprotein (AFP/fetal protein) is an important indicator for the detection of liver cancer. Alpha-fetoprotein/AFP is a manifestation of active liver cell growth, so a small number of normal people and pregnant women can be higher than normal. The liver cells of the fetus are actively growing, and the alpha-fetoprotein/AFP secreted is significantly higher than that of normal people (hence it can be called fetal protein). AFP can pass through the placental barrier, causing the mother's blood AFP to increase. When liver cells are actively growing during the recovery period of some hepatitis patients, AFP can also increase, but generally the degree of increase is mild or the duration is short. When the alpha-fetoprotein/AFP increases significantly or progressively, it may indicate liver cancer. It is important to consult a specialist doctor and go to the hospital for an early check-up.

　　1. It is recommended to adopt a diet high in protein, vitamins, low in sugar and fat. Do not eat or eat less animal fat and sweets (including sugary drinks). Eat more green vegetables, fruits, and foods rich in fiber, as well as lean meats, river fish, and soy products, and do not eat snacks or have a snack before bedtime.

　　2. Foods that patients with liver disease should eat daily include corn, rice cakes, noodles, bread, peanuts, walnuts, soy products, lotus seeds, jujube, green vegetables, winter melon, dried yellow croaker, dried cuttlefish, mushrooms, lean pork, pork kidneys, sheep and goat stomachs, chicken and duck gizzards, pigeon meat, crucian carp.

　　1. The treatment principle for liver damage caused by hyperthyroidism is to control hyperthyroidism mainly. At this time, the daily dosage of antithyroid drugs should be appropriately reduced, as large doses of drugs are more likely to cause liver damage and cannot improve the remission rate of hyperthyroidism. At the same time, liver function should be closely monitored, and medication should be stopped if liver damage continues to progress.

　　2. Protect the liver, reduce jaundice, and avoid drugs that may damage the liver, such as antipyretic and analgesics and estrogens, which can cause liver damage, possibly increasing serum thyroid hormone levels. Therefore, when hyperthyroid patients take certain drugs, they may promote hepatotoxic effects.

　　3. For patients with mild hyperthyroidism and liver damage, thioamide antithyroid drugs can be used. The author believes that for patients with chronic liver disease or poor liver function after taking medication, radioactive iodine or surgical treatment should be preferred.