Blood test for liver function is one of the health checkup items, of which alanine aminotransferase (ALT, formerly known as glutamic aminotransferase) and aspartate aminotransferase (AST, formerly known as glutamic aminotransferase) are important indicators. In clinical practice, we often see people with abnormal liver function labs who are at a loss. So what exactly are the factors that can cause elevated serum aminotransferase, please check the number and find the cause. I. Infection factors This includes viral infections, bacterial infections and infections by other pathogenic microorganisms. Take viral infections as an example, the most important one is hepatitis B, followed by hepatitis A, hepatitis C, hepatitis D and hepatitis E. Hepatitis B and C are mainly transmitted through blood, body fluids and sexual intercourse and can become chronic, causing repeated elevation of transaminases in patients. Hepatitis A and E are mainly transmitted through the gastrointestinal tract, do not turn chronic, and are mostly due to unclean diet with diarrhea. Other common viral factors are EBV and cytomegalovirus. Patients tend to first show signs of upper respiratory tract infection, such as fever, cough, sneezing, runny nose, and sore throat. When you find yourself with elevated transaminases, the first thing to ask yourself is whether you originally had hepatitis B or C? If not, have you recently had diarrhea? Have you eaten hygienically lately? Have you recently caught a cold? Alcoholic liver damage Drinking alcohol is another important factor that causes elevated transaminases. The chemical composition of alcohol is ethanol, which is mainly transformed into acetaldehyde and acetic acid through the metabolism of liver dehydrogenase. Both ethanol and acetaldehyde are highly reactive oxides, and acetaldehyde in particular is more toxic and has a direct destructive effect on liver cells. The higher the degree of alcohol and the higher the intake, the more serious the liver damage. So, when transaminases are elevated, ask yourself if you have been drinking recently. If so, then it is likely that drinking is to blame. Third, fatty liver Fatty liver is a disease caused by the excessive accumulation of fat in the liver for a variety of reasons, the most common cause is excess nutrition. The patient is mostly overweight, likes to eat fatty foods and has a reluctance to be active. Serum aminotransferase levels usually show mild to moderate elevation, rarely exceeding 200 U/L, but may last longer and can be recurrent. When you experience this, ask yourself if you are physically overweight. If so, have your blood lipids and liver ultrasound checked again. If there are both elevated blood lipids and positive ultrasound imaging results, it is likely that you have a fatty liver. Fourth, autoimmune disease Autoimmune disease is a disease in which the body’s immune function is disrupted, causing damage to its own tissues. It can be manifested as mild or moderate elevation of serum transaminases repeatedly for a long time. Since autoimmune disease is a systemic disease, it is usually accompanied by other organ diseases, such as diabetes, hyperthyroidism or rheumatoid arthritis. If a middle-aged woman or older has persistently elevated transaminases and usually has itchy skin and joint pain, please go to the hospital to check the serum autoantibodies, if the autoantibodies are positive, it is likely to be autoimmune hepatitis. Five, chemical (drug) factors The most common chemical factors in daily life is contact with volatile organic compounds, such as benzene, formaldehyde, permethrin, etc.. Clinically we often see, patients due to renovation of new houses painted, or closed spraying mosquito killer and caused by the example of transaminase elevation. Paint contains benzene, insecticide containing permethrin, can be inhaled through the respiratory tract caused by liver damage. Most of the drug-induced aminotransferase elevation occurs within 7 to 30 days after the use of drugs. Therefore, when you encounter elevated transaminases, you should also ask yourself: Have you recently been in contact with toxic chemicals? If you have taken medication recently, please check whether the drug has any hepatotoxicity. Sixth, metabolic diseases are caused by the lack of certain metabolic enzymes in the human body, mostly congenital factors, to children and adolescents are more common. For example, glucose-6-phosphatase deficiency can cause impaired glucose metabolism and glycogen accumulation disorder; copper cyanidin deficiency can cause impaired copper metabolism and produce hepatomegaly. Serum aminotransferases may rise repeatedly over time. This type of disease is difficult to diagnose and requires careful screening. If there are similar patients in the family, that is an important clue. VII. Malignant tumors of the liver include primary hepatocellular carcinoma and metastatic carcinoma from other organs, mostly seen in middle-aged and elderly people over 50 years old. In the process of elevated serum aminotransferases, there may be significant elevation of methemoglobin. Due to tumor compression, bile excretion is not smooth, so it is usually accompanied by elevation of bilirubin, among which direct bilirubin is the main one. If you are a middle-aged or elderly patient, please don’t forget to have an ultrasound, CT and MRI of the liver, which are very helpful for the diagnosis of liver tumor.