Caption: Photo courtesy of Chen Yuanwen Director Hospital
According to statistics from the World Health Organization, 350 million people worldwide suffer from liver disease, and more than 1 million people die from it every year. As a country with a heavy burden of liver disease, the prevalence of viral hepatitis caused by viral infection in my country has declined in recent years, but the number of non-alcoholic fatty liver disease and alcoholic liver disease related to bad living habits has increased year by year, and the number of young people trend.
The liver is responsible for important physiological functions such as metabolism, detoxification, and synthesis. No matter what the cause of liver disease, it will lead to abnormal liver function in patients, and these abnormalities can be reflected by testing liver function. March 18 is the 22nd “National Liver Love Day”. Chief physician Chen Yuanwen, director of the Department of Gastroenterology of East China Hospital, taught everyone to interpret the liver function test sheet and take good care of their liver.
Director Chen Yuanwen introduced that the liver function test sheet usually contains three types of indicators, namely, indicators of liver cell damage, indicators of liver secretion and excretion, and indicators of liver synthesis and reserve function.
Indices of hepatocyte injury
The indicators of hepatocyte injury included alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase and glutamyl transpeptidase.
The normal range of alanine aminotransferase (ALT) is 0U/L~40U/L. This index is the main item for diagnosing hepatocyte parenchymal damage, and the level of the index can sensitively reflect changes in the condition.
However, ALT lacks specificity. Fatigue, drinking, colds, emotional factors and other reasons can cause changes in the permeability of liver cell membranes, but the resulting increase in transaminase is generally not higher than 60U/ L. Once the ALT value is higher than 80U/L, it has diagnostic value and needs to go to the hospital for treatment.
The normal range of aspartate aminotransferase (AST) is 0U/L~40U/L. AST is widely distributed in many tissues and organs in the body and consists of the isoenzymes ASTS and ASTM.
The significance of elevated AST is similar to ALT in the diagnosis of hepatitis. In general, AST does not increase as much as ALT. Once the AST value is higher than the ALT value, it indicates that the degree of liver cell damage and necrosis is more serious. At this time, the determination of isoenzymes is of greater significance. Only AST is increased in mild liver damage, and ASTM is significantly increased in severe liver damage.
The normal reference value of alkaline phosphatase (ALP) is 30U/L~90 U/L, which is composed of more than 3 kinds of isozymes. ALP is excreted through the biliary tract, so liver disease, excretory dysfunction, or biliary tract disease and bone disease can increase ALP.
The normal value of γ-glutamyl transpeptidase (γ-GT) is 3U/L~50U/L. γ-GT is only mildly to moderately elevated in acute hepatitis, chronic active hepatitis and decompensation of liver cirrhosis. In obstructive jaundice, transpeptidase in blood can be significantly increased, even more than 10 times normal. In addition, γ-GT is also significantly elevated in alcoholics, which is helpful for the diagnosis of alcoholic liver disease.
Liver secretion and excretion function index
Bilirubin is an index reflecting liver metabolism and excretion function. Under normal circumstances, bilirubin needs to be processed by the liver and then excreted out of the liver through the biliary tract. The bilirubin that has been processed by the liver is called direct bilirubin, the one that has not been processed by the liver is called indirect bilirubin, and the sum of the two is called total bilirubin.
When the total bilirubin value exceeds 17.1 μmol/L, it is called jaundice, which often indicates liver, gallbladder, and pancreas problems. If there is anemia at the same time, hemolysis should be considered. When the liver cells are damaged, the total bilirubin can be increased, and the indirect bilirubin is mainly increased, indicating that the detoxification ability of the liver is reduced.
However, the liver has a strong compensatory ability to metabolize bilirubin, so total bilirubin and indirect bilirubin may not be elevated in the early stage of the disease.
Liver Synthesis and Reserve Function Index
The liver is the only organ that synthesizes albumin (ALB) in the human body, so the level of ALB reflects the anabolic function of the liver and the Reserve function. Serum albumin decreases in any liver disease that results in insufficient protein intake, decreased albumin synthesis, or protein loss (nephrotic syndrome, protein-losing enteropathy).
Precautions for liver function test
“There are many precautions for liver function test, and everyone needs to strictly abide by them.” Director Chen Yuanwen reminded, “Liver function test is a Blood is drawn on an empty stomach, and the fasting time is generally 8 to 12 hours. Therefore, you should not eat after 21:00 the night before the examination, and avoid eating high-fat, high-protein, and carotene- and lutein-rich foods for dinner. Ensure adequate sleep. On the day of the examination, do not eat breakfast, drink water, or do physical exercise or strenuous exercise. After arriving at the hospital, you should rest quietly for 20 minutes before taking a blood test.”
Chen Yuanwen emphasized that drinking alcohol will affect the indicators of transaminase in liver function, and you should not drink alcohol the night before the examination. At the same time, try to avoid liver function tests during intravenous infusion or within 4 hours of medication. If physical conditions permit, it is best to stop the drug 3-5 days before the liver function test.
Correspondent Wu Qimin Xinmin Evening News reporter Zuo Yan