Liver Function Test Lecture Notes PDF

 Is the largest gland of the body weighing 1.2-1.5 kg in an adult human. It is situated in the abdominal cavity , just below the diaphragm and has 2 lobes. The hepatic lobules are the structural and functional units of liver containing hepatocytes, arranged in the form of cords. Liver se...

 Is the largest gland of the body weighing 1.2-1.5 kg in an adult human. It is situated in the abdominal cavity , just below the diaphragm and has 2 lobes. The hepatic lobules are the structural and functional units of liver containing hepatocytes, arranged in the form of cords. Liver secretes bile which is alkaline, yellowish green fluid. It has no enzymes but help in emulsification of fats due to the presence of bile salts. FUNCTIONS OF THE LIVER 1 Synthetic functions: synthesis of plasma proteins,cholesterol, triacylglycerol and lipoprotein 2 Metabolic function: protein metabolism, ketogenesis, TCA cycle, production of ATP 3 Detoxification & excretion: ammonia to urea, bilirubin, cholesterol, drug metabolites. 4 Homeostasis: blood glucose regulation 5 Storage function: Vitamin A,D,K,B12 6 Production of bile salts WHY IT'S DONE Screening: They are non invasive yet sensitive modality for liver dysfunction. Pattern of disease: They are helpful to recognize pattern of various diseases. Like being helpful in differentiating between acute viral hapatitis and various cholestatic disorders and chronic liver disease. (CLD) Assess severity: They are helpful to assess the severity and predict the outcome of certain diseases like primary biliary cirrhosis. Follow up: They are helpful in the follow up of certain liver diseases and also helpful in evaluating response to therapy like autoimmune hepatitis ALT BLOOD TEST Other names: Alanine aminotransferase (ALT), Serum Glutamic-Pyruvic Transaminase (SGPT), GPT ALT stands for alanine transaminase. It is an enzyme found mostly in the liver. An ALT test measures the amount of ALT in the blood. ALT is found predominantly in liver , kidney(to a lesser extent ), heart and skeletal muscle injury or disease affecting liver cell will cause a release of this Hepatocellular enzyme into the blood stream, thus elevating serum ALT levels. Generally most ALT elevation are caused by liver disease. therefore, this enzyme is not only sensitive but also quiet specific in indicating Hepatocellular disease.  ALT is a cytoplasmic enzyme while AST is found in both cytoplasm and mitochondria. Serum ALT and AST are increased in liver damage. However, ALT is more sensitive and reliable for the assessment of LFT. When liver cells are damaged, they release ALT into the bloodstream. High levels of ALT in your blood may be a sign of a liver injury or disease. Some types of liver disease cause high ALT levels before you have symptoms of the disease. So, an ALT blood test may help diagnose certain liver diseases early. An ALT blood test is often part of a routine blood screening to check the health of your liver. The test may also help diagnose or monitor liver problems. WHY DO I NEED AN ALT BLOOD TEST? High levels of ALT in your blood can be due to damage or injury to the cells in your liver. An increased ALT level may indicate the following conditions: Alcohol-induced liver injury. Fatty liver disease (too much fat in your liver). Hepatitis (liver inflammation). Cirrhosis (scarring of the liver). Taking medications that are toxic to your liver. Liver tumor or liver cancer. Liver ischemia (not enough blood flow to your liver, which leads to death of liver tissue). ASPARTATE AMINOTRANSFERASE (AST) GLUT A MI C O X A L O A C E T A T E T RA N S A MI N A S E AST is measured in the evaluation of suspected coronary occlusive heart disease or suspected hepatocellular disease. When disease or injury affects the cells of these tissues causing cells lyses. AST is released and picked up by the blood and the serum level rises. the AST level rises within 6-10 hours after MI, peaks at 12- 48 hours and returns to normal in 3-4 days. A second rise in AST would indicate extension or progression of myocardial injury despite therapy. Myocardial injuries such as angina, pericarditis or rheumatic carditis do not increase AST levels.  Diseases that affect the hepatocyte cause elevated levels of this enzyme. In acute hepatitis AST levels can rise 20 times the normal value. In acute extrahepatic obstruction (eg. Gall stone) AST levels quickly rise to 10 times the normal and swiftly fall. In cirrhotic patient the level of AST depends on the amount of active inflammation.  The ratio of the serum aspartate to alanine amino- transferase levels (AST/ALT) is often used as a clue to the etiology of the underlying liver disease. This ratio is usually greater than 2.0 in alcoholic liver disease and less than 1.0 in patients with chronic hepatitis and chronic cholestatic syndromes. INCREASED LEVELS Heart diseases ( MI, cardiac catheterization,) Liver diseases ( hepatitis , cirrhosis, hepatic metastasis, drugs induced liver injury, hepatic surgery). Skeletal muscle diseases (trauma, multiple trauma , sever or deep burn, progressive muscular dystrophy). Other diseases ( acute hemolytic anemia, acute pancreatitis).