Enzymes are specific proteins that play the role of biological catalysts in the body. Enzymes are examined to identify diseases, carry out differential diagnostics, assess the dynamics of the course of the disease, determine the effectiveness of treatment and the degree of recovery; with a prognostic purpose.
Norms of ALT and AST in the blood
Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) are special proteins (transaminase enzymes) that are found inside organ cells and are involved in the exchange of amino acids (the substances that make up proteins). Selective tissue specialization allows us to consider them as marker enzymes: ALT - for the liver, AST - for the myocardium.
Normally, the content of ALT and AST in the blood depends on gender. In a healthy adult woman, the level of ALT and AST does not exceed 31 U / L. In men, normal ALT does not exceed 45 U / L, and AST 47 U / L. Depending on the age of the child, the level of ALT and AST changes, while the ALT content should not be higher than 50 U / L, AST - 140 U / L (from birth to 5 days) and not more than 55 U / L for children under 9 years old. Depending on the equipment used for the study, it is possible to vary the norms and reference values of the enzyme level. An increase in the rate of renewal of enzymes, cell damage lead to an increase in the level of transaminases in the blood.
Aspartate aminotransferase (AST) is widespread in human tissues (heart, liver, skeletal muscles, kidneys, pancreas, lungs, etc.). The level of ACT in the blood rises in a number of diseases, especially with damage to organs and tissues rich in this enzyme. The most dramatic changes in the activity of the enzyme are observed with damage to the heart muscle. With myocardial infarction, the amount of AST in the blood can increase by 2-20 times.
Alanine aminotransferase (ALT) is found in skeletal muscle, liver, heart. In the heart muscle, it is significantly less than ACT. In acute hepatitis, regardless of its etiology, the aminotransferase activity increases in all patients. With infectious hepatitis, there is a sharp increase in the content of the enzyme in the blood. A moderate increase in the amount of ALT is noted in obstructive jaundice, in patients with liver metastases and cirrhosis.
Increasing ALT and AST
In medicine, the simultaneous determination of the activity of ACT and ALT in the blood is used, which carries more information about the localization and depth of the lesion, the activity of the pathological process; allows you to predict the outcome of the disease. De Ritis coefficient, i.e. the ACT / ALT ratio, normally equal to 1.33, is lower than this value in liver disease, and higher in heart disease. In acute viral hepatitis, the level of transaminases rises 10-15 days before the onset of jaundice in hepatitis A, and for many weeks in hepatitis B, and they rise simultaneously, but ALT is much higher. An increase in the activity of ALT and ACT can also be detected in practically healthy carriers of the surface antigen of hepatitis B, which indicates the presence of outwardly asymptomatic active processes in the liver.