Aspartate aminotransferase (AST) in blood

Aspartate aminotransferase (AST) in the blood is a difficult-to-pronounce phrase that denotes a special enzyme of the cell that actively participates in the normal exchange and interaction of almost all amino acids. AST is found in large quantities in cardiac tissues, as well as in liver cells, nervous tissue and kidneys. It is for this reason that almost all diseases associated with these organs require determining the level of aspartate aminotransferase in the blood. Aspartate aminotransferase (AST) in the blood is also one of the types of transaminases that transfer aspartic acid through molecules. It can be said that the well-known vitamin B6 is a coenzyme analogue of AST.

Reference values (norm) of AST activity in blood serum are 10-30 IU/l.

A fairly low level of the enzyme is considered normal, but if the tissue is damaged, aspartate aminotransferase (AST) in the blood gradually increases, being released from damaged cells. The level of AST in the blood increases as the tissue is damaged. If myocardial infarction is diagnosed, aspartate aminotransferase begins to accumulate in the bloodstream within 6-10 hours.

Aspartate aminotransferase (AST) in the blood can exceed the normal limit by five times and maintain such values for up to a week. High activity of this transaminase is a clear indicator of the extremely serious condition of the patient, in which an unfavorable outcome is possible. If AST increases gradually but persistently, this indicates that the infarction zone is expanding. Also, AST activity can be caused by necrotic phenomena in the liver.

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Why is aspartate aminotransferase measured in the blood?

This analysis is important and necessary to clarify possible diseases and pathologies, such as:

• All types of hepatitis and necrotic liver diseases;
• Degeneration of parenchymatous tissue into fibrous tissue – cirrhosis (alcoholism);
• Oncologic process in the liver, metastases;
• Emergency cardiac conditions – myocardial infarction;
• Autoimmune diseases, including hereditary diseases - Duchenne-Becker muscular dystrophy;
• Viral lesions of the lymphatic system, including mononucleosis;
• Cholestatic syndrome.

How to prepare for a test when AST is checked in the blood?

Taking any medication, sometimes even a herbal decoction, can distort the results of the study. Therefore, before checking the level and activity of AST, you should either stop taking the medication, or if this is impossible for some reason, provide information about the drug, its dose and time of administration to the doctor. Even simple and harmless at first glance valerian extract or vitamins, for example, vitamin A, can negate the accuracy and informativeness of the studies. In addition, it is necessary to take into account allergic reactions to specific medications; in women, pregnancy can distort the picture of laboratory tests for AST.

How is the analysis performed, how is aspartate aminotransferase (AST) determined in the blood? Only venous blood is used for the analysis. Apart from the pressure of the tourniquet, a slight tingling at the puncture site with a needle, there are no painful sensations - this is a routine analysis, the results of which are known within 6-12 hours.

Aspartate aminotransferase in the blood - what are the norms?

Average standards:

• Women – from 10 to 36 units/l;
• Men - from 14 to 20 units/l.

Too high AST is either a liver pathology, possibly viral in nature, or a liver reaction to acute intoxication as a result of alcohol intake, possibly narcotic drugs. Also, high AST transaminase values may indicate extensive or multiple tumors.

A slight excess of the normal limits is a chronic alcohol addiction, possibly cirrhosis. Also, a slight increase in aspartate aminotransferase may be due to hypervitaminosis - vitamin A. Heart attack, mononucleosis, pathologies of the pulmonary system or kidneys - the list goes on. The main thing to remember: aspartate aminotransferase (AST) in the blood is an important indicator of the condition of the tissues of human organs, and decoding the tests is the doctor's job.

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Causes of increased AST in the blood

Increased AST activity in the blood is observed in a number of diseases, especially when organs and tissues rich in this enzyme are affected. The most dramatic changes in AST activity occur when the heart muscle is affected. Enzyme activity is increased in 93-98% of patients with myocardial infarction.

In myocardial infarction, AST increases in the serum after 6-8 hours, reaches its maximum activity after 24-36 hours and decreases to a normal level by the 5th-6th day. Expansion of the myocardial infarction zone leads to the appearance of a second cycle of increased activity. The degree of increase in AST activity reflects the mass of the myocardium involved in the pathological process. Sometimes AST activity increases even before the appearance of electrocardiographic signs of myocardial infarction, and the absence of a decrease in its level after the 3rd-4th day of the disease is prognostically unfavorable. In myocardial infarction, AST activity in the blood can increase 2-20 times.

In angina pectoris, AST activity usually remains within normal limits. However, a number of authors indicate an increase in AST in severe coronary insufficiency in the first 24 hours after the attack and normalization on the 2nd, less often the 3rd day after the attack, as well as in long attacks of paroxysmal tachycardia.

AST also increases in acute hepatitis and other severe hepatocyte damage. Moderate increase is observed in mechanical jaundice, in patients with liver metastases and cirrhosis. The de Ritis coefficient, i.e. the AST/ALT ratio, is normally 1.33, below this value in liver diseases, and above it in heart diseases.

A number of indicators represent factors by which the value of the upper reference limit for AST is multiplied.

In clinical practice, the simultaneous determination of AST and ALT activity in the blood has found wide application; it provides much more clinical information about the localization and depth of the lesion, the activity of the pathological process; it allows predicting the outcome of the disease.