Aspartate aminotransferase (AST) in the blood

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

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

Normally, a fairly low level of enzyme is considered, but if the tissue is damaged, aspartate aminotransferase (AST) in the blood gradually rises, being released from the damaged cells. How seriously damaged tissue, so increases the level of AST in the blood. If a myocardial infarct is diagnosed, aspartate aminotransferase begins to accumulate in the bloodstream for 6-10 hours.

Aspartate aminotransferase (AST) in the blood can exceed the limit of the norm at times five times and keep such indicators for up to a week. The 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 the AST grows gradually, but stubbornly, it indicates that the zone of the infarction expands. Also, the activity of AST can be caused by necrotic phenomena in the liver.

[1], [2]

Why is aspartate aminotransferase in the blood?

This analysis is important and necessary for clarifying possible diseases and pathologies, such as: 

• All types of hepatitis and necrotic liver disease; 
• The degeneration of parenchymal tissue into fibrotic tissue - cirrhosis (alcoholism); 
• Onkoprotsess in the liver, metastases; 
• Urgent cardiac conditions - myocardial infarction; 
• Autoimmune, including hereditary diseases - Duchenne-Becker's myodystrophy; 
• Viral lesions of the lymphatic system, including mononucleosis; 
• Cholestatic syndrome.

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

The intake of any medicine, sometimes even herbal decoction, can distort the results of the study. Therefore, before you check the level and activity of the AST, you either need to stop taking the medication, and if this is impossible for some reason, tell the information about the drug, its dose and time of reception to the doctor. Even simple and harmless at first glance, valerian extract or vitamins, for example, vitamin A, can cross out the accuracy and informative nature of the research. In addition, it is necessary to take into account allergic reactions to specific medications, women can distort the picture of laboratory tests on AST.

How is the analysis performed, how is aspartate aminotransferase (AST) determined in the blood? The material for analysis is only venous blood. In addition to the pressure of the tourniquet, a slight tingling at the puncture site with a needle, there are no painful sensations - this is an ordinary analysis, the results of which are known after 6-12 hours.

Aspartate aminotransferase in the blood - what are the norms?

Average statistical standards:

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

Too elevated AST is either a pathology of the liver, possibly of a viral nature, or a hepatic reaction to acute intoxication due to alcohol intake, possibly narcotic drugs. Also, the high value of transaminase AST can talk about extensive or multiple tumors.

A slight excess of the norm is a chronic dependence on alcohol, possibly cirrhosis. Also, a small increase in aspartate aminotransferase may occur with hypervitaminosis - vitamin A. Infarction, mononucleosis, pathology of the pulmonary system or kidneys - the list goes on. The main thing is to remember: aspartate aminotransferase (AST) in the blood is an important indicator of the state of the tissues of human organs, and the analysis of the analyzes is the work of the doctor.

[3], [4], [5], [6], [7], [8]

The reasons for the increase of AST in the blood

An increase in the activity of AST in the blood is observed with a variety of diseases, especially in the defeat of organs and tissues rich in this enzyme. The most dramatic changes in the activity of AST occur when the cardiac muscle is affected. The enzyme activity in 93-98% of patients with myocardial infarction was increased.

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

With angina, ACT activity, as a rule, remains within the normal range. However, a number of authors indicate an increase in AST in the severe form of coronary insufficiency in the first 24 hours after the attack and normalization on the 2nd, rarely the 3rd day after the attack, as well as with prolonged attacks of paroxysmal tachycardia.

AST increases also in acute hepatitis and other severe lesions of hepatocytes. Moderate increase is observed with mechanical jaundice, in patients with metastases to the liver and cirrhosis. The De Ritis coefficient, that is, the AST / ALT ratio, is normally 1.33, with liver disease below this value, and with heart disease - higher.

A number of indicators are multipliers multiplied by the value of the upper reference limit for the AST.

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