AST (AST, aspartate aminotransferase, AST, SGOT, Aspartate aminotransferase)

What may affect the results

An increase in AST levels can be observed even in healthy people if the rules for preparing for the analysis are not followed. For example, blood should not be donated if during the day the patient experienced severe emotional distress, heavy physical exertion, underwent fluorography, X-ray examination or any physiotherapeutic procedures, ultrasound or rectal examinations of any spectrum. The result can be affected by the intake of alcohol and a number of medications, in particular, antitumor and choleretic drugs, antibiotics, barbiturates, contraceptives, sedatives, vitamin A and others, as well as recent heart surgery.

Reasons for increased AST levels

A high titer of AST may indicate pathology of the hepatobiliary tract, which is accompanied by the destruction of hepatocytes:

• hepatitis (infectious, alcoholic, ischemic, drug);
• fatty hepatosis;
• cirrhosis;
• autoimmune cholangitis;
• primary and secondary tumors in the liver.

High levels of AST are observed against the background of other diseases:

• heart failure;
• heart attack;
• pancreatitis;
• muscle dystrophy;
• celiac disease;
• kidney pathologies.

An increase in AST titer is observed after intense strength training, massive injuries, burns, and ketoacidosis. The concentration of AST in the blood increases when taking certain dietary supplements and medications (statins, barbiturates, acetylsalicylic acid).

Aspartate aminotransferase (in blood serum)

Blood for research is taken from a vein.
Usually, the level of another enzyme, alanine aminotransferase (ALT), is simultaneously determined, since the de Ritis coefficient (AST/ALT ratio) is considered informative for many liver conditions. You can take a blood test for AST (AST, aspartate aminotransferase, AST, SGOT, Aspartate aminotransferase) at the nearest INVITRO medical office.
A list of offices where biomaterial is accepted for laboratory research is presented in the “Addresses” section. Interpretation of study results contains information for the attending physician and is not a diagnosis. The information in this section should not be used for self-diagnosis or self-treatment. The doctor makes an accurate diagnosis using both the results of this examination and the necessary information from other sources: medical history, results of other examinations, etc.

ALT and AST: what are these tests?

ALT and AST - these abbreviations can often be seen in blood tests for biochemistry. What do they mean? What can they tell the doctor? Vasilisa Vladimirovna Ishchenko, a gastroenterologist at the Expert Clinic Kursk, answers our questions.

— Vasilisa Vladimirovna, what do the abbreviations ALT and AST mean?

- ALT, or alanine aminotransferase, is an endogenous enzyme produced by liver cells - hepatocytes. Its content in blood serum is insignificant. The highest concentration of ALT is found in the liver, so this enzyme is a specific marker of diseases of this organ. In addition, small amounts of ALT can be found in the kidneys, cardiac muscle, skeletal muscle, and pancreas.

AST, or aspartate aminotransferase, is also an enzyme from the group of transaminases that is involved in the metabolism of amino acids. Contained mainly in the liver, myocardium, nervous tissue, skeletal muscles, in smaller quantities in the kidneys, pancreas, spleen, and lung tissue.

When cells are damaged under the influence of infectious or toxic factors, energy metabolism in cells changes. Due to impaired permeability of cell membranes, components of the cytoplasm and disintegrated intracellular structures, including enzymes, enter the blood serum. As a result, the level of ALT and AST in the blood increases. This complex of disorders is called cytolytic syndrome.

— What will the ALT and AST indicators tell about in a biochemical blood test?

— Normally, the concentration of transaminases and their ratio to each other in the blood plasma are constant values. They reflect the balance of formation and release of these enzymes. In addition, this balance indicates the normal course of physiological destruction of aged cells (apoptosis). Deviations from the norm in the levels of ALT and AST and changes in their ratio are observed in pathological processes.

The degree of increase in the activity of these enzymes allows us to judge the severity of the cytolytic syndrome. However, these indicators do not always indicate the severity of organ damage and do not allow the doctor to judge the prospects for the development of the disease. Therefore, along with the analysis of ALT and AST, specialists usually prescribe a set of laboratory and instrumental examination methods, and also monitor the level of enzymes over time.

— In what cases are these tests recommended?

— Data on the level of ALT and AST may be important for such nonspecific symptoms as general weakness, decreased performance, lack of appetite, nausea, vomiting, abdominal pain, flatulence, yellowing of the skin and mucous membranes. These indicators must be determined to diagnose diseases and assess liver function.

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— What are the reasons for increased ALT and AST in the blood?

— Acute and chronic viral, toxic hepatitis, autoimmune diseases, fermentopathy, liver cirrhosis, tumor processes and metastases in the liver, infectious mononucleosis, pulmonary embolism, poliomyelitis, malaria, leptospirosis — in many pathological conditions we observe an increase in the level of these enzymes in the blood. Also, ALT and AST levels increase during myocardial infarction. Small short-term changes in their levels can be observed during heavy physical activity.

I would like to note that an important diagnostic indicator is the ratio between ALT and AST (the so-called de Ritis coefficient). This coefficient helps us distinguish, for example, viral hepatitis from alcoholic liver damage, myocardial infarction from liver diseases.

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— What could be associated with a decrease in ALT and AST levels in the blood?

— With vitamin B6 deficiency, severe liver cirrhosis, pancreatic pathologies, and renal failure (especially in patients on hemodialysis).

— How do the levels of ALT and AST in the blood change during pregnancy?

- Since the liver during this period detoxifies the body not only of the mother, but also of the fetus, an increase in the level of these enzymes can be observed.

— Vasilisa Vladimirovna, is preparation required for taking the test for ALT and AST? If so, which one?

- Of course it is required. Blood from a vein must be donated in the morning on an empty stomach (last meal 12 hours before the test). On the eve of the test, you should avoid heavy physical stress, changes in diet, and consumption of alcoholic beverages. Half an hour before blood sampling, you should also refrain from smoking.

I would like to emphasize that determining only the level of ALT and AST is not always sufficiently informative, so most often doctors prescribe them in combination with other biochemical indicators.

Would you like to read about other analyses? You will find articles about them in our laboratory diagnostics section

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Interviewed by Sevilya Ibraimova

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For reference:

Ishchenko Vasilisa Vladimirovna

Graduate of the Faculty of Medicine of Kursk State Medical University in 2015.

In 2021, she completed her internship in the field of Internal Medicine and underwent retraining in gastroenterology.

Currently holds the position of gastroenterologist at the Expert Clinic Kursk. Reception is conducted at the address: st. Karl Liebknecht, 7.

Normal indicators

Units of measurement: U/l.
Reference values:

For what indications is the test prescribed?

Observing certain diseases in a patient, the doctor can send him for a biochemical analysis of AST:

• Kidney failure
• Injuries to the chest and abdominal cavity,
• All liver damage
• Diseases of the cardiovascular system,
• Infections,
• Malignant tumors
• In preparation for surgery,
• Skin allergies,
• Jaundice,
• Chronic pancreatitis,
• Long-term treatment with chemicals and antibiotics,
• and other factors.

What do increased indicators mean?

A significant increase in AST activity is observed in myocardial infarction, insufficient blood circulation, shock, hypoxia, acute viral or toxic hepatitis, necrosis or damage to liver cells.
A moderate increase in AST activity can be detected in liver cirrhosis, obstructive jaundice, metastases, acute pancreatitis, ischemic or hemorrhagic stroke, with damage to skeletal muscles, after injuries or surgical interventions. In children, protein activity may increase in the presence of inflammatory processes in the body. An increase in aspartate aminotransferase concentrations is sometimes observed during pregnancy.

The use of hepatotoxic drugs or drugs that cause cholestasis (slowdown or complete cessation of bile secretion) can also provoke an increase in AST. Usually this condition is regarded as temporary.

Indications

An AST test can be recommended by a therapist, pediatrician, hepatologist, oncologist, surgeon, gastroenterologist, or cardiologist. The main reason for prescribing the study are symptoms of liver damage, which include:

• yellowing of the sclera and mucous membranes;
• skin itching;
• stool discoloration;
• darkening of urine;
• intoxication of the body (weakness, fatigue, nausea);
• bitter taste in the mouth, bloating, constipation as a manifestation of digestive tract dysfunction.

Liver tests, including AST, are taken by people at risk of developing liver disease. The test is prescribed in the following situations:

• previous hepatitis;
• unfavorable family history;
• taking hepatotoxic drugs;
• overweight;
• diabetes;
• alcohol abuse;
• contact with persons sick with viral hepatitis.

Transaminase indicators are important not only at the stage of primary diagnosis, but are also used to monitor the condition of patients with already diagnosed diseases, tracking the dynamics of the development of pathology and assessing the effectiveness of treatment.

The study is prescribed to persons with cardiovascular pathology. A high level of aspartate aminotransferase in the blood indicates serious damage to the heart muscle (in acute failure, heart attack), which is used in the differential diagnosis of acute life-threatening conditions.

Importance of liver enzymes

The content of the article

A separate class of enzymes are transferases, catalysts for the transfer of molecular residues and functional groups from molecule to molecule.

Transferases are involved in the transformation of nucleic acids and amino acids, lipids and carbohydrates. The most significant liver enzymes are considered to be ALT and AST, which perform several tasks at once.

• Molecular intracellular synthesis ensures sufficient liver functionality.
• Enzymatic diagnostics, carried out by measuring the degree of enzyme activity in the blood. The reliability of this method is based on the fact that liver enzymes in a healthy person are contained inside the cell, leaving it only after the death of the cell itself.
• The prognostic role of enzymes is associated with the characteristics of their dynamics in the blood, which directly depends on the nature of the course and severity of the disease.
• The medicinal role of enzymes is to use special enzyme preparations when they are deficient in the body.

AST functions

Aspartate aminotransferase is one of the key enzymes that catalyzes the reversible transfer of the α-amino group between aspartate and glutamate and, as such, is an important enzyme in amino acid metabolism.

At the macro level, this transport pathway influences the overall metabolism of amino acids and fats (fatty acids). It also plays a partial role in detoxification (urea cycle) and gluconeogenesis. [, ]

At the micro level, a direct chemical reaction that AST accelerates to convert an amino acid (aspartate) and acid (alpha-ketoglutarate) into another acid (oxaloacetate) and amino acid (glutamate). This conversion is vital for other metabolic processes such as the urea cycle, the glucose cycle and breakdown (glycolysis). [, ]

Why is an ALT test done?

The endogenous enzyme ALT serves as a reliable marker of liver tests - liver pathologies in diagnostic laboratory practice. Alanine aminotransferase is formed due to intracellular synthesis, so it is present in the blood in small doses.

Blood test for ALT

in a healthy person it shows a minimum value. Diseases or damage to the liver cause the death of its cells, and the intracellular liver enzyme ALT is released into the blood, which, along with other indicators, is a fairly informative indicator of disease processes. Any deviation of the enzyme indicator from the standard range, especially upward, is an indisputable sign of an incipient liver disease or an extensive process of its destruction

Elevated ALT levels may also be observed in pregnant women, during a heart attack, and in certain pathological conditions. An increase in the dose of ALT in the blood is observed before the manifestations of jaundice, which allows for early diagnosis of liver diseases.

How does the level of alanine aminotransferase in hepatitis depend on gender?

Russian scientists, having examined 320 people, including both sick people and healthy people (control group), found that in women with chronic hepatitis, the ALT indicator in 78.6% of cases does not correspond to the severity of the disease. Some patients even had normal alanine aminotransferase levels.

In men, the number of cases of hepatitis not accompanied by an excess of the concentration of this enzyme was only 21.4%, that is, the difference between the sexes is 3.7 times. Moreover, even with approximately the same severity of the disease, in women this figure was 1.5 times lower.

The female body has great potential to combat liver pathology, so if a representative of the fairer sex has clear signs of “liver problems,” then one test

for alanine aminotransferase is not enough - it may not be informative. At a minimum, you still need to undergo an ultrasound of the liver.

In order to get a real picture of the functioning of the liver, it is necessary to carry out other liver tests, then it is possible to more accurately say whether a woman has this pathology or not. Representatives of the fair sex often experience a latent course of chronic hepatitis, when symptoms of liver damage appear later, in the presence of pronounced, sometimes irreversible, changes. In addition, they are characterized by a more rapid restoration of normal ALT levels after Botkin’s disease, which is also associated with the physiological characteristics of the female body.

All these factors must be taken into account when examining men and women for the presence of liver pathologies.

Dependence of alanine aminotransferase levels on gender in viral hepatitis

ALAT norm

with various types of hepatitis it can increase 20 or even 100 times. In this case, the cause of this pathology (viruses, poisoning, hemolysis of red blood cells) does not play a role.

• In Botkin's disease, an increase in this biochemical indicator can be observed even before the appearance of jaundice and other clinical symptoms. Also, the level of ALT in the blood
  may be increased for some time after recovery, returning to normal (women - 31 U/L; men - 45 U/L) after two to three weeks.
• With “syringe” viral hepatitis , especially those with a chronic and protracted course (CVH), this indicator can constantly fluctuate either down or up. Sometimes it depends on the stage of the infectious process, and in some cases such jumps are difficult to explain.
• Mechanical (obstructive) jaundice also causes sudden changes in ALT concentration. With this pathology, the level
  of alanine aminotransferase in the blood can rise to 600 U/L in one day, and then spontaneously return to normal within about two days.

If obstructive jaundice is due to primary liver cancer, the concentration of alanine aminotransferase remains consistently high.