A blood test for AST is a complex biochemical test that allows you to determine the amount of aspartate aminotransferase (intracellular endocrine enzyme) in tissues nervous system, skeletal muscles, heart, liver, kidneys and other organs. If the decoding of AST reveals an increased content of aspartate aminotransferase in the tissues of the body, this makes it possible to draw conclusions about the presence of pathological disorders.
Indications
AST analysis is used for the following purposes:
- To monitor the effectiveness of therapeutic measures aimed at treating liver diseases.
- AST is often compared with the results of other tests, such as total bilirubin and protein, alkaline phosphatase (ALP) to help determine the specific form of liver disease.
- To detect liver damage. Typically, the test is part of a general analysis of liver function or is prescribed in conjunction with an alanine aminotransferase (ALT) test. AST and ALT are the two most accurate indicators of liver damage.
In addition to the above points, a blood test for AST is used to monitor the health of patients using medications that are potentially toxic to the liver. If the AST level increases relative to normal, the patient may be prescribed treatment based on other medications.
The analysis is most often recommended for suspected myocardial infarction. The fact is that it is one of the earliest markers that help detect damage to the heart muscle. In addition, with the help of decoding AST during biochemical analysis, it becomes possible to diagnose and monitor other pathologies of the heart muscle, as well as deviations in the development of skeletal muscles and diseases of the hepatobiliary system.
This study is also prescribed for symptoms of liver disorder: fatigue, weakness, loss of appetite, bloating and pain in the abdomen, attacks of nausea and vomiting, yellowing of the whites of the eyes and skin, itching, light-colored stools, dark-colored urine.
In addition, the analysis is necessary if there are factors that increase the likelihood of liver disease: recent contact with hepatitis infection or a previous illness, diabetes or excess weight, hereditary predisposition to liver disease, excessive alcohol consumption, taking medications that can damage the liver.
Preparation
To begin with, we note some factors that may affect the results of studies of AST activity. First of all, these are heavy physical activity carried out shortly before taking the sample, chylosis, hemolysis in the blood sample (excess of fat microparticles in it), alcohol consumption and taking a number of medications (anti-tuberculosis drugs, chlorpropamide, opioids, erythromycin, methyldopa, pyridoxine, sulfonamides , dicumarol, as well as large doses of vitamin A, acetaminophen, salicylates). It has also been proven that in some patients, liver damage and, as a result, an increase in the concentration of AST in the blood can be provoked by long-term use of dietary supplements. In this regard, it is imperative to inform your doctor about taking nutritional supplements in addition to all other medications.
In view of the above, before the study it is recommended:
- Limit physical activity (hard work, sports, etc.).
- Plan your last meal 8 hours before the test.
- The day before the examination, it is prohibited to drink alcoholic beverages, as well as eat fatty and fried foods.
- Blood for this study is not donated immediately after a rectal examination, radiography, ultrasound, fluorography, or physiotherapeutic procedures.
Also, in order to get the most accurate indicators, you need to stop taking medications 1-2 weeks before the study. If the patient cannot fulfill this condition for any reason, then in the referral for examination the doctor must certainly indicate which specific medicines and what doses he takes.
Norm
When testing blood for women, the AST norm ranges from 31 to 35 U/L. The norm for men ranges from 41 to 50 units/l. As for children, the norm for them is no more than 75 units/l (under the age of one month) and no more than 60 units/l from 2 to 12 months of age. In children from one to 14 years of age, the levels are less than 45 units/l.
If there is an excess of standard indicators, experts can talk about the presence of the following dangerous pathologies:
- acute hepatitis;
- cirrhosis;
- hemolytic or congestive jaundice;
- acute rheumatic carditis;
- liver diseases, including cancer;
- acute pancreatitis and pulmonary artery thrombosis;
- cholestasis, myopathy;
- attacks of angina.
Also, increased concentrations of the cellular enzyme aspartate aminotransferase are most likely to be detected in cases of trauma, angiocardiography, or cardiac surgery. A reduced AST reading has no diagnostic value.
4.75 out of 5 (4 Votes)AST blood test is a biochemical blood test that determines the amount of intracellular enzyme aspartate aminotransferase.
This analysis method is used to diagnose diseases of the myocardium, liver and muscle disorders, and is usually prescribed simultaneously with ALT blood tests, as well as a bilirubin test.
This analysis allows you to determine the amount of cellular enzyme AST in the tissues of the liver, kidneys, heart, skeletal muscles, nervous system and other organs. If, during a blood test, the AST transcript shows a high amount of aspartate aminotransferase in the tissues of the body, this allows us to draw conclusions about the presence of disorders in a particular organ.
Norm
Normal AST content in the blood depends on the patient's gender:
- in women the figure is within 31 U/l;
- for men, the normal value is up to 41 U/l;
- in newborns, the norm is considered to be from 25 to 75 U/l;
- in children aged from one year to eighteen years – 15 to 60 U/l.
As you can see, the activity of aspartate aminotransferase in a woman’s body is slightly lower than in a man’s body, and in children it is higher than in adults.
Indications for the purpose of analysis
An AST blood test is necessary to accurately determine the intracellular enzyme aspartate aminotransferase, which is detected as a result of biochemical analysis.
It is prescribed in the following cases:
- All liver pathologies.
- All types of jaundice and bilirubin metabolism disorders.
- Autoimmune diseases.
- Endocrine diseases.
- Infections.
- Intoxication.
- Malignant tumors.
- Allergic skin diseases.
- Long-term treatment with antibiotics, chemotherapy and various toxic drugs.
- Diseases of the circulatory system.
- Chronic and acute heart diseases.
- Kidney failure.
- Injuries to the abdomen and chest.
- Preparation for a complex surgical operation.
- Purulent-septic pathologies.
- Encephalopathy of unknown etiology.
- Bile outflow disorders, cholelithiasis.
- Chronic pancreatitis.
- Evaluation of treatment of liver and cardiac pathologies
It is important to note that 7-15 days before donating blood for AST, you should completely avoid taking medications. However, if this cannot be done, the doctor should be informed of the amount of drugs and their daily dosage before drawing blood.
Causes of elevated AST
Why is the AST reading elevated and what does it mean? In adults, AST levels increase in diseases accompanied by the breakdown of tissues rich in these enzymes. An excess of AST by 2–5 times is considered moderate, 6–10 times is considered average, higher levels are considered a significant increase.
More often AST above normal is diagnosed when:
- or ;
- alcohol intoxication;
- development of obstructive jaundice;
- destruction of liver cells;
- dermatomyositis;
- mesenteric infarction;
- progressive muscular dystrophy;
- fatty liver;
- local radiation damage;
- acute;
- necrosis of cardiomyocytes (heart muscle cells);
- necrosis or injury of skeletal muscle cells;
- poisoning with chloroform, toadstool, carbon tetrachloride;
- therapy with hepatotoxic drugs and drugs that cause cholestasis.
Determination of AST levels is often carried out in combination with ALT. The presence of data on the level of these two enzymes allows us to assume the localization of the pathological process, its severity and make a prognosis. There is the so-called Ritis coefficient - the AST/ALT ratio. Normally, this indicator is 1.33. In case of heart disease it increases, and in case of liver pathology it decreases (with the exception of alcohol damage).
What to do
It is necessary to clearly understand that an increase in AST is not the cause of the disease. This is its consequence. Therefore, only the elimination of the causative disease can interrupt the cause-and-effect relationship, which will be reflected in the normalization of AST activity and will become a criterion for victory over this disease.
Any cases of increased aspartate aminotransferase are a reason to seek specialized medical help. This harmless and asymptomatic sign often hides severe chronic diseases, which will manifest themselves only after some time.
Since this sign signals the destruction of cells containing this enzyme (heart, liver, muscles), it is necessary to diagnose and treat diseases of these organs.
AST (aspartate aminotransferase) is one of the enzymes involved in the process of protein metabolism. In addition, it is responsible for the production of amino acids present in cell membranes.
AST is a specific enzyme and is not detected in all organs. The maximum amount of this type of aminotransferase is detected in the heart muscle, liver cells (hepatocytes), brain cells and muscle tissue. The reason is the significant speed of metabolic reactions.
The level of AST in the blood plasma remains within the acceptable range as long as the structure of the cells containing the enzyme remains normal. When the integrity of cell membranes is destroyed, AST is actively released into the systemic circulation.
When is a blood test for AST prescribed?
Blood biochemistry for AST, according to accepted diagnostic standards, is a mandatory test when many pathological conditions are suspected. This:
- heart disease occurring in chronic or acute form;
- diseases of the circulatory system;
- any abnormalities in liver function;
- poisoning or intoxication (alcohol or drugs) of the body;
- kidney disease, accompanied by the development of renal failure;
- purulent-septic reactions;
- various types of jaundice;
- deviations in the process of bilirubin metabolism;
- symptoms of ascites;
- signs of the development of portal hypertension;
- encephalopathy;
- diseases of autoimmune origin;
- acute abdominal conditions requiring surgical intervention;
- cholelithiasis;
- difficulties with the outflow of bile;
- chronic pancreatitis;
- pancreatic necrosis;
- diseases of the endocrine system;
- allergic reactions;
- malignant neoplasms with suspected spread of metastases;
- in case of injury to the chest and abdomen, as well as in case of suspected bruise of the liver and heart.
A blood test for AST is also prescribed:
- during long courses of chemotherapy, as well as during the period of taking antibiotics and other toxic drugs;
- as preoperative preparation;
- in order to assess the dynamics and effectiveness of prescribed drug therapy during the treatment of cardiac and renal pathologies.
How to prepare for the test
To perform the study, venous blood is taken. To get the most reliable results, it is necessary to carry out preparation. Doctors give specific recommendations.
- Since AST is an indicator of liver function, on the eve of blood donation it is necessary to exclude from the diet foods that load the organ. These are fatty, fried and spicy dishes/foods. Sauces, creams containing a significant percentage of fat, as well as “fast” food are prohibited. The increased fat content disrupts the course of protein metabolism, accelerating the blood clotting period.
- The AST blood test is performed on an empty stomach, i.e. on an empty stomach. The last time you are allowed to eat is 8 to 12 hours before visiting the laboratory.
- Drinking sugary drinks on the morning of blood donation is prohibited. Allowed only pure water no gases.
- Smoking is also prohibited on this day.
- Two to three days before the procedure, you need to completely eliminate alcohol-containing drinks from your diet. Even a small amount of alcohol taken on the eve of blood donation can completely change the clinical picture of the study.
- The diet on the eve of blood donation should not contain protein and dairy products - eggs, fatty cheeses, dairy and fermented milk products. Significant protein content distorts test results.
- On the eve of the day of visiting the laboratory, it is necessary to avoid significant physical activity, as this provokes an increase in many blood parameters. Before entering the office, it is advisable to sit for a short time and calm down.
- You should stop taking any medications whenever possible. You also need to inform the doctor about all the procedures that were performed on the eve of the test - radiography, fluorography, ultrasound examination, etc.
If a high AST score is diagnosed in the absence of pathological symptoms indicating an existing disease, a repeat blood test may be prescribed. The results of the analysis can be distorted by:
- taking sedatives of herbal origin, for example, valerian tincture;
- Taking echinacea also gives incorrect results;
- intake of significant doses of vitamin A into the human body;
- allergic attack;
- catheter installation;
- recent heart surgery.
Normal blood AST indicator
In a healthy person, when taking a biochemical blood test for AST, the minimum content of the enzyme is detected. The acceptable range of indicators depends on the age category and gender of the patient:
- In girls and women, the AST norm is 31-35 units/l. During the period of bearing a child, the level of the indicator remains normal. When it increases, there is a high probability of damage to liver and myocardial cells.
- For men, the permissible spread of AST is 41-50 units/l. The reason is increased enzyme activity.
- In a newborn baby, the AST level can rise to 70 units/l. The numbers will normalize later over the next few months.
- For children under one year of age, the normal level of AST in the blood is no more than 60 units/l. At the age of 1 year – 12 years – not higher than 45 units/l.
Advice! A decrease in AST levels is not of prognostic interest and is not a sign of the presence of any disease.
Elevated AST readings
An increase in the blood AST level is considered a deviation, but only if it is increased more than twice. In medicine, it is customary to distinguish several degrees of excess of the norm:
- moderate. With an increase of more than five times;
- average – up to ten times;
- heavy - ten times or more.
Detection of elevated blood AST levels may indicate the development of the following pathologies:
- myocardial infarction in the acute period. Tracking the dynamics of the indicator gives an idea of the extent of the process and the degree of recovery;
- heart injury, in particular bruise;
- myocarditis (regardless of the cause that caused it);
- viral hepatitis in acute or chronic form;
- toxic liver damage caused by taking poisons or medications;
- hepatosis of alcoholic origin;
- intoxications of an endogenous nature, provoked by infections or the development of a purulent-septic process of organs or soft tissues;
- chronic heart failure;
- cholestasis (stagnation of bile), provoked by the presence of a mechanical obstruction in the lumen of the bile duct - stones, neoplasia, congenital structural anomaly;
- impaired renal circulation;
- portal hypertension;
- cirrhotic liver damage with preservation of healthy areas;
- liver metastasis;
- neoplasia of the liver and bile ducts;
- damage to the heart and liver in myeloblastic leukemia;
- destruction of significant volumes of muscle tissue, in particular myodystrophy, myositis, etc.
The most common causes of increased blood AST are liver and heart problems:
- acute myocardial infarction. The growth of AST indicators increases until the formation of symptoms typical for the condition - pain, shortness of breath. If the doctor suspects the development of a heart attack, an AST test is performed several times in a row. An increase in indicators indicates the development of necrosis;
- hepatitis of viral origin. The disease is characterized by destruction of hepatocytes, which contributes to an increase in AST levels;
- cirrhosis and liver cancer. With the development of oncology and cirrhosis, destruction of liver cells also occurs and, as a result, the process releases a significant amount of AST;
- myocarditis. Destruction of the myocardium caused by the inflammatory process. It may be caused by an infection or an allergic response to a medication. In some cases, the nature of the disease remains unknown.
Possible complications
An increase in the blood AST level itself does not pose a danger to humans. Severe consequences can be caused by diseases and conditions that cause its increase. Frequent complications include:
- acute form of heart failure developing against the background of a passing myocardial infarction;
- hepatic coma. The condition can develop as a response of the body to the active destruction of hepatocytes. Typical for hepatitis of viral origin;
- myocardial rupture. The most complex and common complication of myocardial infarction. In the absence of medical care - urgent surgical treatment - there is a high probability of death;
- cardiac aneurysm. Another complication of myocardial infarction. It also requires surgical intervention, since the destruction of the aneurysm can occur at any time;
- liver cancer. The pathology most often develops against the background of chronic cirrhosis. The degeneration of organ cells that occurs can cause the formation of a malignant tumor.
Decreased AST levels
An increase in the blood AT level is only a symptom indicating the ongoing destruction of cells containing this enzyme (liver, muscle tissue and heart). For this reason, there are no drugs that reduce the rate.
As a rule, the patient is prescribed additional instrumental and laboratory research allowing for an accurate diagnosis. After this, drug therapy is selected. A decrease in AST will occur only after the disease is cured.
An increase in transaminase is a reason to contact your doctor to undergo a full medical examination. An increase in AST often occurs even before the onset of pathological symptoms, and therefore is an important diagnostic criterion. The interpretation of the results obtained should be carried out by a specialized specialist.
AST blood test (AST blood test) is a biochemical blood test that determines the amount of intracellular enzyme aspartate aminotransferase. This test method is used to diagnose diseases of the myocardium, liver and muscle disorders and is usually prescribed simultaneously with ALT blood tests and a bilirubin test.
The analysis allows you to detect the amount of cellular enzyme AST in the tissues of the liver, kidneys, heart, skeletal muscles, nervous system and other organs. If the transcript of the analysis shows a high amount of aspartate aminotransferase in the tissues of the body, this allows us to draw conclusions about the presence of disorders.
Indications for analysis
The AST blood test is prescribed for suspected myocardial infarction: it is one of the earliest markers that detect damage to the heart muscle. In addition, deciphering AST in a biochemical blood test allows for the diagnosis and monitoring of other diseases of the heart muscle, diseases of the hepatobiliary system and disorders of the skeletal muscles.
Preparing for analysis
The AST blood test is taken on an empty stomach. By the time of the study, at least eight hours must have passed since the last meal. The day before the blood sampling procedure, you should not eat fried or fatty foods or drink alcohol. It is also recommended to limit physical activity. Immediately after ultrasound, radiography, fluorography, rectal examination or physiotherapeutic procedures, blood is not donated for this analysis.
One to two weeks before the test, you must stop taking medications. If this is not possible, in the referral for examination the doctor must indicate what medications the patient is taking and in what doses.
The results of the study of AST activity can be affected by heavy physical activity performed shortly before taking a blood sample, alcohol consumption, hemolysis, chylosis in the sample (excess of fat microparticles in the blood) and taking a number of medications (opioids, methyldopa, chlorpropamide, sulfonamides, erythromycin, dicumarol , pyridoxine, anti-tuberculosis medications, as well as large doses of salicylates, acetaminophen, vitamin A).
Decoding
The normal AST blood test is:
for women - from 31 to 35 units/l.
For men - from 41 to 50 units/l.
In children under the age of one month - no more than 75 units/l,
from 2 to 12 months – no more than 60 units/l,
in children from one year to 14 years – less than 45 units/l.
Exceeding standard values may indicate cirrhosis, acute hepatitis, congestive or hemolytic jaundice, liver diseases, including cancer, acute attack of angina, acute rheumatic carditis, myopathy, cholestasis, pulmonary artery thrombosis and acute pancreatitis.
Also, an increased content of cellular enzyme in a biochemical blood test can be shown by deciphering AST in the case of injury, cardiac surgery or angiocardiography. A low AST reading has no diagnostic value.
An increase in AST activity in blood serum by 20 to 50 times often indicates liver diseases accompanied by necrotic processes and viral hepatitis. An increase in AST levels by 2 to 5 times may be evidence of hemolytic diseases, muscle injuries, acute pancreatitis, and gangrene. An increase in AST by 2–3 times may indicate pulmonary embolism. In muscular dystrophy and dermatomyositis, an eightfold increase in AST is often observed.