What are the normal ranges for AST and ALT tests? What do high or low results mean? Explore the causes and symptoms of abnormal AST and ALT levels, and learn how these liver enzyme tests can help diagnose various health conditions.

Understanding AST (Aspartate Aminotransferase) Blood Test

Aspartate aminotransferase (AST) is an enzyme found predominantly in the liver, but also in other organs like the heart, muscles, and kidneys. When cells containing AST are damaged, they release the enzyme into the bloodstream. An AST blood test measures the amount of this enzyme present in the blood, which can help diagnose and monitor liver diseases or other health conditions.

Why Are AST and ALT Tests Ordered?

AST tests are often ordered as part of a routine checkup or liver function panel to assess the health of the liver. They may be used to help diagnose or monitor conditions like hepatitis, cirrhosis, mononucleosis, or other liver diseases. AST tests may also be ordered if a person has symptoms of liver damage, such as nausea, fatigue, jaundice, or abdominal pain.

AST tests are often ordered along with alanine aminotransferase (ALT) tests, as these two liver enzymes can provide valuable insight into liver function. Elevated levels of both AST and ALT may indicate liver damage or disease.

What Are Normal AST Levels?

The normal range for AST levels in the blood is:
– Men: 8 to 48 units per liter (U/L)
– Women: 6 to 41 U/L

It’s important to note that normal ranges can vary slightly between different labs and may also depend on factors like age and gender. If your AST levels are outside the normal range, it doesn’t necessarily mean you have a medical condition. Your healthcare provider will interpret the results in the context of your overall health and any other symptoms you may be experiencing.

What Causes High AST Levels?

There are several potential causes of elevated AST levels, including:
– Liver disease (e.g. hepatitis, cirrhosis, fatty liver disease)
– Heart disease (e.g. heart attack, myocarditis)
– Muscle damage (e.g. from vigorous exercise, injury, or certain medications)
– Pancreatitis
– Certain medications (e.g. acetaminophen, statins, antidepressants)
– Alcohol abuse
– Diabetes
– Hypothyroidism

High AST levels are often seen in liver diseases, as the damaged liver cells release more of the enzyme into the bloodstream. However, elevated AST can also occur with conditions affecting other organs, so your healthcare provider will need to consider your medical history and any other symptoms to determine the underlying cause.

What Causes Low AST Levels?

Low AST levels are less common and may be caused by:
– Vitamin B6 deficiency
– Malnutrition
– Severe liver disease (in the late stages when liver cells have been severely damaged)
– Chronic alcohol use

In most cases, low AST levels are not a cause for concern on their own and may simply reflect normal variation. However, if you have consistently low AST levels and other concerning symptoms, it’s important to discuss this with your healthcare provider.

Interpreting AST and ALT Test Results

When interpreting AST and ALT test results, healthcare providers will look at the levels of both enzymes, as well as the ratio between them. Generally, a higher AST than ALT level (AST/ALT ratio greater than 1) may indicate liver damage from causes like alcohol abuse or cirrhosis. A higher ALT than AST level (AST/ALT ratio less than 1) is more commonly seen with viral hepatitis or fatty liver disease.

The specific interpretation of AST and ALT results will depend on the individual patient’s medical history, symptoms, and other laboratory tests. Your healthcare provider can help you understand what your results mean and whether further testing or treatment is needed.

Frequently Asked Questions

What are the symptoms of high AST levels?

Symptoms of high AST levels may include nausea, vomiting, fatigue, weakness, jaundice, abdominal pain, and dark-colored urine. However, some people with elevated AST may not have any noticeable symptoms.

Can exercise cause high AST levels?

Yes, strenuous or prolonged exercise can cause a temporary increase in AST levels, as the enzyme is released from damaged muscle cells. This is usually not a cause for concern in otherwise healthy individuals.

Do AST levels indicate liver cancer?

Elevated AST levels can sometimes be a sign of liver cancer, but they are not a definitive indicator. AST tests are more commonly used to detect general liver damage or disease. Additional testing, such as imaging studies or a liver biopsy, would be required to diagnose liver cancer.

How long does it take for AST levels to return to normal?

The time it takes for AST levels to return to the normal range can vary depending on the underlying cause. In cases of acute liver injury or muscle damage, AST levels may return to normal within a few days to weeks once the issue has resolved. For chronic liver diseases, it may take longer for AST levels to normalize.

AST Test: MedlinePlus Medical Test

What is an AST Test?

AST (aspartate aminotransferase) is an enzyme that is found mostly in the liver, but it’s also in muscles and other organs in your body. When cells that contain AST are damaged, they release the AST into your blood. An AST blood test measures the amount of AST in your blood. The test is commonly used to help diagnose liver damage or disease.

Other names: SGOT test, serum glutamic oxaloacetic transaminase test; aspartate transaminase test

What is it used for?

An AST blood test is often part of a routine blood screening to check the health of your liver. The test may help diagnose or monitor liver problems. It may also help diagnose other health conditions.

Why do I need an AST blood test?

You may get an AST blood test as part of your routine checkup or if you have symptoms of liver damage. These may include:

• Nausea and vomiting
• Lack of appetite
• Fatigue
• Weakness
• Jaundice, a condition that causes your skin and eyes to turn yellow
• Swelling and/or pain in your abdomen (belly)
• Swelling in your ankles and legs
• Dark-colored urine (pee) and/or light-colored stool (poop)
• Frequent itching

Even if you don’t have symptoms, your health care provider may order an AST blood test if you’re more likely to develop liver disease because of:

• A family history of liver disease
• Alcohol use disorder
• Obesity
• Diabetes
• Taking certain medicines that can cause liver damage
• Hepatitis or exposure to hepatitis

What happens during an AST blood test?

A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.

Will I need to do anything to prepare for the test?

You don’t need any special preparations for an AST blood test. But an AST test is usually ordered with other blood tests. You usually need to fast (not eat or drink) for up to 12 hours before these tests. Your provider will let you know if there are any special instructions to follow.

Are there any risks to the test?

There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

What do the results mean?

High levels of AST in the blood may be a sign of hepatitis, cirrhosis, mononucleosis, or other liver diseases. High AST levels may also be a sign of heart problems or pancreatitis.

If your results are not in the normal range, it doesn’t always mean that you have a medical condition that needs treatment. Many things can affect your results, such as certain medicines and your age, sex, and diet. To learn what your results mean, talk with your provider.

Learn more about laboratory tests, reference ranges, and understanding results.

Is there anything else I need to know about an AST blood test?

Your health care provider may order an ALT blood test with your AST blood test. ALT stands for alanine transaminase, which is another type of liver enzyme. If you have high levels of AST and/or ALT, it may mean that you have some type of liver damage.

You may also have an AST test as part of a group of liver function tests that measure ALT, and other enzymes, proteins, and substances in the liver.

References

1. American Liver Foundation. [Internet]. New York: American Liver Foundation; c2017. Diagnosing Liver Disease – Liver Biopsy and Liver Function Tests; [updated 2020 Feb 17; cited 2022 Feb 14]; [about 3 screens]. Available from: https://liverfoundation. org/for-patients/about-the-liver/diagnosing-liver-disease/
2. Hinkle J, Cheever K. Brunner & Suddarth’s Handbook of Laboratory and Diagnostic Tests. 2nd Ed, Kindle. Philadelphia: Wolters Kluwer Health, Lippincott Williams & Wilkins; c2014. Aspartate Aminotransferase; p. 68–69.
3. National Heart, Lung, and Blood Institute [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; Blood Tests; [cited 2022 Feb 14]; [about 15 screens]. Available from: https://www.nhlbi.nih.gov/health-topics/blood-tests
4. Testing.com [Internet]. Seattle (WA).: OneCare Media; c2022. Aspartate Aminotransferase: The Test; [modified 2021 Nov 9; cited 2022 Feb 14; [about 14 screens]. Available from: https://www.testing.com/test/aspartate-aminotransferase-ast/
5. University of Rochester Medical Center [Internet]. Rochester (NY): University of Rochester Medical Center; c2017. Health Encyclopedia: Aspartate Transaminase; [cited 2017 Mar 13]; [about 2 screens]. Available from: https://www. urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=167&contentid=aspartate_transaminase

Aspartate aminotransferase (AST) blood test

Medical Tests 

Definition

The aspartate aminotransferase (AST) blood test measures the level of the enzyme AST in the blood.

Alternative Names

Aspartate aminotransferase; Serum glutamic-oxaloacetic transaminase; SGOT

How the Test is Performed

A blood sample is needed.

How to Prepare for the Test

No special preparation is needed.

How the Test will Feel

When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon goes away.

Why the Test is Performed

AST is an enzyme found in high levels in the liver, heart, and muscles. It is also found in lesser amounts in other tissues. An enzyme is a protein that causes a specific chemical change in the body.

Injury to the liver results in release of AST into the blood.

This test is mainly done along with other tests (such as ALT, ALP, and bilirubin) to diagnose and monitor liver disease.

Normal Results

The normal range is 8 to 33 U/L.

Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or may test different samples. Talk to your health care provider about the meaning of your specific test results.

What Abnormal Results Mean

An increased AST level is often a sign of liver disease. Liver disease is even more likely when the levels of substances checked by other liver blood tests have also increased.

An increased AST level may be due to any of the following:

adam.com”>
• Scarring of the liver (cirrhosis)
• Death of liver tissue
• Heart attack
• Too much iron in the body (hemochromatosis)
• Swollen and inflamed liver (hepatitis)
• Lack of blood flow to the liver (liver ischemia)
• Liver cancer or tumor
• Use of drugs that are toxic to the liver, especially alcohol use
• Mononucleosis (“mono”)
• Muscle disease or trauma
• Swollen and inflamed pancreas (pancreatitis)

AST level may also increase after:

• Burns (deep)
• Heart procedures
• Seizure
• Surgery

Pregnancy and exercise may also cause an increased AST level.

Risks

There is little risk involved with having your blood taken. Veins vary in size from one person to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.

Risks associated with having blood drawn are slight, but may include:

• Fainting or feeling lightheaded
• Excessive bleeding
• Multiple punctures to locate veins
• Hematoma (blood collecting under the skin)
• Infection (a slight risk any time the skin is broken)

References

Chernecky CC, Berger BJ. Aspartate aminotransferase (AST, aspartate transaminase, SGOT) – serum. In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures. 6th ed. St Louis, MO: Elsevier Saunders; 2013:172-173.

Pincus MR, Tierno PM, Gleeson E, Bowne WB, Bluth MH. Evaluation of liver function. In: McPherson RA, Pincus MR, eds. Henry’s Clinical Diagnosis and Management by Laboratory Methods. 23rd ed. St Louis, MO: Elsevier; 2017:chap 21.

Pratt DS. Liver chemistry and function tests. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran’s Gastrointestinal and Liver Disease. 10th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 73.

Review Date: 01/26/2019

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only — they do not constitute endorsements of those other sites. Copyright ©2019 A.D.A.M., Inc., as modified by University of California San Francisco. Any duplication or distribution of the information contained herein is strictly prohibited.

Information developed by A.D.A.M., Inc. regarding tests and test results may not directly correspond with information provided by UCSF Health. Please discuss with your doctor any questions or concerns you may have.

ALT and AST (blood chemistry)

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

ALT and AST – these abbreviations can often be seen in a blood test for biochemistry. What do they mean? What can they tell the doctor? Vasilisa Vladimirovna Ishchenko, a gastroenterologist at Clinic Expert 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 negligible. The highest concentration of ALT is observed 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, heart muscle, skeletal muscles, and pancreas.

AST, or aspartate aminotransferase, is also an enzyme from the group of transaminases that is involved in amino acid metabolism. It is found mainly in the liver, myocardium, nervous tissue, skeletal muscles, and to a lesser extent 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 a violation of the permeability of cell membranes, components of the cytoplasm and decayed intracellular structures, including enzymes, enter the blood serum. As a result, the level of ALT and AST in the blood rises. This complex of disorders is called the 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 the physiological destruction of aged cells (apoptosis). Deviation from the norm of the level of ALT and AST and a change in their ratio is 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 in dynamics.

— When are these tests recommended?

– Data on the level of ALT and AST may be important for such non-specific symptoms as general weakness, decreased performance, lack of appetite, nausea, vomiting, abdominal pain, flatulence, yellowing of the skin and mucous membranes. These indicators are necessarily determined for the diagnosis of diseases and the assessment of the functioning of the liver.

Read related materials:

Not always gastroscopy. Examination for pain in the abdomen
Insidious pain-mask. Does abdominal pain always indicate problems with the gastrointestinal tract?
Mom, my stomach hurts! What is hidden behind the pain in the abdomen in a child?
How not to become a balloon? Getting rid of gas formation in the intestines
Why do people turn yellow?

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

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

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

Read related materials:

How to protect yourself from Botkin’s disease?
Shield and sword from hepatitis C. How to protect yourself and your loved ones?
“Silent killer” of contemporaries
Invisible disease: fatty liver disease
What can you catch on vacation? Beware of malaria!
Polio is back?
How to prevent myocardial infarction?

— What can cause a decrease in ALT and AST levels in the blood?

– Vitamin B6 deficiency, severe liver cirrhosis, pancreatic pathologies, renal failure (especially in patients on hemodialysis).

— How does the level of ALT and AST in the blood during pregnancy change?

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

— Vasilisa Vladimirovna, do you need to prepare for the test for ALT and AST? If so, which one?

– Definitely required. Blood from a vein must be taken in the morning on an empty stomach (the last meal 12 hours before the study). On the eve of the test, severe physical exertion, changes in diet, and the use of alcoholic beverages should be avoided. Half an hour before blood sampling, you should also refrain from smoking.

I want to emphasize that the determination of only the level of ALT and AST is not always informative enough, therefore, most often doctors prescribe them in combination with other biochemical indicators.

Would you like to read about other tests? You can find articles about them in our section on laboratory diagnostics

You can sign up and take tests here
ATTENTION: the service is not available in all cities

Interviewed by Sevil Ibraimova

Editorial recommends:

Blood biochemistry: frequently asked questions
Liver reboot. What will we clean?
Delete or keep? What to do if gallstones are found?

For information:

Ishchenko Vasilisa Vladimirovna

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

In 2016 she completed her internship in Therapy and underwent retraining in gastroenterology.

Currently holds the position of a gastroenterologist at the “Expert Clinic” Kursk. Conducts reception at the address: st. Karl Liebknecht, 7.

ALT and AST what is it?

ALT ( alanine aminotransferase) and AST (aspartate aminotransferase) – belong to aminotransferase enzymes involved in amino acid metabolism. They are also called liver enzymes. They are found mainly in the cells of the liver and in other organs: pancreas, heart, kidneys, muscle tissue. A small amount of ALT and AST may appear in the blood due to physiological processes. However, in case of liver diseases (infectious or toxic hepatitis, tumor), damage to the liver cells occurs, the permeability of cell membranes is impaired and a large amount of ALT and AST enzymes are released into the blood – as a result, a cytolytic syndrome develops.

ALT and AST transaminases are specific markers of liver disease. Indications for their appointment may be the following:

• Presence of symptoms: nausea, vomiting, abdominal pain, yellowing of the skin and sclera, lethargy.
• laboratory diagnostics of liver diseases: viral hepatitis A, B, C, toxic hepatitis, fatty non-alcoholic liver disease (steatohepatitis), alcoholic liver disease, cirrhosis of the liver.
• Monitoring the dynamics of therapy for liver diseases.

Norms for the content of liver enzymes in the blood:

Age	Men	Women	Units
0-1 years	13-45		U/ml
1-60 years old	10-40	7. 0-35.0
60-90 years old	13.0-40.0	10.0-28.0
Over 90 years old	6.0-38	5.0-24.0

Reasons for increasing ALT, AST (hepatic and extrahepatic)

The level of ALT in acute viral or drug-induced hepatitis can rise 50 times or more. With steatohepatitis and alcoholic liver disease, the increase in ALT is moderate – no more than 5 times. In chronic hepatitis, there is an increase in ALT by about 7 times. In cirrhosis, ALT and AST values ​​increase by 3-5 times, while AST may be higher than ALT.

During pregnancy, a woman’s body experiences an increased load, so there may be a slight increase in transaminases.

Currently, macro-AST-emia syndrome has become known – this is a rare condition in which complexes are formed in the human body from the AST molecule and immunoglobulin. This condition may be hereditary or associated with liver disease. It is characterized by a prolonged and asymptomatic increase in alanine aminotransferase in the blood.

An important diagnostic value is not only an increase in the level of transaminases, but also a decrease. A decrease in ALT and AST below normal indicates end-stage cirrhosis or severe liver damage in hepatitis. This is an extremely unfavorable sign, as it indicates the total destruction of liver cells.