AST/GOT

What is being analysed?
AST is an enzyme found mainly in the heart and liver and, to a lesser extent, in muscles. When liver and muscle cells are damaged, they release AST into the blood.

How is it used?
When is it requested?
What does the test result mean?
Is there anything else I should know?

How is it used?
The AST test is generally used to assess liver damage.

AST levels are often compared with the levels of other enzymes, alkaline phosphatase (ALP) and alanine aminotransferase (ALT), to assess what type of liver disease is present.

Although AST is found in both the heart and muscles, another enzyme, creatine kinase (CK), is present in larger amounts and is used more often to assess heart or muscle damage.

When is it requested?
The AST test is requested together with many other tests to assess patients with symptoms of liver disease. Some of these symptoms include jaundice (yellow eyes and skin), dark urine, nausea, vomiting, abdominal swelling, unusual weight gain and abdominal pain. AST may be requested on its own or together with other tests for:

• people who have been exposed to hepatitis viruses,
• people who drink too much alcohol,
• people with a family history of liver disease, or
• people taking medicines that can occasionally damage the liver.

People with mild symptoms, such as tiredness, may have an AST test to make sure they do not have chronic liver disease. AST is often used to assess the treatment of people with liver disease and may be requested on its own or with other tests.

What does the test result mean?
Very high AST levels (more than 10 times the upper reference limit) are usually due to acute hepatitis, often caused by a viral infection. In acute hepatitis AST levels stay high for 1-2 months, but can take 3 to 6 months to return to normal. In chronic hepatitis AST levels are not as high, often no more than 4 times the upper reference limit. In chronic hepatitis AST levels range from normal to moderately raised, which is why the doctor will often repeat the test to follow the trend.

In some liver diseases, especially when the bile ducts are blocked, or in cirrhosis or some types of liver cancer, AST may be close to normal, but it is raised more often than ALT. When liver damage is due to alcohol, AST often rises much more than ALT (a pattern seen in only a few other liver diseases). AST is also raised after a heart attack and with muscle damage, usually much more than ALT.

Is there anything else I should know?
Pregnancy can lower AST levels. An intramuscular injection or very intense exercise can raise AST levels. In rare cases some medicines can damage the liver or muscle, raising AST. This can be true both of prescribed medicines and of some “natural” products. If high AST levels are found, it is very important to tell your doctor about all the medicines or products you are taking.

1. What is hepatitis?
2. What other tests are used to assess liver disorders?
3. Who is at risk of liver disease?
4. What signs should make me suspect liver disease?

1. What is hepatitis?
Hepatitis is inflammation of the liver. There are two main categories: acute and chronic. Acute hepatitis causes noticeable flu-like symptoms, often with loss of appetite, diarrhoea and vomiting. In some cases of hepatitis the urine may turn brown, the stools pale and the skin and eyes yellow. Most affected people recover completely. Chronic hepatitis usually causes no symptoms, or a lack of energy and tiredness; many people do not know they have it. In some people chronic hepatitis can gradually damage the liver and, after many years, lead to liver failure.

2. What other tests are used to assess liver disorders?
Other tests commonly used to assess liver disease include other enzymes found in liver cells, such as alanine aminotransferase (ALT) and alkaline phosphatase (ALP), and bilirubin (a yellow pigment in the blood that is removed by the liver).

3. Who is at risk of liver disease?
While many things can damage the liver, the main causes of liver damage are infections with viruses that target the liver, and alcohol abuse. In rare cases some medicines can damage the liver; your doctor may suggest occasional liver tests if you are taking one of these medicines. Some diseases inherited from parents can occasionally damage the liver.

4. What signs should make me suspect liver disease?
In many cases liver disease causes no symptoms. When the liver is damaged quickly (a condition called acute hepatitis), the skin and the whites of the eyes turn yellow, the urine turns brown and the stools lose their colour. In advanced stages, liver disease can cause abdominal swelling, vomiting blood, confusion and easy bruising