Does this test have other names?

Alanine aminotransferase, serum glutamic-pyruvic transaminase, SGPT

What is this test?

This test measures the amount of the enzyme alanine aminotransferase (ALT) in your blood.

ALT, formerly called SGPT, is mostly found in your liver cells. When liver cells are injured, they release this enzyme into your blood. High levels are a sign of liver damage.

This test is part of a group of tests commonly referred to as "liver function tests." The results of these tests give health care providers an overall picture of how well your liver is working.

Why do I need this test?

You may have this test to see if you have liver damage or a liver disease, such as hepatitis. Symptoms of liver diseases include:

• Extreme tiredness or weakness.

• Loss of appetite.

• Yellowing of the eyes and skin (jaundice).

• Dark yellow urine or light-colored stool.

• Belly (abdominal) pain.

• Nausea and vomiting.

• Diarrhea.

• Headache.

You may also have this test to look for cirrhosis, which causes damage and scarring to the liver. Causes of cirrhosis include long-term hepatitis infection, excessive alcohol use, obesity, and exposure to certain medicines or toxins. Symptoms of cirrhosis include:

• Abdominal swelling from fluid buildup.

• Visible blood vessels in the skin.

• Itchy skin.

• Swelling of the legs, feet, or ankles.

• Nausea, loss of appetite.

• Weight loss.

• Feeling tired (fatigue).

What other tests might I have along with this test?

Your health care provider may also order other tests of liver health, including:

• Albumin.

• Bilirubin.

• Alkaline phosphatase (ALP).

• Aspartate aminotransferase (AST).

• Prothrombin time (PT).

Your provider may also order other tests that measure:

• Your liver's ability to process substances from your blood.

• Levels of substances your liver produces.

• Liver inflammation.

What do my test results mean?

Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your health care provider.

ALT levels are normally less than 40 international units per liter (IU/L). Levels above 1,000 IU/L may be a sign of:

• Acute viral hepatitis.

• Lack of blood flow to the liver.

• Injuries from illegal drugs or toxins.

The ratio of AST to ALT may also provide helpful information to your provider. AST levels are normally lower than ALT levels. AST is often higher than ALT in cases such as:

• Hepatitis from alcohol use.

• Cirrhosis in people with long-term viral hepatitis.

A number of other medical conditions besides liver disease can also cause liver enzymes to rise. These include:

• Muscle diseases.

• Celiac disease.

• Thyroid problems.

• Gallstones.

• Adrenal gland problems.

How is this test done?

The test requires a blood sample, which is taken through a needle from a vein in your arm.

Does this test pose any risks?

Taking a blood sample with a needle carries risks that include bleeding, infection, bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight stinging sensation or pain. Afterward, the site may be slightly sore.

What might affect my test results?

Many medicines can affect your test results, as can drinking alcohol. ALT levels may also be higher in people who are obese.

How do I get ready for this test?

Your health care provider may ask you to not eat or drink and to not take certain medicines before your blood tests. Be sure your provider knows about all the medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illegal drugs you may use.