ALT

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." Results of these tests give doctors 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 a liver disease, such as hepatitis. Symptoms of liver diseases include:

• Extreme tiredness

• Yellowing of the eyes and skin, a condition called jaundice

• Abdominal (belly) 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 medications or toxins. Symptoms of cirrhosis include:

• Abdominal swelling from fluid buildup

• Visible blood vessels in the skin

• Itchy skin

What other tests might I have along with this test?

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

• Albumin

• Bilirubin

• Alkaline phosphatase,  or  ALP

• Aspartate aminotransferase, or AST

• Prothrombin time, or  PT

Your doctor 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 drugs or toxins

The ratio of AST to ALT may also provide helpful information to your health care 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

• Adrenal gland problems

How is this test done?

The test requires a blood sample, which is drawn 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 medications can affect your test results, as can drinking alcohol.

How do I get ready for this test?

You don't need to prepare for this test. But be sure your doctor knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illicit drugs you may use.