ALT

Also known as: Serum glutamic-pyruvic transaminase; SGPT; Alanine transaminase; AST/ALT ratio

Formal name: Alanine aminotransferase

Related tests: AST; ALP; GGT; Bilirubin; Liver panel; Albumin; Total Protein

The Test Sample

What is being tested?

Alanine aminotransferase (ALT) is an enzyme found mostly in the cells of the liver and kidney; much smaller amounts of it are also found in the heart and muscles. In healthy individuals, ALT levels in the blood are low. When the liver is damaged, ALT is released into the blood stream, usually before more obvious symptoms of liver damage occur, such as jaundice. This makes ALT a useful test for detecting liver damage.

The liver is a vital organ located in the upper right-hand side of the abdominal area. It is involved in many important functions in the body. The liver helps to process the body's nutrients, manufactures bile to help digest fats, produces many important proteins such as blood clotting factors, and breaks down potentially toxic substances into harmless ones that the body can use or excrete.

A number of conditions can cause damage to liver cells, resulting in an increase in ALT levels. The test is most useful in detecting damage due to hepatitis and drugs or other substances toxic to the liver. ALT, however, is not entirely specific for the liver, and mild to moderately increased levels may also be seen in conditions affecting other parts of the body.

How is the sample collected for testing?

A blood sample is drawn from a vein in the arm.

NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.

Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.