At a Glance
Why Get Tested?
To screen for liver disease
When to Get Tested?
If your doctor thinks that you have symptoms of a liver disorder
A blood sample taken from a vein in your arm
Test Preparation Needed?
No test preparation is needed, although you should inform your doctor about any drugs you are taking
The Test Sample
What is being tested?
ALT is an enzyme found mostly in the liver; smaller amounts are also found in the kidneys, heart, and muscles. When the liver is damaged, ALT is released into the bloodstream, hence increasing the concentration that can be detected in a blood test. This often happens before more obvious symptoms of liver damage occur, such as jaundice (yellowing of the eyes and skin).
How is the sample collected for testing?
A blood sample will be taken 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, although you should inform your doctor about any drugs you are taking.
Ask a Laboratory Scientist
NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.