When to Worry about ALT Levels? Alanine Transaminase (ALT) Test

Alanine transaminase or ALT is one of those tests your doctor will order you if you need to rule out liver disease. There are different types of liver function tests, and ALT, along with AST, are two of the most important and commonly used. They are both excellent tools to evaluate liver damage.

But what is alanine transaminase? When is it ordered, and why is it useful? We’ll address these and other questions in this article.

What is Alanine Transaminase (ALT)?

Alanine transaminase is also known as alanine aminotransferase. It is an enzyme produced in the liver and other parts of the body such as the kidneys and to a certain degree in the skeletal muscle and the heart. There should not be many ALT enzymes in the blood because this enzyme does basically nothing there. Its primary function is inside the cell. But the enzyme can be found in high levels in the blood when there’s liver damage, and hepatocytes break, releasing enzymes in the general circulation.

As such, Alanine transaminases or ALT is a marker of liver damage or liver disease. It is an indirect marker because its levels depend on the destruction of liver cells, the release of the enzyme into the general circulation, and the clearance of these enzymes from the blood.