Enzymes are proteins found in your body that speed up certain chemical reactions. Liver enzymes perform these jobs within the liver. Two of the common ones are known as "AST" and "ALT."

If the liver is damaged, AST and ALT pass into the bloodstream. When your provider looks at the results from your blood tests, AST and ALT values are higher than normal if your liver is damaged.

The damage to the liver can come from viruses, such as the hepatitis C virus, over-the-counter drugs, and prescription and street drugs. If your provider starts you on a certain medication, they may need to monitor your blood chemistries to make sure the medication is not causing further harm to your liver.

Scroll over image to see an animation of liver enzymes leaking into the blood.

Results of liver enzyme tests

Low level of liver enzymes in blood:

Usually, this means the liver is healthy. However, a patient may have normal liver enzymes levels but still have liver damage.

Higher than normal level of liver enzymes in blood:

This can mean the liver is unhealthy. Patients also can have higher than normal liver enzyme levels related to problems in other organs, such as their bile ducts.