Liver enzymes

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 doctor 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 VA doctor starts you on a certain medication, he or she 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 liver enzymes leaking into the blood.