Why it matters: ALT and AST are key liver enzymes, and changes in their levels can indicate liver cell injury or other health ...

Liver enzymes are proteins in your liver that speed up chemical reactions. If your liver is damaged, blood tests will show abnormally high levels of these enzymes circulating in your bloodstream.

If you have high ALT levels — a liver enzyme known as alanine aminotransferase — it may be due to a liver problem. Here's what you need to know about these liver enzymes and how to lower your ALT ...