AST levels increase when there's damage to the tissues and cells where the enzyme is found. AST levels can rise as soon as six hours after damage to tissue occurs. The normal range for AST is higher from birth to age 3 compared to the normal ranges for older children and adults.

What causes high AST and ALT levels?

Chronic alcohol consumption, drugs, non-alcoholic steatohepatitis (NASH) and chronic viral hepatitis are common causes associated with raised ALT and AST. In chronic viral hepatitis, the elevation of liver enzyme may not correlate well with the degree of liver damage.

What is considered a high AST level?

Typically the range for normal AST is reported between 10 to 40 units per liter and ALT between 7 to 56 units per liter. Mild elevations are generally considered to be 2-3 times higher than the normal range. In some conditions, these enzymes can be severely elevated, in the 1000s range.