AST stands for aspartate aminotransferase. This enzyme is found primarily in the liver, as well as the kidneys, cardiac and skeletal muscle. According to the FamilyPracticeNotebook.com, AST is also called serum glutamic oxaloacetic transaminase or glutamic oxaloacetic transaminase. It is one of a family of liver enzymes.
Related Enzymes
AST is usually found on lab reports along with a small handful of other liver enzymes such as alanine aminotransferance, alkaline phosphatase, and gamma-glutamyl transferase. These other enzymes are abbreviated ALT, AP, and GGT respectively. Taken together, they provide a snapshot of liver function.
Significance
According to MedlinePlus, AST and other liver enzymes such as ALT and ALP are used to monitor liver diseases such as cirrhosis, hepatitis, liver cancer and infectious mononucleosis. High levels are also consistent with conditions such as a lack of blood flow to the liver, liver necrosis and the use of drugs that are toxic to the liver.
In the absence of other indicators, high levels of AST can suggest other non-hepatic diseases such as hemolytic anemia, acute pancreatitis, various cardiac issues and even recent surgery.
Normal Values
MedlinePlus reports that the range of normal levels of AST is between is 10 to 34 international units per liter. According to FamilyPracticeNotebook.com, values less than 35 are considered normal. The GP Notebook indicates that normal values for men may be slightly higher than values for women.
Generally, doctors look for values that are too high rather than too low.
Other Uses
AST values are often reported as a ratio with another liver enzyme called alanine aminotransferase or ALT. According to FamilyPracticeNotebook.com, doctors suspect alcoholism if the ratio of AST tp ALT is greater than 2. If ratio exceeds four, doctors may suspect Wilson's Disease.
Limitations
Taken alone, AST is not a good diagnostic indicator for liver disease because the small amounts of this enzyme found in areas other than the liver may contribute to the amount that is presumed to come from the liver. For this reason, doctors usually measure a whole panel of liver enzymes.
