AST
What it measures, and what changes the number.
AST (aspartate aminotransferase) is an enzyme found in the liver but also in heart and skeletal muscle, kidneys and red blood cells. When these cells are damaged the enzyme is released into the blood, and the test measures its activity in serum or plasma.
It is usually read with ALT, since ALT is more concentrated in the liver and comparing the two helps separate liver from other sources. ALP, GGT and bilirubin complete the liver panel, and CK is often added when muscle is a possible source.
Because red blood cells contain AST, a hemolyzed sample (where cells broke during collection or handling) can raise the reading. Intense exercise in the preceding days can also increase it through muscle release. Assay methods with or without a vitamin cofactor can give slightly different results. Older reports call it GOT, and Spanish-language reports may print Aspartato aminotransferasa (AST/GOT).
Often read alongside: ALT, GGT, ALP, CK, Bilirubin (total)