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AST (Aspartate Aminotransferase)
Test Code822
CPT Codes
84450
Preferred Specimen
1 mL serum
Minimum Volume
0.5 mL
Other Acceptable Specimens
Plasma collected in a sodium heparin (green-top) or lithium heparin (green-top) tube
Instructions
Centrifuge serum or plasma specimens within 1 hour of collection, transfer serum or plasma to a sterile, plastic, screw-capped vial(s), and ship at room temperature
Transport Temperature
Room temperature
Specimen Stability
Serum and plasma
Room temperature: 4 days
Refrigerated: 7 days
Frozen: 5 days
Room temperature: 4 days
Refrigerated: 7 days
Frozen: 5 days
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Hemolysis • Anticoagulants other than heparin
Methodology
Spectrophotometry (SP)
Setup Schedule
Set up: Mon, Wed, Fri; Report available: 3-6 days
Clinical Significance
AST is widely distributed throughout the tissues with significant amounts being in the heart and liver. Lesser amounts are found in skeletal muscles, kidneys, pancreas, spleen, lungs, and brain. Injury to these tissues results in the release of the AST enzyme to general circulation. In myocardial infarction, serum AST may begin to rise within 6-8 hours after onset, peak within two days and return to normal by the fourth or fifth day post infarction. An increase in serum AST is also found with hepatitis, liver necrosis, cirrhosis, and liver metastasis.
