Aspartate Amino Transferase (AST)

CPT Code: 84450
Order Code: C113
ABN Requirement:  No
Synonyms: AST; Serum Glutamic Oxaloacetic Transaminase; SGOT
Specimen: Serum
Volume: 0.5 mL
Minimum Volume: 0.2 mL
Container: Gel-barrier tube (SST, Tiger Top)

Collection:

  1. Collect and label sample according to standard protocols.
  2. Gently invert tube 5 times immediately after draw. DO NOT SHAKE.
  3. Allow blood to clot 30 minutes.
  4. Centrifuge for 10 minutes.

Transport: Store serum at 2°C to 8°C after collection and ship the same day per packaging instructions included with the provided shipping box.

Stability:

Ambient (15-25°C): Not Acceptable
Refrigerated (2-8°C): 7 days
Frozen (-20°C): not acceptable

Causes for Rejection: Specimens other than serum; improper labeling; samples not stored properly; samples older than stability limits; hemolyzed specimens

Methodology: Photometric

Turn Around Time: 1 to 3 days

Reference Range:

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.

Limitations: Sample contamination with erythrocytes will elevate results because the AST level in erythrocytes is higher than in normal sera. Isoniazid can cause artificially low, and Furosemide artificially high, ALT results at therapeutic concentrations. In very rare cases gammopathy may cause unreliable results. Lipemia may cause unreliable results.

The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.