Aspartate Aminotransferase (AST)

Test Code

38439

CPT Codes
84450<br>Limited Access Code

Preferred Specimen

1 mL plasma collected in a plasma separator tube

Minimum Volume

0.5 mL

Instructions

Centrifuge plasma specimens within 1 hour of collection, transfer plasma to a sterile, plastic screw-capped vial(s), ship at room temperature.

Transport Container

Sterile, plastic screw-cap vial

Transport Temperature

Room temperature

Specimen Stability

Room temperature: 4 days
Refrigerated: 7 days
Frozen: 5 days

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Unspun plasma separator tube; Unspun green-top tube (heparinized plasma not separated from cells); Anticoagulants other than lithium heparin, sodium heparin or fluoride/oxalate; hemolysis; Anticoagulants other than heparin

Methodology
Spectrophotometry

Setup Schedule

Set up: Daily; Report available: 1-2 days

Reference Range

Male:
<1 month: 3-51 U/L
1-11 months: 3-65 U/L
1-3 years: 3-56 U/L
4-6 years: 20-39 U/L
7-19 years: 12-32 U/L
20-49 years: 10-40 U/L
> or = 50 years: 10-35 U/L

Female:
<1 month: 3-49 U/L
1-11 months: 3-79 U/L
1-3 years: 3-69 U/L
4-6 years: 20-39 U/L
7-19 years: 12-32 U/L
20-44 years: 10-30 U/L
> or = 45 years: 10-35 U/L

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.

The CPT Codes provided in this document 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 payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.