Aspartate Aminotransferase (AST/SGOT)

 

CPT Code: 84450
Specimen: Serum or Plasma
Volume: 1 mL
Minimum Volume: 0.5 mL
Container: Red-top tube, gel-barrier tube, green-top (heparin) tube, or lavender-top (EDTA) tube
Methodology: Kinetic
Collection: Separate serum or plasma from cells within 45 minutes of collection.  Complete clot formation should take place before centrifugation.
Reference Range: 15-37 IU/L

Stability: 

Temperatures   Period 
Room Temperature (20-25 ⁰C) 3 Days
Refrigerated (2-8 ⁰C) 7 Days
 Frozen  (≤ -20 ⁰C) 1 Month

 

Use: This enzyme is found primarily in the heart, liver, and muscle. Any damage, trauma, or disease involving any of these tissues can cause an elevation in the SGOT level.
Clinical Significance:

High AST may indicate chronic alcohol ingestion, not limited to overt chronic alcoholism; cirrhosis and hepatitis.  High AST levels are also found in other types of liver disease, including earlier stages of hemochromatosis; chemical injury (eg, necrosis related to toxins such as carbon tetrachloride). Other causes of high AST include cholecystitis, Reye syndrome, trauma (including head trauma and including surgery) and other striated muscle diseases, including dystrophy, dermatomyositis, trichinosis, polymyositis, and gangrene.  Both AST ALT elevations are found with Duchenne muscular dystrophy.

In myocardial infarction AST peaks about 24 hours after infarct and returns to normal three to seven days later. AST also increases in congestive failure with centrilobular liver congestion, in which high LDon LD isoenzymes is found, and in pericarditis, myocarditis, pancreatitis, and other inflammatory states including Legionnaires' disease. In renal infarction, lung infarction and other disease entities leading to necrosis including large, necrotic tumors, hypothyroidism, hemolytic anemias and certain CNS diseases.

Drugs:

A large number of commonly used drugs have been reported to elevate AST: isoniazid, phenothiazines, erythromycin, progesterone, anabolic-androgenic steroids, halothane, methyldopa, opiates, indomethacin, salicylates in children, and other drugs. Hepatotoxicity from drugs, especially acetaminophen may cause high aminotransferase activity with elevation of AST:ALT ratio.

Low AST may indicateuremia, vitamin B6 deficiency (this can be corrected), metronidazole,trifluoperazine.

Causes for Rejection: Gross hemolysis; improper labeling.
Interfering Substances:

Hemolysis falsely elevates AST results.  Hemolyzed specimens should not be used.

Lipemia of 600 mg/dL, the magnitude of interference could not be determined.