Alanine Aminotransferase (ALT/SGPT)

 

CPT Code:  84460
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: Spectrophotometry (SP)
Collection: Complete clot formation should take place before centrifugation. Serum or plasma should be physically separated from cells as soon as possible within a maximum limit of two hours from the time of collection.
Reference Range: 12-78 IU/L

 

Stability:

 

 Temperatures  Period
 Refrigerated (2-8 ⁰C)
 14 Days
 Frozen (≤ -20 ⁰C)  1 month
Avoid repeated freezing and thawing. Thawed frozen specimens which are turbid must be clarified by centrifugation prior to testing.

 

Use: Alanine Aminotransferase (ALT) measurements are particularly useful in the diagnosis and management of certain liver diseases, e.g., viral hepatitis and cirrhosis.
Clinical Significance:  Significant elevations of ALT occur only in diseases of the liver. ALT is often measured in conjunction with AST to determine whether the source of the AST is the liver or the heart. ALT is normally not elevated in cases of myocardial infarction, i.e., a normal ALT, in conjunction with an elevated AST, tends to suggest cardiac disease. However, slight elevations of ALT may occur if an infarct destroys a very large volume of heart muscle.
Causes for Rejection: Gross hemolysis; excessive lipemia; improper labeling.
Limitations: Trauma to striated muscle, tissue, rhabdomyolysis, polymyositis, and dermatomyositis may produce increased results. Hemolyzed samples may yield elevated results. Some illegal drugs (cocaine, anabolic steroids, ecstasy) may also produce increased results.

 

Interfering Substances:

Bilirubin (unconjugated) at 60 mg/dL decreases ALTI result at an activity of 68 U/L by 11%.

Bilirubin (conjugated) at 40 mg/dL decreases ALTI results at an activity of 71 U/L by 13%

Bilirubin (conjugated) at 60 mg/dL decreases ALTI results at an activity of 144 U/L by 12%

Triglycerides above 400 mg/dL, the magnitude of the interference could not be determined.

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