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Test ID: AST Aspartate Aminotransferase (AST) (GOT), Serum

Reporting Name

Aspartate Aminotransferase (AST), S

Useful For

Diagnosing and monitoring liver disease, particularly diseases resulting in a destruction of hepatocytes

Clinical Information

Aspartate aminotransferase (AST) is found in high concentrations in liver, heart, skeletal muscle, and kidney. AST is present in both cytoplasm and mitochondria of cells. In cases involving mild tissue injury, the predominant form of AST is that from the cytoplasm. Severe tissue damage results in more of the mitochondrial enzyme being released. High levels of AST can be found in cases such as myocardial infarction, acute liver cell damage, viral hepatitis, and carbon tetrachloride poisoning. Slight to moderate elevation of AST is seen in muscular dystrophy, dermatomyositis, acute pancreatitis, and crushed muscle injuries.

Interpretation

Elevated aspartate aminotransferase (AST) values are seen in parenchymal liver diseases characterized by a destruction of hepatocytes. Values are typically at least 10 times above the normal range. Levels may reach values as high as 100 times the upper reference limit, although 20- to 50-fold elevations are most frequently encountered. In infectious hepatitis and other inflammatory conditions affecting the liver, alanine aminotransferase (ALT) is characteristically as high as or higher than AST, and the ALT:AST ratio, which normally and in other condition is less than 1, becomes greater than unity. AST levels are usually elevated before clinical signs and symptoms of disease appear. Five- to 10-fold elevations of both AST and ALT occur in patients with primary or metastatic carcinoma of the liver, with AST usually being higher than ALT, but levels are often normal in the early stages of malignant infiltration of the liver. Elevations of ALT activity persist longer than do those of AST activity. Elevated AST values may also be seen in disorders affecting the heart, skeletal muscle, and kidney.

Analytic Time

Same day/1 day

Day(s) and Time(s) Performed

Monday through Sunday; Continuously

Clinical Reference

Tietz Textbook of Clinical Chemistry. Edited by CA Burtis, ER Ashwood. Philadelphia, WB Saunders Company, 1994

Method Name

Photometric Rate, L-Aspartate with Pyridoxyl-5-Phosphate

Specimen Type

Serum


Necessary Information


Patient's age and sex are required.



Specimen Required


Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Specimen Volume: 0.5 mL

Collection Instructions:

1. Serum gel tubes should be centrifuged within 2 hours of collection.

2. Red-top tubes should be centrifuged and aliquoted within 2 hours of collection.


Specimen Minimum Volume

0.25 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 7 days
  Frozen  30 days
  Ambient  7 days

Reference Values

Males

0-11 months: not established

1-13 years: 8-60 U/L

≥14 years: 8-48 U/L

Females

0-11 months: not established

1-13 years: 8-50 U/L

≥14 years: 8-43 U/L

Test Classification

This test has been cleared, approved or is exempt by the U.S. Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information

84450

LOINC Code Information

Test ID Test Order Name Order LOINC Value
AST Aspartate Aminotransferase (AST), S 30239-8

 

Result ID Test Result Name Result LOINC Value
AST Aspartate Aminotransferase (AST), S 30239-8
Mayo Clinic Laboratories | Endocrinology Catalog Additional Information:

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