Alanine Aminotransferase (ALT) (GPT), Serum
Use
Alanine aminotransferase (ALT) is an enzyme primarily present in liver cells. It plays a crucial role in diagnosing and monitoring liver diseases, especially those associated with hepatic necrosis, such as viral hepatitis. An increase in serum ALT levels often occurs even before clinical signs and symptoms manifest, making it a vital indicator of liver cell integrity. ALT is a more liver-specific enzyme compared to aspartate aminotransferase (AST), as its elevations in the blood are rarely noted in other than parenchymal liver disease conditions.
Special Instructions
Patient's age and sex are required when submitting specimens. The preferred specimen container is a serum gel tube, but a red top tube is also acceptable. Serum gel tubes must be centrifuged within 2 hours of collection, and red-top tubes should be centrifuged and aliquoted within the same timeframe.
Limitations
ALT assays require pyridoxal phosphate to be present as a cofactor for optimal enzyme activity. Gross hemolysis in samples can lead to rejection of the specimen. ALT levels can reach values as high as 100 times above the upper normal range in some conditions, but such instances are not common. The ALT:AST ratio can be particularly informative; in certain liver conditions, this ratio exceeds unity.
New York Approved
Methodology
Automated Analyzer (Clinical Chemistry)
Biomarkers
LOINC Codes
- 1743-4
- 1743-4
Result Turnaround Time
1-2 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
0.5 mL
Minimum Volume
0.25 mL
Container
Serum gel or Red top
Collection Instructions
Serum gel tubes should be centrifuged within 2 hours of collection. Red-top tubes should also be centrifuged and aliquoted within 2 hours.
Storage Instructions
Refrigerated (preferred) for 7 days or Frozen for 7 days.
Causes for Rejection
Gross hemolysis
Stability Requirements
| Temperature | Period |
|---|---|
| Refrigerated | 7 days |
| Frozen | 7 days |