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HelpMayo Test ID ALT Alanine Aminotransferase (ALT) (GPT), 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.
Useful For
Diagnosis and monitoring of liver disease associated with hepatic necrosis
Method Name
Photometric Rate, L-Alanine with Pyridoxal-5-Phosphate
Reporting Name
Alanine Aminotransferase (ALT), SSpecimen Type
SerumSpecimen Minimum Volume
0.25 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 7 days | |
| Frozen | 7 days |
Reject Due To
| Gross hemolysis | Reject |
Clinical Information
Alanine aminotransferase (ALT) is present primarily in liver cells. In viral hepatitis and other forms of liver disease associated with hepatic necrosis, serum ALT is elevated even before the clinical signs and symptoms of the disease appear. Although serum levels of both aspartate aminotransferase (AST) and ALT become elevated whenever disease processes affect liver cell integrity, ALT is a more liver-specific enzyme. Serum elevations of ALT are rarely observed in conditions other than parenchymal liver disease. Moreover, the elevation of ALT activity persists longer than does AST activity.
Reference Values
Males
≥1 year: 7-55 U/L
Reference values have not been established for patients who are <12 months of age.
Females
≥1 year: 7-45 U/L
Reference values have not been established for patients who are <12 months of age.
Interpretation
Elevated alanine aminotransferase (ALT) 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, ALT is characteristically as high as or higher than aspartate aminotransferase (AST), and the ALT:AST ratio, which normally and in other condition is less than 1, becomes greater than unity. ALT levels are usually elevated before clinical signs and symptoms of disease appear.
Cautions
Pyridoxal phosphate is a cofactor in the reaction and must be present for optimal enzyme activity.
Clinical Reference
Tietz Textbook of Clinical Chemistry. Edited by CA Burtis, ER Ashwood. Philadelphia, WB Saunders Company, 1994
Method Description
Alanine aminotransferase (ALT) activity is determined by a kinetic method using a coupled enzyme reaction where the rate of NADH consumption is measured at 340 nm. The NADH decrease is directly proportional to the ALT activity.(Package insert: Roche ALT reagent, Indianapolis, IN, January 2000)
Day(s) Performed
Monday through Sunday
Report Available
Same day/1 to 2 daysSpecimen Retention Time
1 weekPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test has been cleared, approved, or is exempt by the US 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
84460
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| ALT | Alanine Aminotransferase (ALT), S | 1743-4 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| ALT | Alanine Aminotransferase (ALT), S | 1743-4 |