Blood biochemistry: alanine aminotransferase (SGPT, ALT)
(ALT, Serum ALT, SALT, Glutamic-pyruvic transaminase, GPT, Serum GPT, SGPT)
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Overview
- ALT may be elevated with liver or muscle damage/disease.
- Highest concentration in hepatocytes, so considered most sensitive for hepatocellular damage.
- Transaminase (similar to AST).
- No isoenzymes.
Uses
In combination
- Detection of liver damage in conjunction with:
- Aspartate aminotransferase (AST)
 . - Alkaline phosphatase (ALP) .
- Bile acids .
- Albumin.
Source of test material
- Standard venipuncture .
- Serum usually preferred, or heparinized plasma may be used. Check with laboratory regarding preferred or alternative specimen.
- See biochemistry for information on handling and storage.
- For sample tube preference see
 .
Quantity of test material
- 2 ml serum or plasma. Check with laboratory regarding minimum recommended volume for single test or in combination with other tests.
Quality control
Precautions
Timing of test
- Fast animal for 8-12 h before sampling to prevent sample lipemia.
Sample storage
- Refrigerate prior to despatch.
- Avoid excessive temperatures.
Sample transport
- Standard postal times adequate.
- Package according to Post Office regulations .
- Avoid excessive temperatures.
- Separate serum/plasma before despatch.
Availability
Technique (intrinsic) limitations
- Results best interpreted in conjunction with other laboratory tests and clinical findings.
Normal (reference) values
- 20-100 iu/l.
- Some variation with method - individual laboratories should supply reference intervals for their test.
- Following isolated liver damage, levels peak in 3-4 hours and return to normal 10-14 days later.
- Persistently elevated levels indicate ongoing damage.
Abnormal values
Increased [ALT] - Acute infectious hepatitis .
- Toxic hepatitis .
- Chronic active hepatitis (autoimmune disorders, copper storage disease ).
- Acute pancreatitis .
- Severe shock (poor hepatic perfusion/hypoxia).
- Primary hepatic neoplasia .
- Hepatic amyloidosis .
- Secondary liver disease (hyperadrenocorticism , diabetes mellitus ).
Decreased [ALT] - Cephalosporin treatment.
- Increased lactate may interfere with enzymatic reaction used for measurement.
Errors and Artifacts
- Drugs including phenytoin , primidone and glucocorticoids can induce increases in ALT.
- Cephalosporin treatment may result in decreased ALT.
Publications
Refereed papers
- Sivenson C L & Graves T K (1997) Absence of liver specificity for canine alanine aminotransferase (ALT). Vet Clin Pathol 26 (1), 26-28.
Other sources of information
- Ettinger S J & Feldman E C (eds) (2000) Textbook of Veterinary Internal Medicine. 5th edn. Philadelphia: W B Saunders & Co.
- Kaneko J J, Harvey J W & Brass M L (eds) (1997) Clinical Biochemistry of Domestic Animals. 5th edn. Boston: Academic Press.
Vetstream contributor(s)
- Dr Kathleen Freeman DVM MS PhD MRCVS , Idexx Laboratories, PO Box 4, Wetherby, West Yorkshire LS22 4ZR, UK.
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