canis - Articles
Blood biochemistry: alkaline phosphatase (ALP)
Synonym(s): ALP, Serum alkaline phosphatase, SAP
Overview
- Membrane associated enzyme.
- Number of isoenzymes produced in a range of tissues (liver, kidney, intestine, placenta).
- Special procedures are necessary to determine isoenzymes.
- Levamisole inhibition or heat activation commonly used to separate hepatic from steroidal isoenzymes as cause of increased activity.
- May see overlap in steroid and hepatic isoenzymes in many types of disease so not always helpful in separating underlying cause.
- Increased plasma levels are derived from liver and bone.
- Good indicator of liver disease and cholestasis - increases before plasma bilirubin.
- Corticosteroids induce a specific isoenzyme from the liver (steroid-induced alkaline phosphatase - SIAP/sALP).
Uses
Alone
- Identification of cholestasis.
- Screening for bone disease.
In combination
- As part of routine biochemical screening panel.
- Liver disease Liver: chronic disease - overview in conjunction with:
- Aspartate aminotransferase (AST) Blood biochemistry: aspartate aminotransferase (AST).
- Alanine aminotranferase (ALT) Blood biochemistry: alanine aminotransferase (SGPT, ALT).
- Gamma-glutamyltransferase (GGT) Blood biochemistry: gamma glutamyltransferase.
- Bile salts Blood biochemistry: bile acids.
- Investigation of suspected hyperadrenocorticism Hyperadrenocorticism.
Other points
- High levels of ALP (and GGT) occur in canine colostrum.
- May see <100x increase following colostral ingestion.
- May take approximately 10 days to return to within reference interval for adult dogs.
Sampling
Subscribe To View
This article is available to subscribers.
Try a free trial today or contact us for more information.
Tests
Methodologies
- Method and normal range may vary between laboratories.
- Electrophoretic or other separation method necessary to measure activity of individual isoenzymes, especially SIAP.
Availability
- Widely available.
- Routine test - contact laboratory to confirm availability of SIAP measurement.
Validity
Sensitivity
- Sensitive indicator of cholestasis or hyperadrenocorticism, but not specific.
Technique intrinsic limitations
- Test results most significant when interpreted in conjunction with other laboratory results and clinical findings.
Result Data
Subscribe To View
This article is available to subscribers.
Try a free trial today or contact us for more information.
Further Reading
Publications
Refereed papers
- Recent references from VetMedResource and PubMed.
- Center S A, Slater M R, ManWarren T et al (1992) Diagnostic efficacy of serum alkaline phosphatase and gamma-glutamyltransferase in dogs with histologically confirmed hepatobiliary disease - 277 cases (1980-1990). JAVMA 201, 1258.
Other sources of information
- Ettinger S J & Feldman E C (2000) Eds. Textbook of Veterinary Internal Medicine. 5th edn. W B Saunders & Co, USA.
- Kaneko J J, Harvey J W & Brass M L (1997) Eds. Clinical Biochemistry of Domestic Animals. 5th edn. Academic Press, USA.
- Duncan J R, Prasse K W & Mahaffey E A (1994) Veterinary Laboratory Medicine. Clinical Pathology. 3rd edn. Iowa University Press, USA.