equis - Articles
Blood: biochemistry – bile acids
Synonym(s): Bile salts
Overview
- Cholic and chenodeoxycholic acids (primary bile acids) synthesized in liver from cholesterol → conjugated with taurine and excreted in bile as their sodium salts (bile salts).
- Discharged at time of eating to small intestine where they assist in fat digestion.
- Only 2-5% of total bile acids are lost in feces each day - remainder resorbed, pass to the liver where extracted and re-excreted.
- Small proportion reach general circulation - it is these that are measured.
- Sensitive indicator of liver function and of integrity of liver, biliary and intestinal circulation.
- The absence of a gall bladder in the horse means that bile acids are cycled continuously rather than released as a bolus at feeding. Therefore levels are not affected by feeding as in dogs.
- Highest concentrations associated with biliary obstructive disease and portosystemic shunts.
Uses
Alone
- Liver function - raised bile acids suggests functional compromise and guarded prognosis for hepatic repair. Serial samples help monitor response and clarify prognosis.
- Cholestasis.
In combination
- With clinical signs and results of other tests.
Sampling
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Tests
Methodologies
- Enzymatic: common.
Availability
- Commercial laboratory, widely available.
Validity
Sensitivity
- High sensitivity detection of decreased liver function.
Specificity
- Low specifity in determining cause of decreased liver function.
- Liver biopsy when [bile acid] elevated is necessary to determine specific cause Liver: biopsy .
Technique intrinsic limitations
- Interpret results in conjunction with other laboratory results (liver enzymes).
- Does not correlate with degree or type of liver disease. Prognosis depends on underlying cause.
Technician extrinsic limitations
- Depends on methodology.
Result Data
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Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
Other sources of information
- Barton M H & Morris D D (1998) Diseases of the Liver. In: Equine Internal Medicine. Eds: S M Reed & W M Bayly. W B Saunders Co, USA.
- Kaneko J J, Harvey J W & Bruss M L (1997) EdsClinical Biochemistry of Domestic Animals. 5th edn. Academic Press, USA.
Organisation(s)
- Veterinary commercial laboratories, State diagnostic laboratories or Veterinary College laboratories.