Canis ISSN: 2398-2942

Blood biochemistry: bile acids

Synonym(s): Bile salts

Contributor(s): Kathleen P Freeman, James Simpson

Overview

  • Cholic and chenodeoxycholic acids (primary bile acids) synthesized in liver from cholesterol → conjugated with taurine (preferred) or glycine 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 via portal vein, where extracted and re-excreted (enterohepatic circulation).
  • 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.
    Follow the diagnostic tree for Increased Total Serum Bile Acids in Dogs Increased Total Serum Bile Acids in Dogs.

Sampling

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Tests

Methodologies

  • Enzymatic: more common (and accurate).
  • Radio-immunoassay (RIA) (uncommon in veterinary laboratories).

Availability

  • Widely available at commercial laboratories.

Validity

Sensitivity

  • Increased by performing bile acid stimulation test.

Specificity

UK

  • Liver biopsy when [bile acid] >30 umol/l (depending on laboratory's normal values) may give more indication of specific cause.

US

  • Liver biopsy when [bile acid] 7.6 mg/l (depending on laboratory's normal values) may give more indication of specific cause Biopsy: hepatic.

Technique (intrinsic) limitations

  • Measurements of total serum bile acids (TSBA) not indicated when jaundice is present because hyperbilirubinemia is present and increased affecting TSBA.
  • TSBA may be warranted in icteric animal if hemolysis cannot be ruled out. If hemolytic disease is the cause of jaundice TSBA are expected to be within normal limits.
  • RIA method less accurate.
  • Interpret results in conjunction with other laboratory results (liver enzymes) and/or liver biopsy.

Technician (extrinsic) limitations

  • Depends on methodology.

Result Data

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Further Reading

Publications

Refereed papers

  • Recent references from VetMedResource and PubMed.
  • Allen L, Stobie D, Mauldin M & Baer K E (1999) Clinicopathologic fractures of dogs with hepatic or microvascular dysplasia with and without portosystemic shunts - 42 cases (1991-1996). JAVMA 214(2), 218-220.
  • Sevelius E (1995) Diagnosis and prognosis of chronic hepatitis and cirrhosis in dogs. JSAP 36(12), 521-528.
  • Tisdall P L, Tsoukalas G & Malik R (1995) Post-prandial serum bile acid concentrations and ammonia tolerance in Maltese dogs with and without hepatic vascular anomalies. Aust Vet J 72(4), 121-126.
  • Center S A, ManWarren T, Slater M R & Wilentz E (1991) Evaluation of 12-hour pre-prandial and 2-hour post-prandial serum bile acid concentrations for diagnosis of hepatobiliary disease in dogs. J Am Vet Clin Assoc 199(2), 217-226.
  • Sutherland R J (1989) Biochemical evaluation of the hepatobiliary system in dogs and cats. Vet Clin North Am Small Anim Pract 19(5), 899-927.

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.
  • Duncan J R, Prasse K W & Mahaffey E A (1994) Veterinary Laboratory Medicine. Clinical Pathology. 3rd edn. Iowa: Iowa University Press.


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