Bile acids

See also:

Bile acids in lizards

Description

Bile acids are synthesised from cholesterol in the liver and are then conjugated with glycine or taurine. Feline bile acids are conjugated exclusively with taurine, partly explaining their high absolute requirement for this aminosulphonic acid. In contrast, rabbits conjugate their bile acids only with glycine. The conjugated bile acids are secreted into bile which then passes into the small intestine.

Bile acids participate in lipid digestion in the small intestine and a proportion are then reabsorbed in the ileum. These are extracted from the portal blood in the liver and re-secreted into bile, completing the entero-hepatic circulation of bile acids.

Clinical Significance

Serum bile acid concentration may be elevated in the following conditions:

• Portosystemic Shunt or Hepatic Microvascular Dysplasia, in which the portal blood is directed into the systemic circulation, disrupting the enterohepatic circulation.
• Small Intestinal Bacterial Overgrowth and Antibiotic Responsive Diarrhoea due to deconjugation of bile acids by intestinal bacteria.

Bile acids may not reach the intestine if the biliary tract is obstructed or ruptured. Deficiency of bile acids is extremely rare, even with severe hepatic insufficiency.