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Bile acids are formed in the liver from cholesterol, conjugated primarily to glycine and taurine, stored and concentrated in the gallbladder, and secreted into the intestine after the ingestion of a meal. In the intestinal lumen, the bile acids serve to emulsify ingested fats and thereby promote digestion. During the absorptive phase of digestion, approximately 90% of the bile acids are reabsorbed.
The efficiency of the hepatic clearance of bile acids from portal blood maintains serum concentrations at low levels in normal persons. An elevated fasting level, due to impaired hepatic clearance, is a sensitive indicator of liver disease. Following meals, serum bile acid levels have been shown to increase only slightly in normal persons, but markedly in patients with various liver diseases, including cirrhosis, hepatitis, cholestasis, portal-vein thrombosis, Budd-Chiari syndrome, cholangitis, Wilson disease, and hemochromatosis. No increase in bile acids will be noted in patients with intestinal malabsorption. Metabolic hepatic disorders involving organic anions (eg, Gilbert disease, Crigler-Najjar syndrome, and Dubin-Johnson syndrome) do not cause abnormal serum bile acid concentrations.
Significant increases in total bile acids in non-fasting pregnant females can aid in the diagnosis at cholestasis. Other factors, such as complete medical history, physical exam and liver function tests should also be considered.
An aid in the evaluation of liver function
Evaluation of liver function changes before the formation of more advanced clinical signs of illness such as icterus
An aid in the determination of hepatic dysfunction as a result of chemical and environmental injury
An indicator of hepatic histological improvement in chronic hepatitis C patients responding to interferon treatment
An indicator for intrahepatic cholestasis of pregnancy
Total bile acids are metabolized in the liver and can serve as a marker for normal liver function. Increases in serum bile acids are seen in patients with acute hepatitis, chronic hepatitis, liver sclerosis, and liver cancer.
Serum total bile acids testing is generally not suitable for differentiation among the various types of liver diseases.
Total bile acids concentration is increased after meals; samples should be collected under fasting conditions.
< or =10 mcmol/L
Total Bile Acids Test and Clinical Diagnosis. D002 (06-2012), MK035 Rev.C. Diazyme Laboratories, Poway, CA