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Test Details
Use
This assay uses LC/MS-MS to quantify the free acid, glycine-conjugate and taurine-conjugate forms of cholic acid, chenodeoxycholic acid, deoxycholic acid, and ursodeoxycholic acid. Bile acids may be measured to investigate obstructive cholestasis in pregnancy.1 In addition, bile acids are required for cholesterol absorption, fat-soluble vitamin absorption, and to provide resistance to overgrowth of intestinal bacteria.1 Bile acid levels may be reduced or elevated due to various genetic defects.
Methodology
High-pressure liquid chromatography/tandem mass spectrometry (HPLC/MS-MS)
Additional Information
Bile acids are formed in the liver from cholesterol, stored and concentrated in the gallbladder, and excreted into the intestines in response to food. The liver synthesizes cholesterol into two primary bile acids, cholic acid and chenodeoxycholic acid. The primary bile acids are converted by intestinal bacteria to the secondary bile acids, deoxycholic acid and lithocholic acid. A fraction of chenodeoxycholic acid is also transformed into the tertiary bile acid, ursodeoxycholic acid.
Specimen Requirements
Specimen
Serum (preferred) or plasma, frozen
Volume
1 mL
Minimum Volume
0.3 mL (Note: This volume does not allow for repeat testing.)
Container
Red-top tube, gel-barrier tube, lavender-top (EDTA) tube, or green-top (sodium heparin) tube
Patient Preparation
Patient should be fasting.
Collection
Serum/plasma must be separated from cells within two hours of venipuncture. Transfer serum/plasma to a plastic transport tube before freezing.
Storage Instructions
Refrigerate or freeze.
Stability Requirements
Temperature | Period |
|---|---|
Room temperature | 1 day |
Refrigerated | 3 days |
Frozen | 14 days |
Freeze/thaw cycles | Stable x6 |
Causes for Rejection
Whole blood
Clinical Information
Footnotes
1. Monte MJ, Marin JJ, Antelo A, Vazquez-Tato J. Bile acids: Chemistry, physiology, and pathophysiology. World J Gastroenterol. 2009; 15(7):804-816.19230041