Chemical structures and descriptions
Bile acids
What is measured?
7α-hydroxy-cholesten-3-one (C4), cholic acid (CA), glycocholic acid (GCA), taurocholic acid (TCA), chenodeoxycholic acid (CDCA), glycochenodeoxycholic acid (GCDCA), taurochenodeoxycholic acid (TCDCA), hyocholic acid (HCA), glycohyocholic acid (GHCA), taurohyocholic acid (THCA), tauro-alfa-muricholic acid (TaMCA), deoxycholic acid (DCA), glycodeoxycholic acid (GDCA), taurodeoxycholic acid (TDCA), lithocholic acid (LCA), glycolithocholic acid (GLCA), taurolithocholic acid (TLCA), lithocholic acid sulfate (LCAs), Iso-litocholic acid (iLCA), ursodeoxycholic acid (UDCA), glycoursodeoxycholic acid (GUDCA), tauroursodeoxycholic acid (TUDCA), hyodeoxycholic acid (HDCA), glycohyodeoxycholic acid (GHDCA), taurohyodeoxycholic acid (THDCA).
Method(s): LC-MS/MS
The bile acids
Bile acids are amphipathic molecules synthesized from cholesterol. They are categorized as primary (P) synthesized in the liver and secondary bile acids (S) that are produced in the colon by bacterial modification of primary bile acids; both types are subjected to conjugation (amidation) with glycine, taurine and may also undergo esterification, sulfation and glucuronidation. Most bile acids undergo enterohepatic circulation. Bile acids are essential for the digestion and absorption of dietary fats and fat-soluble vitamins, but have increasingly been recognized as signaling molecules across several tissues by serving as ligands for numerous receptors including FXR, TGR5, PXR, VDR and NR4A1.
Indication(s)
Circulating bile acids have been investigated in relation to (cholestatic) liver diseases, fatty liver disease, irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), short bowel syndrome, and Clostridium difficile infection, obesity, and cardiometabolic, inflammatory, neoplastic (cancerous) and neurodegenerative diseases.
Specimen, collection and processing
Whole blood should be sampled in cold EDTA tubes, preferentially put in liquid nitrogen, and stored at –80°C.Â
Transportation
Frozen, on dry ice. (for general instruction on transportation, click here)
Reported values, interpretation
Fasting serum/plasma total bile acid levels in healthy adults are typically 2–10 μmol/L. Cholic acid (CA) and chenodeoxycholic acid (CDCA) are present in roughly equal amounts, each typically less than 2–5 μmol/L). Deoxycholic acid (DCA) is the main secondary bile acid detected, with mean serum levels around 0.2 – 0.3 μmol/L. Conjugated primary bile acids (glycocholic and taurocholic acids) are the dominant forms measured in healthy controls, with mean total concentrations around 0.8–1.9 μmol/L.
Literature
1. Mohanty, I., Allaband, C., Mannochio-Russo, H., El Abiead, Y., Hagey, L. R., Knight, R. et al. (2024). The changing metabolic landscape of bile acids – keys to metabolism and immune regulation. Nat Rev Gastroenterol Hepatol, 21(7), 493-516.
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