Taurochenodeoxycholic acid (TCDCA) is a biomarker for the deficiency of sterol 27-hydroxylase caused by mutations in the CYP27A1 gene.  See also GlcA-tetrol and d6-GlcA-tetrol.
 
The absolute amount of d4-TCDCA in the vial was determined using quantitative NMR to have the stated value on the vial. The vial may have additional components, but none are isobaric with TCDCA or d4-TCDCA, and these additional components have no effect on the ability to quantify the TCDCA. 
 
 
Cerebrotendinous xanthomatosis ctx glcA-tetrol