Due to the nature of the biochemical defect, the cholestanol concentration in plasma or serum (derived from blood) is high, while the plasma cholesterol concentration is normal to low. In addition, the concentration of bile acid pathway intermediates is elevated, and the concentration of bile alcohols in plasma, bile and urine is increased. Bile alcohols are formed in an alternative pathway present in CTX that generates some cholic acid. Due to the nature of the biochemical defect in CTX there is little or no formation of chenodeoxycholic acid.