Defective bile acid amidation: predicted features of a new inborn error of metabolism.

Biochemical and clinical features are predicted for an as yet unreported inborn error of metabolism, in which bile acids cannot be conjugated with glycine or taurine. Unconjugated cholic acid will be secreted into bile, be absorbed from the intestine, and become the predominant bile acid in bile and plasma. Other bile acids will be esterified with glucuronate and secreted into bile, but undergo little enterohepatic circulation. Cholestasis will not be present; the bile acid pool will be diminished and lipid absorption, especially that of fat-soluble vitamins, will be impaired. A secretory diarrhoea may occur, caused by increased bile acid concentrations in the colon. Awareness of this possible syndrome should aid in its identification; oral administration of bile acids conjugated with glycine or taurine should correct the metabolic and clinical abnormalities.