Identification of 3-hydroxy-3-ethylglutaric acid in urine of patients with propionic acidaemia

By gas chromatographic mass spectrometric analysis, 3-hydroxy-3-ethylglutaric acid was identified in the urine of patients with propionyl CoA carboxylase deficiency. Simultaneously, large amounts of 3-hydroxyvaleric acid and 3-oxovaleric acid, as well as a number of metabolites previously well known in this disorder, were also found in the urine of the patients. It is suggested that formation of 3-oxovaleric acid and 3-hydroxyvaleric acid proceeds via 3-hydroxy-3-ethylglutaryl CoA as an intermediate by a mechanism similar to that of ketone body formation.