Investigation of the metabolic pattern in maple syrup urine disease by means of glass capillary gas chromatography and mass spectrometry

Urine and serum from patients with maple syrup urine disease (MSUD) have been examined quantitatively and qualitatively using glass capillary gas chromatography in combination with mass spectrometry. During clinical episodes, patients with this disease were found to excrete increased amounts of the following metabolites in addition to the previously recognized branched-chain 2-keto and 2-hydroxy acids, lactate and 3-hydroxybutyrate; 2-hydroxybutyrate, 2-hydroxyisobutyrate, 3-hydroxyisovalerate, 3-hydroxylsobutyrate and 2-methyl-3-hydroxybutyrate. Most of the latter compounds seem to accompany ketoacidosis and lactic acidosis. The capillary column also separated the d- and l-forms of 2-keto-3-methylvalerate, and both isomers were, in contrast to earlier assumptions, present in the MSUD patients. The results clearly demonstrate that new information on the metabolic situation in well known disorders may be obtained by exploiting the high resolving power of capillary columns.