Fructose load test--an in vivo screening test designed to assess pyruvate dehydrogenase activity and interconversion

An in vivo screening test is described, which is designed to assess the activity and interconversion of the human pyruvate dehydrogenase complex. Oral fructose was administered to six healthy subjects following (a) an overnight fast and (b) an oral glucose load. The rise in blood pyruvate and lactate levels following fructose was almost twice as great in the fasted state compared to the fed (post-glucose) state. It is proposed that this difference is due to the conversion of pyruvate dehydrogenase to its active form, following feeding.