Determination of ketone body kinetics using a D-(-)-3-hydroxy(4,4,4-/sub 2/H/sup 3/)butyrate tracer

In studies where D-(-)-3-hydroxy(4,4,4-/sub 2/H/sup 3/)butyrate is employed as isotopic tracer in vivo, we have described a selected ion monitoring, gas-liquid chromatography-mass spectrometry micromethod which measures (/sub 2/H/sup 3/) tracer enrichment in 3-hydroxybutyrate and acetoacetate from 300-microliters blood samples. For plasma samples in the physiologic range, intra- and interassay precisions for each ketone averaged better than +/- 1% and +/- 2%, respectively. The use of the method was validated by comparing kinetic data obtained with the above tracer with simultaneous flux data obtained with conventional D-(-)-3-hydroxy(3-/sup 14/C)butyrate tracer in five fasted rats.