Measurement of blood acetoacetate and β-hydroxybutyrate in an automatic analyser

g-hydroxybutyrate and acetoacetate as well as lactate and pyruvate are intermediary metabolites normally present in blood. The g-hydroxybutyrate/acetoacetate ratio is an expression of the mitochondrial oxido-reduction state. This ketone body ratio can provide a clue to diagnosis and metabolic status in congenital errors of the electron transport chain and pyruvate metabolism. The standardization of these analytical procedures improves the interpretation of the results helping in the difficult diagnosis of mitochondrial diseases in children. This study describes an adaptation to a Dimension R 2 L (Dade Behring, Newark, Delaware, USA) automatic analyser for a method to measure blood ketone bodies (g-hydroxybutyrate and acetoacetate). The method allows the metabolites to be measured directly in nondeproteinized plasma (fluoride/ethylenediaminetetraacetic acid). This adaptation simplifies the analytical procedure and limits the turnaround time to 20 minutes. With a sample volume of 200 μ l metabolite concentrations ranging from 12 to 1300 μ molL(−1) of g-hydroxybutyrate and from 10 to 450 μ molL(−1) of acetoacetate may be measured with a reliable analytical response.