Kinetic Measurement of the Combined Concentrations of Acetoacetate and /3-Hydroxybutyrate in Serum

This is an automated method for the kinetic measurement of the combined concentrations of acetoacetate and f3-hydroxy-butyrate in a single channel of the “Muitistat III ” centrifugal analyzer. Acetoacetate is first reduced with high concentra-tions of NADH by catalysis with 3-hydroxybutyrate dehydro-genase (EC 1.1.1.30). This reaction mixture is diluted with excess NAD. The endogenous f3-hydroxybutyrate and that resulting from acetoacetate are then measured kinetically. Comparing the combined concentration of acetoacetate and p-hydroxybutyrate (y) with the sum of acetoacetate and /3-hydroxybutyrate measured as described by Hansen and Freier (Clin Chem 1 978;24:475) (x)yielded the relationship: y = 0.99x- 0.57 (r = 0.93, n = 25). The run-to-run CVs for low (5 mmol/L) and high (15 mmol/L) acetoacetate controls were 12 % and 6%, respectively. The method is useful for deter