Blood concentration and disappearance of injected alanine and beta-hydroxybutyrate in surgical patients

The blood concentrations and the disappearance of injected beta-hydroxybutyrate (beta-OHB) and alanine were measured in 12 health subjects who had fasted overnight and in 25 surgical patients. Ten of the patients had had uncomplicated abdominal surgery two of five days before, six patients had moderate sepsis e.g. wound sepsis and nine patients had severe intra-abdominal sepsis. Separated bolus injections of beta-OHB and alanine were given intravenously and the blood concentration of the corresponding metabolite was measured over the following 40 mins. The disappearance of the injected metabolite was logarithmic, and the half-life (t 1/2) and clearance rate of the injected metabolite were calculated. The basal ketone concentration (beta-hydroxybutyrate and acetoacetate) were higher in the post operative group than in healthy subjects whereas the severely septic group had the same ketone concentration as the healthy subjects. Alanine concentration was significantly lower in the post-operative group. The t 1/2 and clearance rate of the injected metabolites were similar in all the groups for both beta-hydroxybutyrate and alanine. It is suggested that if the bolus is handled like the endogenously produced metabolite then the differences in concentration of beta-OHB and alanine in post-surgical and septic patients are likely to be due to changes in production rate.