Point-of-care β-hydroxybutyrate measurement for the diagnosis of feline diabetic ketoacidaemia.

OBJECTIVES

To evaluate accuracy and precision of a hand-held ketone meter measuring β-hydroxybutyrate and to determine its diagnostic performance to rule out ketoacidaemia in diabetic cats.

METHODS

The ketone meter was validated by calculating within-day precision at different β-hydroxybutyrate concentrations and by comparison with a laboratory method. To determine its diagnostic performance to diagnose ketoacidaemia, 217 sets of data (venous blood gas analysis and β-hydroxybutyrate measurements) were retrospectively analysed. Sensitivities and specificities were calculated with the help of receiver-operating characteristic curves.

RESULTS

The ketone meter reliably detected β-hydroxybutyrate at concentrations >0·1 mmol/L and reproducibility was acceptable. Measurements highly correlated with laboratory results (r=0·97; P<0·001), but a significant negative bias was found at high concentrations. A β-hydroxybutyrate concentration of >2·55 mmol/L had a sensitivity of 94% and a specificity of 68% for diagnosing ketoacidaemia. Many cats with high β-hydroxybutyrate concentrations and normal blood pH had an elevated chloride gap suggestive of superimposed hypochloraemic metabolic alkalosis.

CLINICAL SIGNIFICANCE

The commercially available point-of-care ketone meter Precision Xtra is a valid tool to measure β-hydroxybutyrate in diabetic cats. Concentration <2·55 mmol/L enable ketoacidaemia to be excluded and should lead to redirection of differential diagnoses.