Capillary blood beta-hydroxybutyrate measurement by reagent strip in diagnosing diabetic ketoacidosis.

OBJECTIVE: To compare blood beta-hydroxybutyrate (β-OHB) levels measured by reagent strip with serum ketone levels assessed by the nitroprusside reaction in diagnosing diabetic ketoacidosis (DKA). DESIGN: Prospective study of DKA in 19 Thai diabetic patients from September 2001 until August 2002. SETTING: A university hospital. PATIENTS: Nineteen patients with DKA and ten patients with metabolic acidosis from other causes. INTERVENTIONS: Capillary blood β-OHB was measured by a blood ketone meter (MediSense® Optium™). Concurrently, serum ketone was measured semiquantitatively by nitroprusside reaction (Ketostix®, N-multistix®, and Labstix®). MAIN OUTCOME MEASURE: Sensitivity, specificity, and ROC curve of both methods in diagnosing DKA. RESULT: Mean age ± SD of DKA patients was 45.6 ± 16.95 years. Plasma glucose was 675.25 ± 188.15 mg/dL, arterial blood pH 7.19 ± 0.12, anion gap and serum bicarbonate 29.93 ± 4.90 and 8 ± 3.35 mmol/L. Serum ketone was moderately to markedly positive in most cases. Capillary β-OHB ranged from 2.4 to >6 mmol/L. The sensitivity and specificity of serum ketone by nitroprusside reaction in diagnosing DKA were 95% and 100%. The sensitivity and specificity of capillary β-OHB was 90% and 100% respectively. The areas under ROC curves of serum ketone and capillary β-OHB were 0.975 and 0.950 (NS) respectively. CONCLUSION: Serum ketone and blood β-OHB measurement are equally effective in diagnosing DKA among uncomplicated cases. ABBREVIATIONS: β-OHB = beta-hydroxybutyrate; DKA = diabetic ketoacidosis; MA = metabolic acidosis; ROC = receiver operating characteristic.