Hong Kong Med J 2002;8:172-6 | Number 3, June 2002
Evaluation of a new handheld biosensor for point-of-care testing of whole blood beta-hydroxybutyrate concentration
RWK Chiu, CS Ho, SF Tong, KF Ng, CW Lam
Department of Chemical Pathology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong
OBJECTIVES. To evaluate performance characteristics of the newly available handheld combined glucose and ketone meter for beta-hydroxybutyrate measurement.
DESIGN. Laboratory method evaluation.
MAIN OUTCOME MEASURES. Accuracy of beta-hydroxybutyrate measurement and effect of acetoacetate interference at clinically important beta-hydroxybutyrate levels.
RESULTS. Deming regression analysis of beta-hydroxybutyrate measurements assessed by the ketone sensor and a laboratory enzymatic method revealed a coefficient of determination of 0.989 (P<0.001). Passing-Bablok regression analysis showed a linear relationship between the two methods, ie Y= –0.32+1.13X. The 95% confidence interval of the slope and y-intercept were: slope=1.13 (95% confidence interval, 1.04 to 1.22); intercept= –0.32 (95% confidence interval, -0.59 to -0.06). The Bland-Altman plot showed a small proportional bias between the two methods. The mean bias ±2 standard deviations was between -0.53 and 0.67 mmol/L. Beta-hydroxybutyrate measurements made by the sensor were linear up to 6 mmol/L. Replicate analysis of two samples spiked with 3.6 mmol/L and 0.8 mmol/L of beta-hydroxybutyrate resulted in coefficients of variation of 3.3% and 13%, respectively. The presence of acetoacetate caused a negative interference in beta-hydroxybutyrate measurement. Beta-hydroxybutyrate recovery was 97.0% and 90.7% when the ketone body ratios were 6:1 and 3:1, respectively.
CONCLUSION. The analytical performance of the sensor, when operated according to manufacturer’s instructions, could meet the needs of point-of-care beta-hydroxybutyrate measurement. Additional clinical studies are needed to assess the benefits of introducing such an assay in a clinical setting.
Key words: 3-Hydroxybutyric acid; Ketones; Point-of-care systems
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