Letters Annals of Clinical Biochemistry 2015, Vol. 52(3) 413–415 acb.sagepub.com
Use of point-of-care blood ketone testing to diagnose and monitor patients with diabetic ketoacidosis In a recent editorial, Dhatariya1 discussed the use of point-of-care blood ketone monitors in the management of diabetic ketoacidosis (DKA) in adults. Following the publication of the Joint British Diabetes Society guidelines on the management of DKA in adults,2 we introduced blood ketone testing at the bedside using Abbott Precision Xceed Pro meters. Where possible, it is advisable that point-of-care testing (POCT) should be supported by a laboratory method for the same analyte, so that results outside the measurable range of the device, or results which are not consistent with the clinical picture, may be verified or otherwise. We, therefore, evaluated and introduced a laboratory method for betahydroxybutyrate (BHB). Like others, we found good agreement between results of POCT capillary ketone measurement using bedside meters, and laboratory BHB results obtained on venous serum samples, up to a concentration of 3 mmol/L.3,4 Above 3 mmol/L, POCT results were consistently lower than serum BHB measured on venous samples. For example, one patient had a capillary POCT ketone result of 5.4 mmol/L but a laboratory venous serum BHB of 13.7 mmol/L. Dhatariya is correct to point out that both results give a diagnosis of DKA and that the rate of decline is rarely if ever used in isolation to guide treatment. However, we think it is important that all users of POCT ketone meters are aware of this limitation. In our comparison study, some patients appeared to show no or very little response to treatment using capillary POCT ketone tests, whereas laboratory measurements on venous samples showed an appropriate decrease in BHB (>0.5 mmol/L/h).2 For example, one patient had a capillary POCT ketone result of 3.6 mmol/L initially, which decreased to 3.3 mmol/L after 5 h of treatment. By contrast, BHB laboratory results on venous samples collected simultaneously showed a fall from 12.7 mmol/L to 3.1 mmol/L. Capillary POCT ketone measurement alone may give a false impression that ketoacidosis is not resolving.
We also measured venous blood ketones using the same POCT meters and found good agreement with venous blood BHB measurements, suggesting that the falsely low results observed using capillary samples reflect the characteristics of capillary blood rather than the meter itself. Therefore, this limitation may potentially affect all POCT meters using capillary samples to measure ketones. We have introduced routine laboratory BHB analysis and incorporated venous BHB measurement into our local DKA guideline. We have also included a statement in our guideline to ensure that blood ketone monitoring is never used on its own to guide treatment: When blood ketones are >3.0 mmol/L, ketone meter measurements using capillary blood may underestimate the actual value and rate of change may also be falsely low. Review venous ketone results and also assess change in capillary glucose and venous bicarbonate to help determine if IV insulin rate needs to be changed.
We advise all hospitals using POCT capillary blood ketone testing to be aware of the possible limitations when using any bedside meters to measure blood ketones. The laboratory has an important role as with any POCT to ensure that all users are aware of any limitations. Declaration of conflicting interests None.
Funding This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.
Ethical approval Not applicable.
Guarantor JA.
Downloaded from acb.sagepub.com at KAI NAN UNIV on April 23, 2015
414
Annals of Clinical Biochemistry 52(3)
Contributorship JA and NH are authors of the letter.
References 1. Dhatariya K. The use of point-of-care blood ketone monitors in the management of diabetic ketoacidosis in adults. Ann Clin Biochem 2014; 51: 525–527. 2. Dhatariya K, Savage M, Kelly T, et al. Joint British Diabetes Societies Inpatient Care Group. The management of diabetic ketoacidosis in adults. 2nd ed., http:// www.diabetologists-abcd.org.uk/JBDS/JBDS_IP_DKA_ Adults_Revised.pdf (2013, accessed 1 September 2014). 3. Janssen MJ, Hendrickx BH, Habets-van der Poel CD, et al. Accuracy of the precision point of care ketone test examined by liquid chromatography tandem mass spectrometry (LC-MS/MS) in the same fingerstick sample. Clin Chem Lab Med 2010; 48: 1781–1784. 4. Armer J, Hunt N, Kaushal K, et al. Limitations to using point of care blood ketone testing to monitor treatment of diabetic ketoacidosis. Pract Diabet 2013; 30: 380–382.
Jane Armer and Natalie Hunt Department of Clinical Biochemistry, Royal Preston Hospital, Preston, Lancashire, UK Corresponding author: Jane Armer, Lancashire Teaching Hospitals NHS Foundation Trust, Royal Preston Hospital, Sharoe Green Lane, Preston PR2 9HT, UK. Email: [email protected] ! The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav acb.sagepub.com doi: 10.1177/0004563214564226 available online at http://acb.sagepub.com
range,3 and it is not clear if the identification of UMI predicts future adverse outcomes in this population and setting.2 In other words, detection of high-normal levels of high-sensitivity troponin may be difficult to intepret in clinical settings such as primary prevention or screening in particular. These recent papers2,3 have contributed to the ongoing debate about overuse and overdiagnosis using cardiac troponin testing.4 Some of the questions that arise are: How, to what extent or in what situations should hs-cTnI assays be used? What are the economic implications of hs-cTnI assays? The need for age-, gender- and race-specific reference intervals for hscTnI has been highlighted1, and investigators agree on the need to standardize the currently available hs-TnI assays, since a 2.5-fold difference in the 99th percentile of the hs-cTnI level has been reported in these assays in healthy people.5 Herein, we would further like to stress the added value of using repeated measurements in the same subject. For example, in the acute phase, the changes seen in 2-hour repeated measurements of hs-cTnI in comparison to at-baseline one-time measurement, may permit more accurate diagnosis of acute myocardial infarction.1 The optimal interval between the first and second measurements remains to be determined in not only acute, but also chronic settings (e.g. primary prevention or mass screening); a monitoring duration of within five years in a chronic phase may be proposed based on a recent paper about the association between hs-TnI and U-MI.2 More research ideas for improving the application of hs-cTnI in the clinical setting are needed. Competing interests and Funding None.
High-sensitivity cardiac troponin I in the clinical setting: a rapidly developing field Substantial progress in the identificaion of patients at increased risk of cardiovascular disease has been made through the development of high-sensitivity troponin assays. These assays are used in increasingly diverse clinical settings, including preventive medicine.1 By way of example, high-sensitivity cardiac troponin I (hs-cTnI) has recently been reported to perform well at the 99th percentile of the reference population.2 hs-cTnI may be used to predict the development of unrecognized myocardial infarction (U-MI) in community-living older people, although the cutoff level for hscTnI for predicting U-MI was within the reference
Ethical approval Not applicable.
Guarantor KK.
Contributorship All authors wrote the manuscript and approved the final version.
References 1. Vasikaran SD, Macdonald SP and Sikaris KA. Highsensitivity cardiac troponin assays for risk stratification and for the diagnosis of acute myocardial infarction. Ann Clin Biochem 2012; 49: 209–210.
Downloaded from acb.sagepub.com at KAI NAN UNIV on April 23, 2015
Use of point-of-care blood ketone testing to diagnose and monitor patients with diabetic ketoacidosis In a recent editorial, Dhatariya1 discussed the use of point-of-care blood ketone monitors in the management of diabetic ketoacidosis (DKA) in adults. Following the publication of the Joint British Diabetes Society guidelines on the management of DKA in adults,2 we introduced blood ketone testing at the bedside using Abbott Precision Xceed Pro meters. Where possible, it is advisable that point-of-care testing (POCT) should be supported by a laboratory method for the same analyte, so that results outside the measurable range of the device, or results which are not consistent with the clinical picture, may be verified or otherwise. We, therefore, evaluated and introduced a laboratory method for betahydroxybutyrate (BHB). Like others, we found good agreement between results of POCT capillary ketone measurement using bedside meters, and laboratory BHB results obtained on venous serum samples, up to a concentration of 3 mmol/L.3,4 Above 3 mmol/L, POCT results were consistently lower than serum BHB measured on venous samples. For example, one patient had a capillary POCT ketone result of 5.4 mmol/L but a laboratory venous serum BHB of 13.7 mmol/L. Dhatariya is correct to point out that both results give a diagnosis of DKA and that the rate of decline is rarely if ever used in isolation to guide treatment. However, we think it is important that all users of POCT ketone meters are aware of this limitation. In our comparison study, some patients appeared to show no or very little response to treatment using capillary POCT ketone tests, whereas laboratory measurements on venous samples showed an appropriate decrease in BHB (>0.5 mmol/L/h).2 For example, one patient had a capillary POCT ketone result of 3.6 mmol/L initially, which decreased to 3.3 mmol/L after 5 h of treatment. By contrast, BHB laboratory results on venous samples collected simultaneously showed a fall from 12.7 mmol/L to 3.1 mmol/L. Capillary POCT ketone measurement alone may give a false impression that ketoacidosis is not resolving.
We also measured venous blood ketones using the same POCT meters and found good agreement with venous blood BHB measurements, suggesting that the falsely low results observed using capillary samples reflect the characteristics of capillary blood rather than the meter itself. Therefore, this limitation may potentially affect all POCT meters using capillary samples to measure ketones. We have introduced routine laboratory BHB analysis and incorporated venous BHB measurement into our local DKA guideline. We have also included a statement in our guideline to ensure that blood ketone monitoring is never used on its own to guide treatment: When blood ketones are >3.0 mmol/L, ketone meter measurements using capillary blood may underestimate the actual value and rate of change may also be falsely low. Review venous ketone results and also assess change in capillary glucose and venous bicarbonate to help determine if IV insulin rate needs to be changed.
We advise all hospitals using POCT capillary blood ketone testing to be aware of the possible limitations when using any bedside meters to measure blood ketones. The laboratory has an important role as with any POCT to ensure that all users are aware of any limitations. Declaration of conflicting interests None.
Funding This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.
Ethical approval Not applicable.
Guarantor JA.
Downloaded from acb.sagepub.com at KAI NAN UNIV on April 23, 2015
414
Annals of Clinical Biochemistry 52(3)
Contributorship JA and NH are authors of the letter.
References 1. Dhatariya K. The use of point-of-care blood ketone monitors in the management of diabetic ketoacidosis in adults. Ann Clin Biochem 2014; 51: 525–527. 2. Dhatariya K, Savage M, Kelly T, et al. Joint British Diabetes Societies Inpatient Care Group. The management of diabetic ketoacidosis in adults. 2nd ed., http:// www.diabetologists-abcd.org.uk/JBDS/JBDS_IP_DKA_ Adults_Revised.pdf (2013, accessed 1 September 2014). 3. Janssen MJ, Hendrickx BH, Habets-van der Poel CD, et al. Accuracy of the precision point of care ketone test examined by liquid chromatography tandem mass spectrometry (LC-MS/MS) in the same fingerstick sample. Clin Chem Lab Med 2010; 48: 1781–1784. 4. Armer J, Hunt N, Kaushal K, et al. Limitations to using point of care blood ketone testing to monitor treatment of diabetic ketoacidosis. Pract Diabet 2013; 30: 380–382.
Jane Armer and Natalie Hunt Department of Clinical Biochemistry, Royal Preston Hospital, Preston, Lancashire, UK Corresponding author: Jane Armer, Lancashire Teaching Hospitals NHS Foundation Trust, Royal Preston Hospital, Sharoe Green Lane, Preston PR2 9HT, UK. Email: [email protected] ! The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav acb.sagepub.com doi: 10.1177/0004563214564226 available online at http://acb.sagepub.com
range,3 and it is not clear if the identification of UMI predicts future adverse outcomes in this population and setting.2 In other words, detection of high-normal levels of high-sensitivity troponin may be difficult to intepret in clinical settings such as primary prevention or screening in particular. These recent papers2,3 have contributed to the ongoing debate about overuse and overdiagnosis using cardiac troponin testing.4 Some of the questions that arise are: How, to what extent or in what situations should hs-cTnI assays be used? What are the economic implications of hs-cTnI assays? The need for age-, gender- and race-specific reference intervals for hscTnI has been highlighted1, and investigators agree on the need to standardize the currently available hs-TnI assays, since a 2.5-fold difference in the 99th percentile of the hs-cTnI level has been reported in these assays in healthy people.5 Herein, we would further like to stress the added value of using repeated measurements in the same subject. For example, in the acute phase, the changes seen in 2-hour repeated measurements of hs-cTnI in comparison to at-baseline one-time measurement, may permit more accurate diagnosis of acute myocardial infarction.1 The optimal interval between the first and second measurements remains to be determined in not only acute, but also chronic settings (e.g. primary prevention or mass screening); a monitoring duration of within five years in a chronic phase may be proposed based on a recent paper about the association between hs-TnI and U-MI.2 More research ideas for improving the application of hs-cTnI in the clinical setting are needed. Competing interests and Funding None.
High-sensitivity cardiac troponin I in the clinical setting: a rapidly developing field Substantial progress in the identificaion of patients at increased risk of cardiovascular disease has been made through the development of high-sensitivity troponin assays. These assays are used in increasingly diverse clinical settings, including preventive medicine.1 By way of example, high-sensitivity cardiac troponin I (hs-cTnI) has recently been reported to perform well at the 99th percentile of the reference population.2 hs-cTnI may be used to predict the development of unrecognized myocardial infarction (U-MI) in community-living older people, although the cutoff level for hscTnI for predicting U-MI was within the reference
Ethical approval Not applicable.
Guarantor KK.
Contributorship All authors wrote the manuscript and approved the final version.
References 1. Vasikaran SD, Macdonald SP and Sikaris KA. Highsensitivity cardiac troponin assays for risk stratification and for the diagnosis of acute myocardial infarction. Ann Clin Biochem 2012; 49: 209–210.
Downloaded from acb.sagepub.com at KAI NAN UNIV on April 23, 2015
