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Sources Of Errors In Glucose Oxidase

Accuracy Of Handheld Blood Glucose Meters At High Altitude

Accuracy Of Handheld Blood Glucose Meters At High Altitude

Abstract Due to increasing numbers of people with diabetes taking part in extreme sports (e.g., high-altitude trekking), reliable handheld blood glucose meters (BGMs) are necessary. Accurate blood glucose measurement under extreme conditions is paramount for safe recreation at altitude. Prior studies reported bias in blood glucose measurements using different BGMs at high altitude. We hypothesized that glucose-oxidase based BGMs are more influenced by the lower atmospheric oxygen pressure at altitude than glucose dehydrogenase based BGMs. Methodology/Principal Findings Glucose measurements at simulated altitude of nine BGMs (six glucose dehydrogenase and three glucose oxidase BGMs) were compared to glucose measurement on a similar BGM at sea level and to a laboratory glucose reference method. Venous blood samples of four different glucose levels were used. Moreover, two glucose oxidase and two glucose dehydrogenase based BGMs were evaluated at different altitudes on Mount Kilimanjaro. Accuracy criteria were set at a bias <15% from reference glucose (when >6.5 mmol/L) and <1 mmol/L from reference glucose (when <6.5 mmol/L). No significant difference was observed between measurements at simulated altitude and sea level for either glucose oxidase based BGMs or glucose dehydrogenase based BGMs as a group phenomenon. Two GDH based BGMs did not meet set performance criteria. Most BGMs are generally overestimating true glucose concentration at high altitude. At simulated high altitude all tested BGMs, including glucose oxidase based BGMs, did not show influence of low atmospheric oxygen pressure. All BGMs, except for two GDH based BGMs, performed within predefined criteria. At true high altitude one GDH based BGM had best precision and accuracy. Continue reading >>

S41 - The Impact Of Preanalytical Factors On Glucose Concentration Measurement

S41 - The Impact Of Preanalytical Factors On Glucose Concentration Measurement

S41 - The impact of preanalytical factors on glucose concentration measurement Nora Nikolac. The impact of preanalytical factors on glucose concentration measurement. Biochemia Medica 2014;24(Suppl 1):S41-S44 University Department of Chemistry, Medical School University Hospital Sestre Milosrdnice, Zagreb, Croatia Corresponding author: nora [dot] nikolac [at] gmail [dot] com Glucose is the most commonly ordered test in a clinical chemistry laboratory accounting for about 30-40% of the total laboratory workload. Measurement of glucose concentration is done in all types of samples: capillary and venous whole blood and plasma, serum, pleural fluid, ascites, cerebrovascular fluid and urine. Most of these measurements are included into healthcare of patients with diabetes mellitus. Diabetes mellitus is diagnosed based on the well-established cut-off values originating from the worldwide-accepted guidelines. When performing glucose tolerance tests, changes in glucose concentration indicate the degree of glucose metabolism impairment. Therefore, all factors influencing glucose concentration variability have to be minimized in order to obtain accurate results. Fortunately, nowadays, there are practically no analytical challenges for glucose concentration measurement. Automated methods used in the laboratories fulfil strict criteria with very low analytical variability. However, the biggest pitfall, as for all other laboratory measurements, lies in the preanalytical phase, which is, almost exclusively, responsible for the errors in glucose concentration measurement. A large number of preanalytical factors like sample type, transport conditions, time from blood sampling, temperature and type of test tube influence glucose concentration. Each of these factors introduces a certain Continue reading >>

Glucose Meters: Where Are We Now? Where Are We Heading?

Glucose Meters: Where Are We Now? Where Are We Heading?

Glucose meters: Where are we now? Where are we heading? Glucose meters have a rich history. Dating back to 1970, the first glucose meter is thought to have been the Ames Reflectance Meter (ARM), a portable meter weighing around three pounds and designed to detect the colorimetric signal formed on the Detrostix. Over the next 20 years the technology evolved into the small, lightweight, and portable meters we know today, sold in pharmacy and retail centers. Within this same timeframe that glucose meters migrated into the hospital, along the way the meters were redesigned to incorporate familiar features such as quality control (QC) lockout, operator login/management, and interface with the laboratory and hospital information systems. Fast forward to the present day, and glucose meters are ubiquitous in the hospital, found in almost every unit and used for a variety of reasonsfrom identifying hypoglycemia in neonatal wards to guiding intravenous insulin titration in tight glycemic control protocols aimed at controlling a patients blood glucose concentration. Irrespective of their look and their location-dependent (home vs. hospital) features, glucose meters in the home and hospital share a common principle of measurement. When whole blood is applied to the test strip, enzymes embedded within sense the glucose and generate either an electrical or colorimetric signal which is directly proportional to the activity of glucose. This activity is subsequently converted into concentration and reported as plasma equivalents. Virtually all meters utilize either glucose oxidase or glucose dehydrogenase enzyme as the sensor. Glucose meters are routinely used in the management of dysglycemiadisorders of blood sugar metabolism characterized by hypoglycemia and hyperglycemia. The most p Continue reading >>

Wo2012084194a1 - Systems And Methods To Compensate For Sources Of Error During Electrochemical Testing - Google Patents

Wo2012084194a1 - Systems And Methods To Compensate For Sources Of Error During Electrochemical Testing - Google Patents

WO2012084194A1 - Systems and methods to compensate for sources of error during electrochemical testing - Google Patents Systems and methods to compensate for sources of error during electrochemical testing WO2012084194A1 PCT/EP2011/006429 EP2011006429W WO2012084194A1 WO 2012084194 A1 WO2012084194 A1 WO 2012084194A1 EP 2011006429 W EP2011006429 W EP 2011006429W WO 2012084194 A1 WO2012084194 A1 WO 2012084194A1 Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.) G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES G01N27/00Investigating or analysing materials by the use of electric, electro-chemical, or magnetic means G01N27/26Investigating or analysing materials by the use of electric, electro-chemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis G01N27/30Electrodes, e.g. test electrodes; Half-cells G01N27/327Biochemical electrodes electrical and mechanical details of in vitro measurements G01N27/3271Amperometric enzyme electrodes for analytes in body fluids, e.g. glucose in blood G01N27/3274Corrective measures, e.g. error detection, compensation for temperature or hematocrit, calibration A technique for determining analyte concentration includes applying a first electrical potential excitation pulse to a body fluid sample in an analyte sensor, and a first current response of the body fluid sample to the first pulse is measured. A second excitation pulse is applied to the body fluid sample in the analyte sensor, and a second current response of the body fluid sample to the second pulse is measured. An analyte level in the body fluid sam

Capillary Glucose Meter Accuracy And Sources Of Error In The Ambulatory Setting

Capillary Glucose Meter Accuracy And Sources Of Error In The Ambulatory Setting

Glucose results derived from hand-held meters are used by patients and their health care team to make therapeutic decisions such as insulin dosing. Incorrect glucose values may result in both acute and also long-term therapeutic consequences. It is therefore essential that results are as accurate and precise as possible. Meter technology has shown incremental improvements since the introduction of the first commercially available hand-held meters in 1970s, including improvements in ease of use, technical performance and affordability.1-3Capillary glucose testing is an international multi-billion dollar industry.2 In New Zealand reimbursement of test strips for the 12 months to June 2009 was $19 million, accounting for 40% of PHARMAC’s entire diabetes ‘spend’. The number of meters available has expanded, both in New Zealand as well as internationally.1,2 Currently in New Zealand, six different meters are available for use with PHARMAC funded strips (see Table 1). It is therefore timely to describe current meter technology from a clinical perspective, highlighting some of the limits of meter performance. This review focuses on technical issues that impact on clinical interpretation of meter results in the ambulatory setting. It does not aim to be a comprehensive technical discussion. Although there are additional meter systems available in New Zealand with unsubsidised strips such as the Glucocard, which is used in many hospital inpatient settings, the focus of this review is meters with subsidised strips. Recent developments in meter technology have improved this testing system’s ease of use and analytical robustness.1-3 Test strips now require 8μL or less of blood (see Table 1). Using a low blood volume system has the following advantages: It allows most patien Continue reading >>

Uncertainty In The Determination Of Glucose And Sucrose In Solutions With Chitosan By Enzymatic Methods

Uncertainty In The Determination Of Glucose And Sucrose In Solutions With Chitosan By Enzymatic Methods

Uncertainty in the determination of glucose and sucrose in solutions with chitosan by enzymatic methods Berta N. Estevinho; Amlia Ferraz; Lcia Santos; Fernando Rocha; Arminda Alves * Laboratrio de Engenharia de Processos, Ambiente e Energia (LEPAE), Departamento de Engenharia Qumica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, s/n, 4200-465 Porto, Portugal The purpose of this work was to evaluate the applicability of two enzymatic methods to quantify glucose and sucrose in aqueous solutions with chitosan. The analytical methods were validated and the main parameters, as limit of detection, linearity range, precision and accuracy were determined. The global uncertainty for glucose enzymatic method was less than 10% for concentration levels between 700 and 2000 mg L-1, and for the sucrose enzymatic method, the global uncertainty showed values less than 3% for all concentration levels analyzed (100-1000 mg L-1). Despite the similarities of performances with respect to other analytical methods, the enzymatic method proved to be better than others, in particular high performance liquid-chromatography (HPLC), mainly if a great number of samples needs to be analyzed, allowing a quick result, and because the mucoadhesive properties of chitosan make difficult the HPLC analytical methodology, creating stability problems in the chromatographic column. Keywords: uncertainty, enzymatic methods, glucose, sucrose, chitosan O objetivo deste trabalho foi determinar a aplicabilidade de dois mtodos enzimticos um para a quantificao da glucose e outro da sacarose em solues aquosas contendo quitosano. Os mtodos analticos foram validados e os principais parmetros determinados como limite de deteco, intervalo de linearidade, preciso e exatido. A incerteza global d Continue reading >>

Preanalytical Variables And Factors That Interfere With The Biochemical Parameters: A Review

Preanalytical Variables And Factors That Interfere With The Biochemical Parameters: A Review

1. Plebani M . Errors in clinical laboratories or errors in laboratory medicine? ClinChem Lab Med. 2006;44(6):750-9. 2. Astion ML, Shojania KG, Hamill TR, Kim S, Ng VL. Classifying laboratory incident reports to identify problems that jeopardize patient safety. Am J ClinPathol 2003 Jul;120(1):18-26. 3. Branco BC, Inaba K, Doughty R, Brooks J, Barmparas G, Shulman I. The increasing burden of phlebotomy in the development of anaemia and need for blood transfusion amongst trauma patients. Injury 2012 Jan;43(1):78-83. 4. Hawkins R . Managing the pre- and post-analytical phases of the total testing process. Ann Lab Med 2012 Jan;32(1):5-16. 5. Lippi G, Becan-McBride K, Behulov D, Bowen RA, Church S, Delanghe J. Preanalytical quality improvement: in quality we trust. ClinChem Lab Med 2013 Jan;51(1):229-41. 6. Lippi G, Salvagno GL, Montagnana M, Guidi GC. Short-term venous stasis influences routine coagulation testing. Blood Coagul Fibrinolysis 2005 Sep;16(6):453-8. 7. Stankovic AK, Smith S. Elevated serum potassium values: the role of preanalytic variables. Am J ClinPathol 2004 Jun;121(Suppl.):105-12. 8. Herr RD, Swanson T. Pseudometabolic acidosis caused by underfill of Vacutainer tubes. Ann Emerg Med 1992 Feb;21(2):177-80. 9. Fukugawa Y, Ohnishi H, Ishii T, Tanouchi A, Sano J, Miyawaki H. Effect of carryover of clot activators on coagulation tests during phlebotomy. Am J ClinPathol 2012 Jun;137(6):900-3. 10. . Clinical and Laboratory Standards Institute (CLSI). Procedures for the collection of diagnostic blood specimens by venipuncture; approved standard 6th ed. Wayne (PA):CLSI; 2007 Document nr H3-A6.. 11. Egidi MG, D' Alessandro A, Mandarella G, Zolla L. Troubleshooting in platelet storage temperature and new perspectives through proteomics. Blood Transfus 2010 June;8(Sup Continue reading >>

Principles And Problems Of Blood Glucose Measurement

Principles And Problems Of Blood Glucose Measurement

Although blood glucose measurement is commonly performed, the use of a whole-blood sample introduces complications and compromise in terms of the assay principle, the method of calibration and the expression of results. Most point-of-care systems are calibrated against a method chosen by the manufacturer for reference purposes and assumptions are made, not necessarily valid ones, that blood samples from different individuals will behave similarly in both the reference and point-of-care methods. While most conventional laboratory techniques measure blood glucose as concentration in plasma or whole blood, direct-reading electrode systems measure it as molality in mmol/kg water, which is numerically greater, but results are often factorized and expressed, e.g. as plasma glucose concentration. However, there is inconsistency and the variety of techniques and principles leads to some difficulty in comparing results of blood glucose measurements by different methods. It has been proposed that some uncertainty could be eliminated by expressing all results as plasma glucose concentration, irrespective of specimen type or analytical method used. Variation in blood sampling site can also introduce errors, especially in point-of-care testing. Introduction The measurement of glucose is one of the longest established and most frequently performed tests in the clinical biochemistry laboratory. Surprisingly, despite the availability of purified reference standards, calibration of blood glucose methods can be extremely complex and, in some cases, rather approximate. This often stems from the fact that different techniques assay the glucose present in different fractions of the blood sample. They may employ different analytical principles to do this and may even express the results in a Continue reading >>

Factors Affecting Blood Glucose Monitoring: Sources Of Errors In Measurement

Factors Affecting Blood Glucose Monitoring: Sources Of Errors In Measurement

Go to: Measuring Accuracy Accuracy of a blood glucose meter is a measure of how closely the average of a series of values reflects the reference value. As seen in Figure 1 (left), the average of a series of values can be perfectly accurate, although none of the individual values is representative of the reference. Precision describes the reproducibility of a series of values, independent of the closeness of any of the values to the reference. Again, as seen in Figure 1 (center), a series of values can be highly precise, although none of the individual values is representative of the reference. Only when a series of values is both accurate and precise (Figure 1, right) do the individual values actually reflect the reference value. Figure 2 shows these same definitions applied to SMBG. The green line defines perfect accuracy. As seen on the left, a series of measurements, half of which are high by 100 mg/dl and half low by 100 mg/dl, would be considered perfectly accurate as a set since the high values and the low values would average to the true value. Conversely, as seen in the center of Figure 2, a series of measurements, each of which is high by 100 mg/dl, would be considered perfectly precise although biased. As seen on the right in Figure 2, only when a series of values are both accurate and precise do all of the values fall exactly on the green line of accuracy. The best single measure of both accuracy and precision is the mean absolute relative error (MARE) (also called mean absolute relative deviation or MARD and mean absolute error or MAE). Mean absolute relative error is calculated by taking the average for the set of individual absolute errors relative to its reference value (Figure 3). So, for example, with a reference value of 100 mg/dl, measured values of b Continue reading >>

Blood Sugar Level

Blood Sugar Level

The fluctuation of blood sugar (red) and the sugar-lowering hormone insulin (blue) in humans during the course of a day with three meals. One of the effects of a sugar-rich vs a starch-rich meal is highlighted.[1] The blood sugar level, blood sugar concentration, or blood glucose level is the amount of glucose present in the blood of humans and other animals. Glucose is a simple sugar and approximately 4 grams of glucose are present in the blood of humans at all times.[2] The body tightly regulates blood glucose levels as a part of metabolic homeostasis.[2] Glucose is stored in skeletal muscle and liver cells in the form of glycogen;[2] in fasted individuals, blood glucose is maintained at a constant level at the expense of glycogen stores in the liver and skeletal muscle.[2] In humans, glucose is the primary source of energy, and is critical for normal function, in a number of tissues,[2] particularly the human brain which consumes approximately 60% of blood glucose in fasted, sedentary individuals.[2] Glucose can be transported from the intestines or liver to other tissues in the body via the bloodstream.[2] Cellular glucose uptake is primarily regulated by insulin, a hormone produced in the pancreas.[2] Glucose levels are usually lowest in the morning, before the first meal of the day, and rise after meals for an hour or two by a few millimoles. Blood sugar levels outside the normal range may be an indicator of a medical condition. A persistently high level is referred to as hyperglycemia; low levels are referred to as hypoglycemia. Diabetes mellitus is characterized by persistent hyperglycemia from any of several causes, and is the most prominent disease related to failure of blood sugar regulation. There are different methods of testing and measuring blood sugar le Continue reading >>

Sources Of Error In Glucose Determinations In Neonatal Blood By Glucose Oxidase Methods, Including Dextrostix

Sources Of Error In Glucose Determinations In Neonatal Blood By Glucose Oxidase Methods, Including Dextrostix

Background. The definition, significance, and management of neonatal hypoglycaemia and the establishment of a safe, lower limit for blood glucose concentration in the newborn is still a matter of controversy. Methods. A review of the literature on neonatal hypoglycaemia is presented and guidelines for prevention and treatment discussed. Results. Healthy, full-term, appropriate for gestational age infants are thought to have a better tolerance for low blood glucose values during the first days of life than later in life. The infant's brain is capable of utilizing alternative energy substrates, such as ketone bodies and lactate. Intracerebral glycogen stores in the astrocytes and increased cerebral blood flow in response to hypoglycaemia maintain a sufficient substrate delivery. Infants at risk of developing neurological impairment following hypoglycaemia have a reduced capacity for mobilizing glucose from the glycogenolysis or gluconeogenesis and for utilizing alternative substrates for energy. Interpretation. There are no established lower limits defining neonatal hypoglycaemia of the healthy infant, but operational guidelines exist for prevention and intervention in infants at risk, for whom the blood glucose concentration should be maintained 2.6 mmol/l. Very few healthy, breastfed, term infants have blood glucose levels < 2 mmol/1. It is suggested that values down to 1.7 mmol/1 should be accepted as normal during the first day of life. Parenteral glucose should be administered to all infants with blood glucose levels < 1.4 mmol/1. The main goal is to prevent neonatal hypoglycaemia. Early and exclusive breastfeeding and the maintenance of normal body temperature are usually sufficient preventive measures in healthy infants. Microchip electrophoresis has recently attr Continue reading >>

Prime Pubmed | [sources Of Error In Enzymatic Determination Of Blood Glucose

Prime Pubmed | [sources Of Error In Enzymatic Determination Of Blood Glucose

Barthelmai, W. "[Sources of Error in Enzymatic Determination of Blood Glucose]." Monatsschrift Fur Kinderheilkunde, vol. 117, no. 4, 1969, pp. 264-7. Barthelmai W. [Sources of error in enzymatic determination of blood glucose]. Monatsschr Kinderheilkd. 1969;117(4):264-7. Barthelmai, W. (1969). [Sources of error in enzymatic determination of blood glucose]. Monatsschrift Fur Kinderheilkunde, 117(4), pp. 264-7. Barthelmai W. [Sources of Error in Enzymatic Determination of Blood Glucose]. Monatsschr Kinderheilkd. 1969;117(4):264-7. PubMed PMID: 5377525. * Article titles in AMA citation format should be in sentence-case TY - JOURT1 - [Sources of error in enzymatic determination of blood glucose].A1 - Barthelmai,W,PY - 1969/4/1/pubmedPY - 1969/4/1/medlinePY - 1969/4/1/entrezSP - 264EP - 7JF - Monatsschrift fur KinderheilkundeJO - Monatsschr KinderheilkdVL - 117IS - 4UR - - - PRIMEDP - Unbound MedicineER - Continue reading >>

The All Results Journals's Fan Box

The All Results Journals's Fan Box

4 sources of errors for monitoring glucose levels Diabetes is a very common pathology nowadays. Diabetic patients must control their blood glucose levels at least once a day, and this is where the problem starts. Blood glucose monitoring often includes important errors that affect patients and providers. This inaccuracy is due to strip, physical, patient, and pharmacological factors. 1. STRIP FACTORSThere is usually a strip-to-strip variation, which creates some imprecision in blood glucose readings. The size of strip can also result in error. In addition, changes in enzyme coverage, as well as changes in the proportion of the enzyme, influence accuracy. The reduction of the mediator can create problems with blood glucose strips. Blood glucose strips undertake complex biochemical reactions and have a limited lifetime (2 years approximately) and this fact is the reason why many strips fail. When a failure occurs, the brands underestimate or overestimate glucose levels. 2. PHYSICAL FACTORSThere are some physical factors that influence the accuracy of blood glucose strips. The most frequent are altitude and temperature. Figure 1 shows the effect of altitude when mountain climbers checked their blood glucose at 13,500 ft.As expected, the electrochemical glucose oxidase meters (One Touch Ultra and Precision X-tra) overestimate the glucose by 6% to 15%, whereas the glucose dehydrogenase meters (Ascensia Contour, AccuChek Complete, and Abbott Freestyle) were all within 5%. The influence of temperature is less predictable. Most meters have a temperature sensor and will report errors at extreme temperatures. The same mountain climbers also tested the influence of temperature, measuring glucose at 8 C (Figure 2). The results were brand specific, not technology dependent. The err Continue reading >>

Everything You Need To Know About Diabetes Test Strips

Everything You Need To Know About Diabetes Test Strips

Update: A lot of our readers ask us where can they find the best deals for test strips. We personally recommend Amazon. You can check the list of selections they offer by clicking here. Blood glucose test strips play a crucial role in helping you to monitor your daily blood glucose level and giving your doctor the data to adjust your medication to control your diabetes symptoms. Without the help from these little disposable strips, life with diabetes can become even more chaotic than ever. But what exactly are these thin little plastic slip and why are they so expensive? Are there any alternative method I can use? Where can I get the best deal on these test strips? This article will answer many of your questions and concerns regarding these blood glucose test strips: Table of Contents History on Glucose Test Strips How Does the Test Strips Work Why Are the Strips So Expensive? And Why the Price Discrepancy? Why Must Diabetic Patients Use Glucometer and Test Strip? How Often Should You Administer A Blood Glucose Test? How to Find Out if Your Glucose Monitor is Accurate? How Accurate Are the Test Strips? How to Find Out if Your Glucose Monitor is Accurate? What is a Urine Glucose Test? Can’t I Use This Procedure Instead? Expiration of Test Strips Medicare Plan B Coverage for Glucose Test Strips Where to Get the Best Deal on Test Strips? Ways to Save of Test Strips How to Avoid Counterfeit Blood Glucose Test Strips Can You Reuse Test Strips? Can You Make Your Own Test Strip? 4 Most Affordable Meters How to Pick the Right Glucometer? How to Dispose Used Test Strips, Lancets, and Needles? What to Do with All These Test Strip Containers? Selling Your Glucose Test Strips A Good Idea? Odd Way to Earn Some Money Back Questions? History on Glucose Test Strips The first glucomet Continue reading >>

Chapter 6 Flashcards | Quizlet

Chapter 6 Flashcards | Quizlet

maintain plasma glucose levels at a narrow range carbohydrates have four different properties size of the base chain. location of co function group. number of sugar units. stereochemistri carbohrates can be classify using four criteria the number of carbons in the chain. the size of the carbon chain carbs with active ketone or aldehyde functional group this property is used to identify glucose, fructose maltos galactose and lactose the ketone or aldehyde group is used to form glycosidic bonds- sucrose for example have the same order and types of bonds but different spatial arrangement and different properties is a six carbon aldohexose with the glucose chemical formula are formed by interactions of two monosaccharides with the loss of a water molecule three of the most common disaccharides are maltose two glucose unite lactose glucose and galatose ; sucrose glucose and frctose are a group of complex carbohydrates composed of more than 20 monosaccharides and are usually insouble inwater starch glycogen and cellulose which contain 25-500 gluctose units salivary amylase. pancreatic amylase disccharides. portal circulation . liver glucose reacts with ATP in the presence of to form glucose-6-phosphate results in the glycolysis of glucose to pyruate or lactate and can occur with out oxygen is an imporant energy source to prevent cell damage from oxidation and freee radicals conversion of glucose to glycogen for storge formation of glucose from noncarbohydrate source such as anoino acids glycerol or lactate is the most impornt hormone because it is the only hormone the lowers blood glucose leves when they re to high liver pancreas and other endocrine glands contropl blood glucose during a beief fast a dop in glucose is avoided by formation f glucose via secred by the beta cel Continue reading >>

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