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Randie R Little - One of the best experts on this subject based on the ideXlab platform.
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glycated hemoglobin standardization national Glycohemoglobin standardization program ngsp perspective
Clinical Chemistry and Laboratory Medicine, 2003Co-Authors: Randie R LittleAbstract:The Diabetes Control and Complications Trial (DCCT) and the United Kingdom Prospective Diabetes Study (UKPDS) demonstrated conclusively that risks for complications in patients with diabetes are directly related to glycemic control, as measured by glycated hemoglobin (GHb). Many diabetes organizations worldwide now recommend GHb targets in terms of DCCT/ UKPDS hemoglobin A 1c (HbA 1c ). However, in 1993 there was a lack of comparability of GHb test results among methods and laboratories that represented a major obstacle to meaningful implementation of specific guidelines for diabetes care. The National Glycohemoglobin Standardization Program (NGSP) was implemented to enable laboratories to report DCCT/UKPDS-traceable GHb/HbA 1c results. The number of methods and laboratories certified by the NGSP as traceable to the DCCT has steadily increased. Proficiency testing results show marked improvement in the comparability of GHb results. By the end of 2002, 98% of surveyed laboratories (n = approx. 2000) reported GHb results as HbA 1c or equivalent compared to 50% in 1993. Ninety-seven percent of laboratories used an NGSP-certified method. For most certified methods in 2002, between-laboratory CVs were <5%. For all certified methods in 2002, the mean HbA 1c value (%) was within 0.8% HbA 1c from the NGSP target at all HbA 1c concentrations. The vast majority of laboratories in the US are now reporting results that are traceable to DCCT/UKPDS outcomes.
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Glycated hemoglobin standardization--National Glycohemoglobin Standardization Program (NGSP) perspective.
Clinical Chemistry and Laboratory Medicine, 2003Co-Authors: Randie R LittleAbstract:The Diabetes Control and Complications Trial (DCCT) and the United Kingdom Prospective Diabetes Study (UKPDS) demonstrated conclusively that risks for complications in patients with diabetes are directly related to glycemic control, as measured by glycated hemoglobin (GHb). Many diabetes organizations worldwide now recommend GHb targets in terms of DCCT/ UKPDS hemoglobin A 1c (HbA 1c ). However, in 1993 there was a lack of comparability of GHb test results among methods and laboratories that represented a major obstacle to meaningful implementation of specific guidelines for diabetes care. The National Glycohemoglobin Standardization Program (NGSP) was implemented to enable laboratories to report DCCT/UKPDS-traceable GHb/HbA 1c results. The number of methods and laboratories certified by the NGSP as traceable to the DCCT has steadily increased. Proficiency testing results show marked improvement in the comparability of GHb results. By the end of 2002, 98% of surveyed laboratories (n = approx. 2000) reported GHb results as HbA 1c or equivalent compared to 50% in 1993. Ninety-seven percent of laboratories used an NGSP-certified method. For most certified methods in 2002, between-laboratory CVs were
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biological variation of Glycohemoglobin
Clinical Chemistry, 2002Co-Authors: Curt L Rohlfing, Randie R Little, Hsiaomei Wiedmeyer, J D England, Lee V Grotz, Alethea L Tennill, Richard W Madsen, David E GoldsteinAbstract:Glycohemoglobin (GHb) is a measure of long-term mean glycemia that predicts risks for the development and/or progression of diabetic complications in patients with type 1 and type 2 diabetes (1)(2). Several reports have suggested, however, that although the within-subject variation in GHb unrelated to glycemia is minimal, there is substantial between-subject variation in GHb, e.g., “low glycators” and “high glycators” (3)(4)(5). These reports have suggested that because of this large between-subject variation, GHb may not be useful for diabetes screening or diagnosis and that when GHb is used for routine management of patients with diabetes, different patients may require very different GHb target values to achieve the same overall glycemic status. We therefore examined the biological variation of GHb and fasting plasma glucose (FPG) in nondiabetic individuals. Individuals without diabetes (n = 48) participated in a study of an artificial sweetener that has no effect on GHb or plasma glucose concentrations [Submission to Food and Drug Administration. McNeil Specialty Products Company food additive petition 7A3987 (Sucralose), 1987–1997]. Because the study was designed to detect minimal changes in plasma glucose concentrations, all participants were men to avoid the effects of cyclic hormonal changes on insulin (and therefore, plasma glucose) concentrations. At the prestudy screening, all individuals were healthy on the basis of a medical history, physical examination, and electrocardiography results; results of hematology and blood chemistry studies, urine examination, and measures of blood …
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The National Glycohemoglobin Standardization Program: A Five-Year Progress Report
Clinical Chemistry, 2001Co-Authors: Randie R Little, Hsiaomei Wiedmeyer, Curt L Rohlfing, Gary L. Myers, David B. Sacks, David E GoldsteinAbstract:Background: The Diabetes Control and Complications Trial (DCCT) and the United Kingdom Prospective Diabetes Study (UKPDS) demonstrated conclusively that risks for complications in patients with diabetes are directly related to glycemic control, as measured by Glycohemoglobin (GHB). In 1994, one year after the DCCT results were reported, the American Diabetes Association (ADA) set specific diabetes treatment goals. However, 1993 College of American Pathologists (CAP) Survey results indicated a lack of comparability of GHB test results among methods and laboratories that represented a major obstacle to meaningful implementation of the ADA guidelines. Thus, an AACC subcommittee was formed in 1993 to develop a standardization program that would enable laboratories to report DCCT-traceable GHB results. This program was implemented in 1996 by the National Glycohemoglobin Standardization Program (NGSP) Steering Committee. Approach: We review the NGSP process and summarize progress in standardization through analysis of CAP data. Content: Since 1996, the number of methods and laboratories certified by the NGSP as traceable to the DCCT has steadily increased. CAP GH2-B survey results reported in December 2000 show marked improvement over 1993 data in the comparability of GHB results. In 2000, 90% of surveyed laboratories reported GHB results as hemoglobin A1c (HbA1c) or equivalent, compared with 50% in 1993. Of laboratories reporting HbA1c in 2000, 78% used a NGSP-certified method. For most certified methods in 2000, between-laboratory CVs were
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the national Glycohemoglobin standardization program a five year progress report
Clinical Chemistry, 2001Co-Authors: Randie R Little, Hsiaomei Wiedmeyer, Curt L Rohlfing, Gary L. Myers, David B. Sacks, David E GoldsteinAbstract:Background: The Diabetes Control and Complications Trial (DCCT) and the United Kingdom Prospective Diabetes Study (UKPDS) demonstrated conclusively that risks for complications in patients with diabetes are directly related to glycemic control, as measured by Glycohemoglobin (GHB). In 1994, one year after the DCCT results were reported, the American Diabetes Association (ADA) set specific diabetes treatment goals. However, 1993 College of American Pathologists (CAP) Survey results indicated a lack of comparability of GHB test results among methods and laboratories that represented a major obstacle to meaningful implementation of the ADA guidelines. Thus, an AACC subcommittee was formed in 1993 to develop a standardization program that would enable laboratories to report DCCT-traceable GHB results. This program was implemented in 1996 by the National Glycohemoglobin Standardization Program (NGSP) Steering Committee. Approach: We review the NGSP process and summarize progress in standardization through analysis of CAP data. Content: Since 1996, the number of methods and laboratories certified by the NGSP as traceable to the DCCT has steadily increased. CAP GH2-B survey results reported in December 2000 show marked improvement over 1993 data in the comparability of GHB results. In 2000, 90% of surveyed laboratories reported GHB results as hemoglobin A1c (HbA1c) or equivalent, compared with 50% in 1993. Of laboratories reporting HbA1c in 2000, 78% used a NGSP-certified method. For most certified methods in 2000, between-laboratory CVs were <5%. For all certified methods in 2000, the mean percent HbA1c was within 0.8% HbA1c of the NGSP target at all HbA1c concentrations. Summary: The majority of laboratories in the US are now reporting results that are traceable to DCCT/UKPDS outcomes.
David E Goldstein - One of the best experts on this subject based on the ideXlab platform.
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biological variation of Glycohemoglobin
Clinical Chemistry, 2002Co-Authors: Curt L Rohlfing, Randie R Little, Hsiaomei Wiedmeyer, J D England, Lee V Grotz, Alethea L Tennill, Richard W Madsen, David E GoldsteinAbstract:Glycohemoglobin (GHb) is a measure of long-term mean glycemia that predicts risks for the development and/or progression of diabetic complications in patients with type 1 and type 2 diabetes (1)(2). Several reports have suggested, however, that although the within-subject variation in GHb unrelated to glycemia is minimal, there is substantial between-subject variation in GHb, e.g., “low glycators” and “high glycators” (3)(4)(5). These reports have suggested that because of this large between-subject variation, GHb may not be useful for diabetes screening or diagnosis and that when GHb is used for routine management of patients with diabetes, different patients may require very different GHb target values to achieve the same overall glycemic status. We therefore examined the biological variation of GHb and fasting plasma glucose (FPG) in nondiabetic individuals. Individuals without diabetes (n = 48) participated in a study of an artificial sweetener that has no effect on GHb or plasma glucose concentrations [Submission to Food and Drug Administration. McNeil Specialty Products Company food additive petition 7A3987 (Sucralose), 1987–1997]. Because the study was designed to detect minimal changes in plasma glucose concentrations, all participants were men to avoid the effects of cyclic hormonal changes on insulin (and therefore, plasma glucose) concentrations. At the prestudy screening, all individuals were healthy on the basis of a medical history, physical examination, and electrocardiography results; results of hematology and blood chemistry studies, urine examination, and measures of blood …
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The National Glycohemoglobin Standardization Program: A Five-Year Progress Report
Clinical Chemistry, 2001Co-Authors: Randie R Little, Hsiaomei Wiedmeyer, Curt L Rohlfing, Gary L. Myers, David B. Sacks, David E GoldsteinAbstract:Background: The Diabetes Control and Complications Trial (DCCT) and the United Kingdom Prospective Diabetes Study (UKPDS) demonstrated conclusively that risks for complications in patients with diabetes are directly related to glycemic control, as measured by Glycohemoglobin (GHB). In 1994, one year after the DCCT results were reported, the American Diabetes Association (ADA) set specific diabetes treatment goals. However, 1993 College of American Pathologists (CAP) Survey results indicated a lack of comparability of GHB test results among methods and laboratories that represented a major obstacle to meaningful implementation of the ADA guidelines. Thus, an AACC subcommittee was formed in 1993 to develop a standardization program that would enable laboratories to report DCCT-traceable GHB results. This program was implemented in 1996 by the National Glycohemoglobin Standardization Program (NGSP) Steering Committee. Approach: We review the NGSP process and summarize progress in standardization through analysis of CAP data. Content: Since 1996, the number of methods and laboratories certified by the NGSP as traceable to the DCCT has steadily increased. CAP GH2-B survey results reported in December 2000 show marked improvement over 1993 data in the comparability of GHB results. In 2000, 90% of surveyed laboratories reported GHB results as hemoglobin A1c (HbA1c) or equivalent, compared with 50% in 1993. Of laboratories reporting HbA1c in 2000, 78% used a NGSP-certified method. For most certified methods in 2000, between-laboratory CVs were
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the national Glycohemoglobin standardization program a five year progress report
Clinical Chemistry, 2001Co-Authors: Randie R Little, Hsiaomei Wiedmeyer, Curt L Rohlfing, Gary L. Myers, David B. Sacks, David E GoldsteinAbstract:Background: The Diabetes Control and Complications Trial (DCCT) and the United Kingdom Prospective Diabetes Study (UKPDS) demonstrated conclusively that risks for complications in patients with diabetes are directly related to glycemic control, as measured by Glycohemoglobin (GHB). In 1994, one year after the DCCT results were reported, the American Diabetes Association (ADA) set specific diabetes treatment goals. However, 1993 College of American Pathologists (CAP) Survey results indicated a lack of comparability of GHB test results among methods and laboratories that represented a major obstacle to meaningful implementation of the ADA guidelines. Thus, an AACC subcommittee was formed in 1993 to develop a standardization program that would enable laboratories to report DCCT-traceable GHB results. This program was implemented in 1996 by the National Glycohemoglobin Standardization Program (NGSP) Steering Committee. Approach: We review the NGSP process and summarize progress in standardization through analysis of CAP data. Content: Since 1996, the number of methods and laboratories certified by the NGSP as traceable to the DCCT has steadily increased. CAP GH2-B survey results reported in December 2000 show marked improvement over 1993 data in the comparability of GHB results. In 2000, 90% of surveyed laboratories reported GHB results as hemoglobin A1c (HbA1c) or equivalent, compared with 50% in 1993. Of laboratories reporting HbA1c in 2000, 78% used a NGSP-certified method. For most certified methods in 2000, between-laboratory CVs were <5%. For all certified methods in 2000, the mean percent HbA1c was within 0.8% HbA1c of the NGSP target at all HbA1c concentrations. Summary: The majority of laboratories in the US are now reporting results that are traceable to DCCT/UKPDS outcomes.
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is Glycohemoglobin testing useful in diabetes mellitus lessons from the diabetes control and complications trial
Clinical Chemistry, 1994Co-Authors: David E Goldstein, Randie R Little, Hsiaomei Wiedmeyer, J D England, Curt L Rohlfing, A L WilkeAbstract:To address the question, Do laboratory tests cost money or save money? we have used as a model for discussion a common chronic disease, diabetes mellitus, and a widely used laboratory test, that for Glycohemoglobin, a measure of long-term glycemia used to manage diabetic patients. Diabetes mellitus is serious, highly prevalent, and costly. In 1992, $1 of every $7 spent on health in the US was for diabetes, predominantly for treatment of the chronic complications of the disease. The recently completed Diabetes Control and Complications Trial (DCCT) demonstrated that development and progression of the chronic complications of diabetes are related to the degree of altered glycemia as quantified by determinations of Glycohemoglobin. Thus, use of Glycohemoglobin testing for routine diabetes care provides an objective measure of a patient's risk for developing diabetic complications. Results of this test can alert patients and health providers to the need for change in the treatment plan. Optimal use of Glycohemoglobin testing for diabetes care will require standardization of test results.
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more than you ever wanted to know but need to know about Glycohemoglobin testing
Diabetes Care, 1994Co-Authors: David E Goldstein, Randie R LittleAbstract:In this issue of Diabetes Care , Koskinen et al. report that fetal hemoglobin levels are increased in diabetic patients (this issue, L.K. Koskinen et al., p. 828–831). The study design was a cross-sectional one with Glycohemoglobin and fetal hemoglobin determinations for 930 diabetic and 258 control subjects. The authors found thatalmost 7% of the diabetic subjects had fetal hemoglobin levels >1% compared with only∼2% of the control subjects. Furthermore, fetal hemoglobin levels were increased moreoften in those with IDDM than in those with NIDDM.
Erling Sundrehagen - One of the best experts on this subject based on the ideXlab platform.
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Glycohemoglobin filter assay for doctors’ offices based on boronic acid affinity principle
Clinical Chemistry, 1997Co-Authors: Frank Frantzen, Kjersti Grimsrud, Dagerik Heggli, Arne Ludvig Faaren, Trond Lovli, Erling SundrehagenAbstract:We present a new filter assay for the determination of Glycohemoglobin as a unique application of the boronic acid affinity principle. With the use of a water-soluble blue-colored boronic acid derivative and a specific precipitation method for hemoglobin, total hemoglobin including bound boronic acid is precipitated and collected on a filter strip before quantification. Hemoglobin and boronic acid are quantified by a dual-wavelength reflectometric measurement, and the result is reported directly as percent Glycohemoglobin. The test is simple, quick, and designed as a doctors’ office test for the monitoring and management of diabetes. The imprecision of the assay is
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Glycohemoglobin filter assay for doctors offices based on boronic acid affinity principle
Clinical Chemistry, 1997Co-Authors: Frank Frantzen, Kjersti Grimsrud, Dagerik Heggli, Arne Ludvig Faaren, Trond Lovli, Erling SundrehagenAbstract:We present a new filter assay for the determination of Glycohemoglobin as a unique application of the boronic acid affinity principle. With the use of a water-soluble blue-colored boronic acid derivative and a specific precipitation method for hemoglobin, total hemoglobin including bound boronic acid is precipitated and collected on a filter strip before quantification. Hemoglobin and boronic acid are quantified by a dual-wavelength reflectometric measurement, and the result is reported directly as percent Glycohemoglobin. The test is simple, quick, and designed as a doctors’ office test for the monitoring and management of diabetes. The imprecision of the assay is <4% over the range 3–18% Hb A1c, and the method is linear up to at least 20% Hb A1c. Comparisons with four well-established Glycohemoglobin methods yielded correlation coefficients ranging from 0.94 to 0.99, with slopes from 0.94 to 1.01.
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soluble highly coloured phenylboronic acids and their use in Glycohemoglobin quantification
Clinica Chimica Acta, 1997Co-Authors: Frank Frantzen, Kjersti Grimsrud, Dagerik Heggli, Erling SundrehagenAbstract:Water soluble dye-phenylboronic acid conjugates (dye-PBAs) possessing strong absorption of visible light are introduced as new reagents for the determination of Glycohemoglobin. Their functionality and prospective use are demonstrated in a semi-homogenous Glycohemoglobin assay. The assay is based on cis-diol esterification of dye-PBA to Glycohemoglobin followed by selective precipitation of hemoglobin from solution, co-precipitating bound dye-PBA. Quantification of the molar “dye-PBA/Hb”-ratio in redissolved precipitates using either absorption or fluorescence spectroscopy, reflects the glycation level of the blood samples used. Future development of the assay principle is illustrated in a filter based assay, collecting the precipitated hemoglobin on a filter followed by reflectometric readings directly on the precipitate. The significance of this work lies first, in the demonstration of a new principle for the determination of Glycohemoglobin, and second, as an illustration of the prospective use of water soluble, signal-forming non-immobilised boronic acids in the determination of cis-diol containing analytes.
Curt L Rohlfing - One of the best experts on this subject based on the ideXlab platform.
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biological variation of Glycohemoglobin
Clinical Chemistry, 2002Co-Authors: Curt L Rohlfing, Randie R Little, Hsiaomei Wiedmeyer, J D England, Lee V Grotz, Alethea L Tennill, Richard W Madsen, David E GoldsteinAbstract:Glycohemoglobin (GHb) is a measure of long-term mean glycemia that predicts risks for the development and/or progression of diabetic complications in patients with type 1 and type 2 diabetes (1)(2). Several reports have suggested, however, that although the within-subject variation in GHb unrelated to glycemia is minimal, there is substantial between-subject variation in GHb, e.g., “low glycators” and “high glycators” (3)(4)(5). These reports have suggested that because of this large between-subject variation, GHb may not be useful for diabetes screening or diagnosis and that when GHb is used for routine management of patients with diabetes, different patients may require very different GHb target values to achieve the same overall glycemic status. We therefore examined the biological variation of GHb and fasting plasma glucose (FPG) in nondiabetic individuals. Individuals without diabetes (n = 48) participated in a study of an artificial sweetener that has no effect on GHb or plasma glucose concentrations [Submission to Food and Drug Administration. McNeil Specialty Products Company food additive petition 7A3987 (Sucralose), 1987–1997]. Because the study was designed to detect minimal changes in plasma glucose concentrations, all participants were men to avoid the effects of cyclic hormonal changes on insulin (and therefore, plasma glucose) concentrations. At the prestudy screening, all individuals were healthy on the basis of a medical history, physical examination, and electrocardiography results; results of hematology and blood chemistry studies, urine examination, and measures of blood …
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The National Glycohemoglobin Standardization Program: A Five-Year Progress Report
Clinical Chemistry, 2001Co-Authors: Randie R Little, Hsiaomei Wiedmeyer, Curt L Rohlfing, Gary L. Myers, David B. Sacks, David E GoldsteinAbstract:Background: The Diabetes Control and Complications Trial (DCCT) and the United Kingdom Prospective Diabetes Study (UKPDS) demonstrated conclusively that risks for complications in patients with diabetes are directly related to glycemic control, as measured by Glycohemoglobin (GHB). In 1994, one year after the DCCT results were reported, the American Diabetes Association (ADA) set specific diabetes treatment goals. However, 1993 College of American Pathologists (CAP) Survey results indicated a lack of comparability of GHB test results among methods and laboratories that represented a major obstacle to meaningful implementation of the ADA guidelines. Thus, an AACC subcommittee was formed in 1993 to develop a standardization program that would enable laboratories to report DCCT-traceable GHB results. This program was implemented in 1996 by the National Glycohemoglobin Standardization Program (NGSP) Steering Committee. Approach: We review the NGSP process and summarize progress in standardization through analysis of CAP data. Content: Since 1996, the number of methods and laboratories certified by the NGSP as traceable to the DCCT has steadily increased. CAP GH2-B survey results reported in December 2000 show marked improvement over 1993 data in the comparability of GHB results. In 2000, 90% of surveyed laboratories reported GHB results as hemoglobin A1c (HbA1c) or equivalent, compared with 50% in 1993. Of laboratories reporting HbA1c in 2000, 78% used a NGSP-certified method. For most certified methods in 2000, between-laboratory CVs were
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the national Glycohemoglobin standardization program a five year progress report
Clinical Chemistry, 2001Co-Authors: Randie R Little, Hsiaomei Wiedmeyer, Curt L Rohlfing, Gary L. Myers, David B. Sacks, David E GoldsteinAbstract:Background: The Diabetes Control and Complications Trial (DCCT) and the United Kingdom Prospective Diabetes Study (UKPDS) demonstrated conclusively that risks for complications in patients with diabetes are directly related to glycemic control, as measured by Glycohemoglobin (GHB). In 1994, one year after the DCCT results were reported, the American Diabetes Association (ADA) set specific diabetes treatment goals. However, 1993 College of American Pathologists (CAP) Survey results indicated a lack of comparability of GHB test results among methods and laboratories that represented a major obstacle to meaningful implementation of the ADA guidelines. Thus, an AACC subcommittee was formed in 1993 to develop a standardization program that would enable laboratories to report DCCT-traceable GHB results. This program was implemented in 1996 by the National Glycohemoglobin Standardization Program (NGSP) Steering Committee. Approach: We review the NGSP process and summarize progress in standardization through analysis of CAP data. Content: Since 1996, the number of methods and laboratories certified by the NGSP as traceable to the DCCT has steadily increased. CAP GH2-B survey results reported in December 2000 show marked improvement over 1993 data in the comparability of GHB results. In 2000, 90% of surveyed laboratories reported GHB results as hemoglobin A1c (HbA1c) or equivalent, compared with 50% in 1993. Of laboratories reporting HbA1c in 2000, 78% used a NGSP-certified method. For most certified methods in 2000, between-laboratory CVs were <5%. For all certified methods in 2000, the mean percent HbA1c was within 0.8% HbA1c of the NGSP target at all HbA1c concentrations. Summary: The majority of laboratories in the US are now reporting results that are traceable to DCCT/UKPDS outcomes.
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is Glycohemoglobin testing useful in diabetes mellitus lessons from the diabetes control and complications trial
Clinical Chemistry, 1994Co-Authors: David E Goldstein, Randie R Little, Hsiaomei Wiedmeyer, J D England, Curt L Rohlfing, A L WilkeAbstract:To address the question, Do laboratory tests cost money or save money? we have used as a model for discussion a common chronic disease, diabetes mellitus, and a widely used laboratory test, that for Glycohemoglobin, a measure of long-term glycemia used to manage diabetic patients. Diabetes mellitus is serious, highly prevalent, and costly. In 1992, $1 of every $7 spent on health in the US was for diabetes, predominantly for treatment of the chronic complications of the disease. The recently completed Diabetes Control and Complications Trial (DCCT) demonstrated that development and progression of the chronic complications of diabetes are related to the degree of altered glycemia as quantified by determinations of Glycohemoglobin. Thus, use of Glycohemoglobin testing for routine diabetes care provides an objective measure of a patient's risk for developing diabetic complications. Results of this test can alert patients and health providers to the need for change in the treatment plan. Optimal use of Glycohemoglobin testing for diabetes care will require standardization of test results.
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Interlaboratory standardization of measurements of Glycohemoglobins.
Clinical Chemistry, 1992Co-Authors: Randie R Little, Hsiaomei Wiedmeyer, J D England, Curt L Rohlfing, A L Wilke, F H Wians, J M Jacobson, V Zellmer, David E GoldsteinAbstract:The diversity of methods used to measure Glycohemoglobins (GHb) makes it difficult to compare patients' results among laboratories. We reported previously the feasibility of providing comparable results from different assays by use of common calibrators. We here compare results from seven different GHb methods calibrated by use of hemolysates assayed by a precise ion-exchange high-performance liquid-chromatographic (HPLC) method for hemoglobin A1c (HbA1c). Thus, regardless of the GHb species measured by the seven methods, results were referenced to the HbA1c content of the calibrators. Without this calibration, GHb values for single samples varied, e.g., from 4.0% to 8.1% and from 10% to 14.2% in the normal and high ranges, respectively. Calibration decreased between-method variability (single sample ranges of, e.g., 4.8% to 5.4% and 9.4% to 10.2% in the normal and high ranges, respectively) and improved interassay precision. We conclude that this approach to calibration of GHb measurements allows direct comparison of results obtained by different methods and improves precision.
William L Roberts - One of the best experts on this subject based on the ideXlab platform.
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effects of hemoglobin c and s traits on eight Glycohemoglobin methods
Clinical Chemistry, 2000Co-Authors: William L Roberts, Barun K De, Diane Brown, Michael C Hanbury, James D Hoyer, Garry W John, Thomas L Lambert, Ryan B Lundell, Curt Rohlfing, Randie R LittleAbstract:Glycohemoglobin (gHb) is a marker of long-term glycemic control that has been shown to correlate with complications of diabetes mellitus (1). The National Glycohemoglobin Standardization Program (NGSP) was established to standardize gHb results so that clinical laboratory results are comparable to those reported by the Diabetes Control and Complications Trial (2)(3). Previous studies have shown that some gHb methods yield inaccurate results with samples heterozygous for hemoglobin (Hb) C or Hb S (4)(5)(6). At least 10% of black Americans have either Hb C or S trait, and there were 19 million black Americans over age 19 in 1990 (7)(8)(9)(10). The prevalence of diabetes is estimated to be 5.1% of the adult population, with the rate for non-Hispanic blacks being 1.6-fold higher than that of non-Hispanic whites (11). It is therefore probable that at least 150 000 Americans with diabetes have Hb C or S trait. Here, we investigate the measurement of gHb in specimens containing Hb C or S trait using eight gHb methods currently in clinical use. Whole blood samples from individuals homozygous for Hb A (n = 43) and heterozygous for Hb C or S (n = 43 and 61, respectively) were collected in EDTA tubes. Hb variants were identified by their characteristic Variant A1c HPLC chromatograms (Bio-Rad Laboratories). Aliquots of these samples containing between 4% and 14% Hb A1c (NGSP Hb A1c evaluation range) were stored refrigerated (2–8 °C) and analyzed within 10 days of collection. This study was approved by the Institutional Review Board of the University of Utah. The CLC 330 gHb analyzer (Primus Corporation) was operated at the University of Missouri. This method was chosen as the comparison method for this study because results from boronate affinity chromatography should not …
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effects of nine hemoglobin variants on five Glycohemoglobin methods
Clinical Chemistry, 2000Co-Authors: William L Roberts, Elizabeth L Frank, Linda Moulton, Christine Papadea, Jimmie K Noffsinger, Chingnan OuAbstract:Most studies of the effects of variant hemoglobins (Hbs) on specific Glycohemoglobin (gHb) methods have been case reports of a single variant Hb and one or two analytical methods (1)(2)(3)(4). Few studies have systematically examined multiple Hb variants with several widely used analytical methods. In this report, we describe the effects of nine heterozygous Hb variants on five gHb methods. A boronate affinity method was chosen as the comparative method because it has high specificity for glycated Hb and negligible interference by variant Hbs (5). Over 10 months, we studied 40 samples with nine variant Hbs; 38 were detected during routine gHb analysis by a cation-exchange method. Two samples (Hb E trait) were identified during routine Hb phenotype analysis. Samples were stored at 2–8 °C until analysis within 10 days of collection. Cation-exchange chromatography was performed on a Variant system with the Hb A1c program (Bio-Rad Laboratories) and on an A1c 2.2 Plus analyzer using a 3-min protocol (Tosoh Medics). Immunoassays were performed on a DCA 2000 (Bayer Corporation, Elkhart, IN) and on a Hitachi 717 with Tina-quant HbA1c II reagents (Roche Diagnostics, Indianapolis, IN). Boronate affinity analysis on a CLC 385 analyzer (Primus Corporation) served as the comparative method. All methods used the manufacturers’ reagents as recommended, had imprecision (CV) <5%, are certified traceable to the Diabetes Control and Complications Trial by the National Glycohemoglobin Standardization Program, and reported results as percentage of Hb A1c. Hb phenotype analysis was performed on all samples using a PVS99 system (Primus). This HPLC system uses a poly-aspartic acid cation-exchange column and a complex nonlinear salt and pH gradient at 40 °C. Rare phenotypes, including Grady, Hope, and Raleigh were identified using a poly-aspartic acid column with a nonlinear salt and pH gradient …
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Effects of Nine Hemoglobin Variants on Five Glycohemoglobin Methods
Clinical Chemistry, 2000Co-Authors: William L Roberts, Elizabeth L Frank, Linda Moulton, Christine Papadea, Jimmie K Noffsinger, Chingnan OuAbstract:Most studies of the effects of variant hemoglobins (Hbs) on specific Glycohemoglobin (gHb) methods have been case reports of a single variant Hb and one or two analytical methods (1)(2)(3)(4). Few studies have systematically examined multiple Hb variants with several widely used analytical methods. In this report, we describe the effects of nine heterozygous Hb variants on five gHb methods. A boronate affinity method was chosen as the comparative method because it has high specificity for glycated Hb and negligible interference by variant Hbs (5). Over 10 months, we studied 40 samples with nine variant Hbs; 38 were detected during routine gHb analysis by a cation-exchange method. Two samples (Hb E trait) were identified during routine Hb phenotype analysis. Samples were stored at 2–8 °C until analysis within 10 days of collection. Cation-exchange chromatography was performed on a Variant system with the Hb A1c program (Bio-Rad Laboratories) and on an A1c 2.2 Plus analyzer using a 3-min protocol (Tosoh Medics). Immunoassays were performed on a DCA 2000 (Bayer Corporation, Elkhart, IN) and on a Hitachi 717 with Tina-quant HbA1c II reagents (Roche Diagnostics, Indianapolis, IN). Boronate affinity analysis on a CLC 385 analyzer (Primus Corporation) served as the comparative method. All methods used the manufacturers’ reagents as recommended, had imprecision (CV)
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Glycohemoglobin results in samples with hemoglobin c or s trait a comparison of four test systems
Clinical Chemistry, 1999Co-Authors: William L Roberts, Janelle M Chiasera, Kory M WardcookAbstract:A wide variety of commercial methods are available to measure Glycohemoglobin (gHb). These methods measure various species of gHb, e.g., total gHb, hemoglobin A1 (Hb A1), or Hb A1c. Some methods are based on charge differences between glycated and nonglycated hemoglobins (e.g., cation-exchange chromatography, electrophoresis, and isoelectric focusing), whereas boronate affinity methods depend upon the binding of the sugar groups on the hemoglobin molecule (1). Immunoassay of Hb A1c depends on the presence of an epitope that includes glucose and N-terminal amino acids of the β chain of hemoglobin. These methods usually measure Hb A1c as a percentage of total hemoglobin. Some immunoassay methods also measure Hb S1c or Hb C1c, whereas others do not (2). The National Glycohemoglobin Standardization Program (NGSP) was established to certify the various commercial methods so that they can be related to the candidate reference method used in the Diabetes Control and Complications Trial (DCCT) (3)(4). Recently, the effects of Hb AC and Hb AS on one gHb immunoassay method were assessed (5). Samples containing Hb C trait showed modestly higher results than the HPLC method used. Although hemoglobin variants are relatively rare in Caucasians of northern European descent, the African-American population has an 8% prevalence of Hb AS and a 3% prevalence of Hb AC (6)(7). In this study, we describe the influence of Hb AS and Hb AC on four DCCT-traceable gHb methods. A total of 129 samples were collected in evacuated tubes containing EDTA as an anticoagulant. Samples with hemoglobin variants were identified by comparison of retention times on the Diamat system (Bio-Rad Clinical Laboratories) to known retention times for Hb S and Hb C. Of the 129 samples collected, 47 were homozygous for Hb A, 39 were …