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HbA1c (Hemoglobin A1c)

Analyte: Hemoglobin A1c

Specimen Type: EDTA Whole Blood, Inquire for additional option(s)

Optimum Volume: 0.5 mL

Stability:

2-8°C -20°C -70°C
1 week 6 months 1 year

Reporting units: %

Method: Immunoturbidimetric

Biological or Clinical Significance:

Hemoglobin A1c is produced by nonenzymatic glycosylation of the terminal amino group (valine) of the β chain in hemoglobin. Since the reaction is controlled by mass action and the red cell is permeable to glucose, the quantity of HbA1c formed is directly proportional to the average plasma glucose concentration during the red cell’s 120-day life span. As a consequence of this process, HbA1c constitutes a higher percentage (4-5%) of total hemoglobin in long-term hyperglycemia when compared to normoglycemia.

Principle of Test Method:

The HbA1c assay is an automated immunoturbidimetric method.

References:

1. The National Academy of Clinical Biochemistry: Laboratory Medicine Practice Guidelines, Guidelines and recommendations for Laboratory analysis in the diagnosis and management of diabetes mellitus, 2002.
2. Sacks DB, Arnold M, Bakris GL, Bruns DE, Horvath AR, Kirkman MS, Lernmark A, Metzger BE, Nathan DM. Guidelines and recommendations for Laboratory analysis in the diagnosis and management of diabetes mellitus, The National Academy of Clinical Biochemistry: Laboratory Medicine Practice Guidelines (draft version) 2007.
3. Little RR, Rohlfing CL, Tennill AL, Connolly S, Hanson S. Effects of sample storage conditions on glycated hemoglobin measurement: Evaluation of five different high performance liquid chromatography methods. Diabetes Technol Ther. 2007; 9:36–42.
4. Selvin E, Coresh J, Jordahl J, Boland L, Steffes MW. Stability of haemoglobin A1c (HbA1c) measurements from frozen whole blood samples stored for over a decade. Diabet Med. 2005; 22:1726–1730.
5. Goldstein DE, Little RR, Lorenz RA, Malone JI, Nathan D, Peterson CM. Tests of glycemia in diabetes. Diabetes Care. 1995; 18:896–909.
6. Rohlfing CL, Wiedmeyer HM, Little RR, England JD, Tennill A, Goldstein DE. Defining the relationship between plasma glucose and HbA1c in the Diabetes Control and Complications Trial. Diabetes Care 2002; 25:275–278.
7. The Diabetes Control and Complications Trial Research Group. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin- dependent diabetes mellitus. N Engl J Med. 1993; 329:977–986.
8. UK Prospective Diabetes Study (UKPDS) group. Intensive blood glucose control with sulfonylureas or insulin compared with conventional treatment and risk of complications in patients with type 2 diabetes (UKPDS 33). Lancet 1998; 352:837–853.
9. Goldstein DE, Little RR, Wiedmeyer HM, England JD, McKenzie EM. Glycated hemoglobin: methodologies and clinical applications. Clin Chem 1986; 32:B64–B70.
10. Karl J et al. Development and standardization of a new immunoturbidimetric HbA1c assay. Klin Lab 1993;39:991–996.
11. Chang J, Hoke C, Ettinger B, Penerian G. Evaluation and interference study of hemoglobin A1c measures by turbidimetric inhibition immunoassay. Am J Clin Pathol 1998; 109(3):274–278.
12. Frank EL, Moulton L, Little RR, Wiedemeyer HM, Rohlfing C, Roberts WL. Effect of hemoglobin C and S traits on seven glycohemoglobin methods. Clin Chem 2000; 46(6):864–866.
13. Email from Yuanfang Deng, Siemens, to Caicai Wu. August 15, 2008.
14. Rifai N. Implementation of standardization of hemoglobin A1c measurement. Clin Chem. 2008;
15. Jeppsson JO, Kobold U, Barr J, Finke A, Hoelzel W, Hoshino T, Miedema K, Mosca A, Mauri P, Paroni R, Thienpont L, Umemoto M, and Weykamp C. Approved IFCC reference method for the measurement of HbA1c in human blood. Clin Chem Lab Med. 2002; 40:78 – 89.
16. Kilpatrick ES, Rigby AS, Atkin SL. Variability in the relationship between mean plasma glucose and HbA1c: Implications for the assessment of glycemic control. Clin Chem. 2007; 53:897 – 901.
17. Consensus Committee. Consensus statement on the worldwide standardization of the hemoglobin A1c measurement. Diabetes Care 2007; 30:2399-2400
18. Geistanger A, Arends S, Berding C, Hoshino T, Jeppsson JO, Little R, Siebelder C, and Weykamp C. Statistical methods for monitoring the relationship between the IFCC reference measurement procedure for hemoglobin A1c and the designated comparison methods in the United States, Japan, and Sweden. Clin Chem. 2008; 54:1379 – 1385.
19. Hoelzel W, Weykamp C, Jeppsson JO, Miedema K, Barr J, Goodall, et al. IFCC reference system for measurement of hemoglobin A1c in human blood and the national standardization schemes in the United States, Japan, and Sweden: a method-comparison study. Clin Chem. 2004; 50:166 – 174.
20. Kobold U, Jeppsson JO, Duelffer T, Finke A, Hoelzel W, Miedema K. Candidate reference methods for hemoglobin A1c based on peptide mapping. Clin Chem. 1997; 43:1944 – 1951.
21. Bell JR. The new glycohemoglobin standard. Clinical Laboratory News, 2008; 34:1, 3-4.
22. Jones W, Scott J, Leary S, Stratton F, Smith S, Jones R, Day A, Ness A, ALSPAC Study Team. Stability of whole blood at –70oC for measurement of Hemoglobin A1c in healthy individuals. Clin Chem 2004; 50: 2460–2461.
23. Sacks DB. Translating hemoglobin A1c into average blood glucose: Implications for clinical chemistry. Clin Chem 2008; 54:1756 – 1758.
24. Nordin G and Dybkaer R. Recommendation for term and measurement unit for HbA1c. Clin Chem Lab Med. 2007; 45:1081 – 1082.
25. Mosca A, Goodall I, Hoshino T, Jeppsson JO, Johm WG, Little RR, Miedema K, Myers GL, Reinauer H, Sacks DB, and Weykamp CW. Global standardization of glycated hemoglobin measurement: the position of the IFCC working group. Clin Chem Lab Med. 2007; 45:1077 – 1080.

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