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|Test Update Information||Effective July 9, 2012, HbA1c testing will be performed using the Bio-Rad Variant II Turbo 2.0 and the Bio-Rad D-10 HPLC systems. No significant change in results should be noticed. No change in reference values.|
|Test group||Hemoglobin A1c|
|Performed by||China Basin Chemistry|
|In House Availability||Monday-Friday (day shift)|
|Method||Bio-Rad Variant II Turbo 2.0 (HPLC-Ion Exchange)|
|Container type||Lavender top|
|Amount to Collect||1 mL blood|
|Sample type||EDTA whole blood|
|Preferred volume||1 mL blood|
|Processing notes||Do not centrifuge.|
|Normal range||Non-Diabetic: 4.3-5.6%|
|Synonyms||Glyco-hgb; Glycohemoglobin; Glycosylated hemoglobin; Hgb A1; HgbA1c; Glycated hemoglobin|
|Turn around times||1-3 days|
|Additional information|| Interferences:
A Hgb F level of >25% as well as some mutant hemoglobins will interfere with the assay. Hemoglobin variants S, C, D & E have no effect on the assay when they exist in the heterozygous state.
Serum glycated albumin (fructosamine) testing can be ordered as an alternative means of monitoring glucose control when interferences preclude following A1c by this method.
In diabetic patients who have experienced recent blood loss, hemolysis, or have elevated reticulocyte counts for other reasons, the HgBA1c level may be lowered and may not reflect actual glycemic control.
Management of Diabetes:
Goals for HbA1c management recommended by American Diabetes Association (ADA) Standards of Medical Care in Diabetes (Diabetes Care, Volume 33, Supplement 1, January 2010) are as follows:
When using this assay, the ADA recommended goal for A1c control for adult diabetic patients in general is <7% although use of an A1c goal as close to normal as possible without causing significant hypoglycemia may be appropriate for individual patients. In pregnant patients with diabetes, the ADA recommends aiming for the range < 6% if it can be achieved without excessive hypoglycemia.
The ADA recommended goals for other age groups are:
Diagnosis of diabetes or increased risk for diabetes: The American Diabetes Association recommends the following HbA1c cutoffs when assessing increased risk for diabetes and when diagnosing diabetes.
Note: In the absence of unequivocal hyperglycemia, the diagnosis of diabetes should be confirmed by repeat testing.
Receiver operating curve analyses of nationally representative U.S. data (NHANES 2005–2006) indicate that among the nondiabetic adult population, an A1C value of 5.7%, compared with other cut points, has the best combination of sensitivity (39%) and specificity (91%) to identify cases of impaired fasting glucose (FPG ≥ 100 mg/dl [5.6 mmol/l]). Note that individuals with an A1c < 5.7% may still be at risk, depending on the level of A1c and presence of other risk factors, such as obesity and family history. Individuals with an A1c > 6% should be considered at very high risk for diabetes.
The Variant II Turbo Hemoglobin A1c 2.0 Program and the D-10 Dual Program have been certified by the NGSP (National Glycohemoglobin Standardization Program) as having documented traceability to the Diabetes Control and Complications Trial reference method. These HPLC ion exchange methods yield results that correspond closely to results obtained in independent reference laboratory assays. In patients with elevated A1c levels, results determined by the point of care DCAVantage device may run approximately 0.4 units lower than this HPLC method.
The coefficient of variation (CV) for these HPLC assays around A1C levels of 6 – 9 is < 2%. Based on the CV of these assays, there is a 95% probability that a change in A1c results of 0.5 units or more is real and not due to analytic variation (Little RR, et al, Clinical Chemistry 57:205-214, 2011).
|Last Updated||2/17/2015 3:20:57 PM|
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