Hemoglobin (Hgb) A<sub>1c</sub>
| Hemoglobin (Hgb) A1c | | | |
| Number | | 001453 |
| CPT | | 83036 |
| Related Information | | Glycohemoglobin (GHB), Total |
| Synonyms | | Hb A1c |
| Specimen | | Whole blood |
| Volume | | 7 mL |
| Minimum Volume | | Pediatric EDTA whole blood tubes may be used. Please place the entire tube in a transport tube for shipment to the laboratory. |
Container | | Lavender-top (EDTA) tube, green-top (heparin) tube. Other
anticoagulants have not been tested or found acceptable. |
| Collection | | The usual precautions in the collection of venipuncture samples should be observed. The sample must be free of clots. Samples with any hematocrit disorders can lead to erroneous results. Send entire tube to the laboratory. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested. |
| Storage Instructions | | Maintain specimen at room temperature. Stable for up to 7 days. Stable when refrigerated for up to 28 days and when frozen for up to 6 months. |
| Causes for Rejection | | Clotted specimen |
| Reference Interval | | Diabetic Adult <7.0%
Healthy Adult 4.8% to 5.9%
(DCCT/NGSP)
American Diabetes Association's Summary of Glycemic
Recommendations for Adults with Diabetes: Hemoglobin A1c
<7.0%. More stringent glycemic goals (A1c <6.0%) may
further reduce complications at the cost of increased risk
of hypoglycemia. |
| Use | | Clinically, hemoglobin A1c values are used most frequently to assess glucose control in insulin-dependent diabetics whose glucose levels are very labile and in whom single blood glucose measurements may not accurately reflect the level of control present over the preceding few weeks. Hemoglobin A1c measurements are of less value in stable diabetics, because urine and blood glucose determinations provide simple, economic, and reliable means for assessing glycemic control. In these patients, fasting glucose concentrations are fairly consistent from day to day and there is a significant correlation between hemoglobin A1c and single fasting glucose levels. Although measurement of hemoglobin A1c may provide a unique means of evaluating control in diabetics who have wide fluctuations in blood glucose levels, it is not a substitute for urine and blood glucose levels that are used to regulate insulin dose. Hemoglobin A1c measurements are less sensitive in detecting what is now defined as diabetes than is the GTT. |
| Limitations | | This method is free of interference from elevated levels of fetal hemoglobin (Hb F) found in young children younger than 2 years of age and in some hemoglobinopathies. It also is free from interference from hemoglobins H, I, J, N, S, G, D, C, and E. |
| Methodology | | Roche Tina Quant |
| Additional Information | | Factors such as duration of diabetes, adherence to therapy,
and age of patient should also be considered in assessing
the degree of blood glucose control. |
| References | | Bergstrom RW, Kelley JR, and Ward WK. Fetal
Hemoglobin Alters Hemoglobin A1c Measurements.
Ann Intern Med. 1991; 115(8):656.
Krauss JS and Khankhanian NK. HPLC
Determination of Hemoglobin A1c in the Presence
of the Fast Hemoglobin I Philadelphia. Clin Chem.
1989; 35(3):494-495.
Holt GS, Wofford JL, and Velez
R. Hemoglobinopathies Affect Hemoglobin A1c
Measurement. Ann Intern Med. 1991; 115:68-69.
Fairbanks VF and Zimmerman BR. Measurement of
Glycosylated Hemoglobin by Affinity Chromatography.
Mayo Clin Proc. 1983; 58(11):770-773.
American Diabetes Association: Clinical
Practice Recommendations 2008. Diabetes Care. 2008;
31:Supplement 1. |
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