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Test Code LAB601 Hemoglobin A1c, Blood

Additional Codes

Test Name in EPIC EPIC Test Code Mnemonic
HEMOGLOBIN A1C LAB601 HGA1C

 

Useful For/Utility

  • Evaluating the long-term control of blood glucose concentrations in patients with diabetes
  • Diagnosing diabetes
  • Identifying patients at increased risk for diabetes (prediabetes)

This assay is not useful in determining day-to-day glucose control and should not be used to replace daily home testing of blood glucose.

Methodology

High-performance liquid chromatography (HPLC) on the BioRad D10 and Point-of-Care Immunoassay for the DCA Vantage.  Enzymatic on the Abbott Alinity.

Clinical Information

HbA1c is the fraction of hemoglobin A that is first reversibly, then irreversibly glycated at one or both N-terminal valines of the β-chain.1 The longer red blood cells are in circulation and the higher the ambient glucose levels, the higher the concentration of HbA1c. HbA1c reflects the average blood glucose level during the preceding 2 to 3 months. The HbA1c assay is useful as an aid in the:• diagnosis of diabetes mellitus,• identification of patients at risk for developing diabetes, and• monitoring of patients with diabetes mellitus. For monitoring diabetic patients, it is recommended that glycemic goals are individualized following current professional society recommendations. As recommended by the American Diabetes Association (ADA), patients in the range of 5.7 to 6.4 %HbA1c (39 to 46 mmol/mol) would be in the category of increased risk for diabetes and results ≥ 6.5% (48 mmol/mol) may aid in the diagnosis of diabetes. Several studies, including the Diabetes Control and Complications Trial (DCCT), have shown that long-term control of diabetes can prevent complications such as cardiovascular disease, retinopathy, nephropathy, and neuropathy. Measurement of HbA1c can be invaluable in the monitoring of glycemic control of diabetic patients.

Specimen Requirements

Specimen Type: Whole blood

Container/Tube: Lavender top (EDTA)

Specimen Volume: 2 mL

Specimen Minimum Volume: 0.5 mL

Whole blood EDTA must be collected by standard venipuncture techniques (capillary not acceptable unless sending to Duluth's SMMC lab to be performed on the DCA Vantage analyzer).

Collection Instructions: Do not centrifuge.

Specimen Transport Temperature

Refrigerate 5 days/Frozen NO/Ambient 8 hrs.

Day(s) Test Set Up

Monday through Sunday

Performing Laboratory

Minnesota North Dakota Wisconsin
Duluth Family Medicine Clinic Fargo Hospital Ashland Clinic
SMDC Clinical Lab (Duluth) South University Clinic (Fargo)  
St. Joseph's Medical Center (Brainerd)     

Test Classification and CPT Coding

83036

Reference Values

≥ 6.5% Diabetes*

5.7-6.4% Impaired glucose tolerance

4.0-5.6% Normal

 

* In the absence of unequivocal hyperglycemia, results should be confirmed by repeat testing for the diagnosis of diabetes. American Diabetes Association 2018

 

Note:  Both the HgA1c and Estimated Average Glucose (eAG) results will be reported.

Correlation with hemoglobin A1c (HgA1c) and glucose control is as follows:

HgA1c Result

(%)

Estimated Average Blood Glucose

(mg/dL)

6.0 126
6.5

140

7.0 154
7.5 169
8.0 183
8.5 197
9.0 212
9.5 226
10.0 240
Every sustained decrease of HgA1c of 1% results in a 25% decrease in the risk of developing diabetic microvascular complications.