Hemoglobin A1c plus AEG

Test Code

HBA1G

Alias/See Also

Epic: LAB90

A1c
Glycohemoglobin
HBA1C
Hemoglobin A1c

Includes

Hemoglobin A1C
Average Estimated Glucose

Preferred Specimen

Specimen Type: Whole blood EDTA
Collection Container: Lavender top (EDTA)
Specimen Volume: 3 mL

Minimum Volume

1.0 mL

Instructions

Be sure to fill tube completely.
Send specimen in original tube. Do not aliquot.

Specimen Stability

Room temperature: 8 hours
Refrigerated: 7 days
Frozen: Unacceptable

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Unlabeled, mislabeled, wrong tube type, hemolyzed, visually lipemic, clotted, QNS, exceeds specimen/stability requirements.

Methodology

Enzymatic

Setup Schedule

Daily

Report Available

Same day

Limitations

The Hemoglobin A1c assay is susceptible to interference effects from conjugated bilirubin at > 15.0 mg/dL (180 μmol/L),unconjugated bilirubin at > 10.0 mg/dL (171 μmol/L) and Triglycerides >3000 mg/dL.
Glycated HbF is not detected by the assay as it does not contain the β-chain that characterizes HbA1c. However, HbF is measured in the total Hb assay and as a consequence, specimens containing high amounts of HbF (> 5%) may result in lower than expected mmol/mol HbA1c values (IFCC) and %HbA1c values (NGSP).
If patient has a known homozygous or double heterozygous hemoglobinopathy, HBA1C results may be inaccurate. Fructosamine is the method of choice for those patients.

Reference Range

4.6-5.6 %

Per ADA guidelines Hemoglobin A1c values of 5.7-6.4%
indicate an increased risk for developing diabetes mellitus.
Hemoglobin A1c values greater than or equal to 6.5% are
diagnostic of diabetes mellitus. A Triglyceride result
greater than 3000 mg/dL can falsely decrease HBA1C results.
Congenital hemoglobinopathy can falsely lower the Hemoglobin
A1c values – Boronate-affinity HbA1c is recommended.

Clinical Significance

HbA1c is formed by the reaction of glucose with the N-terminal amino group of the hemoglobin beta chain. The Diabetes Control and Complications Trial (DCCT) Research Group previously reported a relationship between percent HbA1c and mean blood glucose levels during the preceding 2‑3 months. The DCCT study also demonstrated that long-term control of diabetes can prevent complications such as cardiovascular disease, retinopathy, nephropathy, and neuropathy. Measurement of percent HbA1c is the method of choice for monitoring therapy of diabetic patients.

Performing Laboratory

Inova Laboratories

2832 Juniper Street

Fairfax, VA 22031

Last Updated: April 19, 2023
Last Review: N. Wolford, April 19, 2023

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.