Haemoglobin A1c (HbA1c)
Normal Reference Range
HbA1c (DCCT-aligned)
<6.4%
HbA1c (IFCC Reference)
<46 mmol/mol
Test Information
Glycosylated haemoglobin, often known as HbA1c, is a kind of haemoglobin that is typically evaluated to determine the average plasma glucose concentration over time. It is created through a non-enzymatic glycation route that involves plasma glucose exposure of haemoglobin. Over the course of the red blood cell’s lifespan, which is typically 120 days, hemoglobin is glycosylated at a variable (non-linear) rate. This indicates that the average glucose level over the previous 120 days determines the proportional proportion of glycosylated haemoglobin at any one period.
Clinical Indications
Monitoring of Diabetes. However, it has limited utility in the diagnosis of diabetes mellitus.
Note: Where the average RBC lifespan is much less than 120 days, the HbA1c assay is not recommended since up to 50% of glycosylation normally takes place between days 90 and 120. Situations that frequently rule out HbA1c assays include: –
1. Red cell disorders with increased red cell turnover, including anaemia, myelodysplastic disease, haemolysis, and hemoglobinopathies
2. Interferences include carbamylated haemoglobin (in patients with uraemia), persisting foetal haemoglobin, and haemoglobin variations.
Very poorly controlled diabetics: HbA1c readings will be correspondingly misleading in patients who habitually vary between very high and very low plasma glucose levels.
Sample Required
4mL EDTA Whole blood tube is required for the HB A1C blood test
Min. sample volume
0.5mL
Special Instructions and Precautions
None
Time Limits For Retrospective Testing
5 days
Any factors affecting the test
None
Turnaround Time
3 days
Referral centre (if applicable)
Not applicable
Test Code
A1C