Standard Operating Procedure: HbA1c Testing
1. Purpose: Monitor 2-3 month average blood glucose levels in diabetic patients.
2. Specimen: Whole blood (EDTA preferred).
3. Reagents: HPLC buffers or immunoturbidimetric reagents (NGSP-certified methods).
4. Procedure (HPLC Method):
- Hemolyze whole blood sample.
- Inject into cation-exchange HPLC column.
- HbA1c elutes at a specific retention time due to its altered charge.
- Quantify via spectrophotometric detection, reporting as % of total hemoglobin.
5. Reference Ranges
- The canonical adult reference interval for HbA1c is shown in the Reference Ranges panel below.
Decision Limits (ADA diagnostic categories)
- Normal: < 5.7%
- Prediabetes: 5.7-6.4%
- Diabetes: ≥ 6.5%