Preanalytical Considerations for HbA1c Testing

Anticoagulant Selection

EDTA is the recommended anticoagulant for HbA1c measurement and may be used for all assays unless the manufacturer specifies an alternative anticoagulant. 1

Storing whole‑blood specimens at elevated temperatures (e.g., room temperature > 30 °C) can introduce significant errors in HbA1c results, compromising analytical accuracy. 2
When kept refrigerated at 4 °C, whole‑blood samples remain stable for up to one week, preserving reliable HbA1c values during this period. 1
For long‑term preservation, specimens should be frozen at ‑70 °C or colder; storage at ‑20 °C is insufficient and may degrade HbA1c integrity. 2

EDTA itself is not classified among the substances that interfere with HbA1c assays; known interferents include marked hypertriglyceridemia, severe hyperbilirubinemia, and certain high‑dose vitamins used in older assay platforms. 3