Developing a reference system for the IFCC standardization of HbA2

- EQAS on HbA2 shows that improvement in the state-of-the-art of routine methods is necessary.
- 7% allowable total error is a recommended goal.
- A reference measurement procedure based on isotopic dilution and mass spectrometry is proposed.
- A lyophilized candidate reference material is proposed.

The importance of hemoglobin A2 (HbA2) as an indicator of the presence of β-thalassemia was established many years ago. However, clinical application of recommended HbA2 cut off values is often hampered due to poor equivalence of HbA2 results among methods and laboratories. Thus, the IFCC standardization program for HbA2 was initiated in 2004 with the goal of achieving a complete reference system for this measurand. HbA2 standardization efforts are still in progress, including the development of a higher-order HbA2 reference measurement procedure and the preparation of a certified reference material in collaboration with the IRMM. Here, we review the past, present and future of HbA2 standardization and describe the current status of HbA2 testing.