Standardization of hemoglobin A2 and hemoglobin F: Achievements and perspectives.

The establishment of reference systems for the standardization of hemoglobin A2 (HbA2) and fetal hemoglobin (HbF), both critical for improving diagnostic accuracy in conditions such as β-thalassemia and sickle cell disease, are described. Efforts were led by the IFCC and other groups to address and reduce the variability in laboratory measurements of these hemoglobins. This document outlines the production of certified reference materials (CRMs) for HbA2 and the development of a reference measurement procedure using isotope dilution mass spectrometry. Similarly, standardizing HbF is essential for supporting diagnostic and therapeutic strategies, particularly in managing sickle cell disease. HbF levels can predict disease outcomes and guide treatment plans. Significant challenges remain in achieving consistent measurement across laboratories, and the process for standardization for this minor hemoglobin has just begun. We are confident that the implementation of these reference systems will provide improved accuracy and traceability in the future.