Measurement of HbA_1c and HbA₂ by Capillarys 2 Flex Piercing HbA_1c programme for simultaneous management of diabetes and screening for thalassemia

Introduction: Thalassemia could interfere with some assays for haemoglobin A_1c (HbA_1c) measurement, therefore, it is useful to be able to screen for thalassemia while measuring HbA_1c. We used Capillarys 2 Flex Piercing (Capillarys 2FP) HbA_1c programme to simultaneously measure HbA_1c and screen for thalassemia.

Materials and methods: Samples from 498 normal controls and 175 thalassemia patients were analysed by Capillarys 2FP HbA_1c programme (Sebia, France). For method comparison, HbA_1c was quantified by Premier Hb9210 (Trinity Biotech, Ireland) in 98 thalassaemia patients samples. For verification, HbA_1c from eight thalassaemia patients was confirmed by IFCC reference method.

Results: Among 98 thalassaemia samples, Capillarys 2FP did not provide an HbA_1c result in three samples with HbH due to the overlapping of HbBart's with HbA_1c fraction; for the remaining 95 thalassaemia samples, Bland-Altman plot showed 0.00 ± 0.35% absolute bias between two systems, and a significant positive bias above 7% was observed only in two HbH samples. The HbA_1c values obtained by Capillarys 2FP were consistent with the IFCC targets (relative bias below ± 6%) in all of the eight samples tested by both methods. For screening samples with alpha (α-) thalassaemia silent/trait or beta (β-) thalassemia trait, the optimal HbA₂ cut-off values were ≤ 2.2% and > 2.8%, respectively.

Conclusions: Our results demonstrated the Capillarys 2FP HbA_1c system could report an accurate HbA_1c value in thalassemia silent/trait, and HbA₂ value (≤ 2.2% for α-thalassaemia silent/trait and > 2.8% for β-thalassemia trait) and abnormal bands (HbH and/or HbBart's for HbH disease, HbF for β-thalassemia) may provide valuable information for screening.