Reference intervals for HbA2 and HbF and cut-off value of HbA2 for β-thalassemia carrier screening in a Guizhou population of reproductive age

Abstract

ObjectiveThe aims of this study were to establish the reference intervals for HbA2 and HbF in a Guizhou population of reproductive age, and to determine the cut-off value of HbA2 for β-thalassemia carrier screening. MethodsHemoglobin analysis was performed on 832 individuals without hypochromic microcytic anemia to calculate the reference intervals for HbA2 and HbF. Three hundred and ninety one β-thalassemia carriers and non β-thalassemia individuals were analyzed for their HbA2 levels followed by detecting β-globin gene mutations, then cut-off value of HbA2 for β-thalassemia carrier screening was determined using ROC curve analysis. ResultsThe reference interval for HbA2 in overall normal individuals was 2.3%–3.1%, and reference intervals for HbF in normal males and females (including normal females and pregnant women) were 0–0.5% and 0–1.0% respectively. The cut-off values of HbA2 for β-thalassemia carrier screening in males, non-pregnant women, pregnant women and the overall set were 4.40%, 3.75%, 3.70% and 3.95% respectively. ConclusionGender and pregnancy status had no obvious influence on reference interval for HbA2. The HbF level was higher in females than in males, but pregnancy status had no obvious influence on HbF level. Cut-off value of HbA2 for β-thalassemia carrier screening was obviously affected by gender but not by pregnancy status.