Blood indices to differentiate between β-thalassemia trait and iron deficiency anemia in adult healthy Egyptian blood donors

Background β-Thalassemia trait (BTT) often shows microcytosis, a normal or an increased red blood cell (RBC) count, and an elevated level of HbA 2 , which provide the basis for laboratory screening. BTT is an important differential diagnosis of iron deficiency anemia (IDA). Donors with BTT have hemoglobin values comparable with normal; hence, they are accepted for donation and they usually escape diagnosis. Aim The aim of this work was to differentiate BTT from IDA through blood indices performed in routine complete blood count. Patients and methods A total of 200 samples were obtained from apparently healthy adult Egyptian blood donors randomly. Complete blood count and mean corpuscular volume (MCV) were performed to all individuals. Hemoglobin electrophoresis and/or serum ferritin was performed to samples with MCV less than 78 fl. Results Prevalence of BTT in this study was 6%, whereas IDA represented 4.5% of total 200 samples investigated. The cutoff value of MCV 73 fl was 91.7% sensitive and 100% specific in differentiating BTT from IDA. Red blood cell distribution width at level 14.5% or below can differentiate BTT from IDA with 83.3% sensitivity and 100% specificity. RBCs count at value above 5.47 million/mm 3 can differentiate BTT from IDA with 100% sensitivity and 100% specificity. Conclusion The cutoff values of MCV 73 fl or less, RBC count above 5 × 10^6 /mm^3 , and red blood cell distribution width 14.5% or less were suggested to be associated with a high probability of BTT.