Pattern of red cell indices in beta thalassemia trait and E trait

Background: Thalassemia is the most common single gene disorder that affects globin chain synthesis. Hb electrophoresis is the gold standard for detection of beta thalassemia trait and E-trait, but it is costly and not available in upazila and district level of Bangladesh. Red blood cell (RBC) indices such as RBC count, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and red cell distribution width (RDW) may be useful for physicians to predict beta thalassemia trait and E-trait. These indices are derived by automated cell counters, which is widely available. The goal of this study is to detect the pattern of red cell indices in beta thalassemia trait and E-trait which may guide physicians for further planning of confirmatory test. Method: This was a Cross-sectional observational study. Patients diagnosed as beta thalassemia trait and E-trait by hemoglobin electrophoresis who does not have concomitant iron deficiency anemia or anemia of chronic diseases were included in the study. Results: There were 98 participants with mean age of 26.98 (±14.72) years. Among the participants 51(52%) were E-trait and 47(48%) were beta thalassemia trait. Mean hemoglobin of E-trait and Beta thalassemia trait are 11.79(±1.53) and 10.68(±1.05) respectively (p<0.001). Mean RBC count of E-trait and Beta thalassemia trait are 4.94(±0.62)x106/µL and 5.28 (±0.61)x106/µL respectively (p=0.008). Mean MCV of E-trait and Beta thalassemia trait are 73.33(±5.81) fl and 62.68(±5.05) fl respectively (p<0.001). Mean MCH of E-trait and Beta thalassemia trait are 23.83(±2.08) pg and 20.17(±1.7) pg respectively (p<0.001). Mean MCHC of E-trait and Beta thalassemia trait are 32.50(±1.42) g/dL and 32.20(±1.56) g/dL respectively (p=0.320). Mean RDW-CV of E-trait and Beta thalassemia trait are 15.11(±1.07) % and 16.24(±1.46) % respectively (p<0.001). To determine cut off value of different parameter for diagnosis of E-Trait compared to Beta trait, the ROC curve was drawn. A MCV Cutoff value of 67.40 (fl) gives 88.2% sensitivity and 83.0% specificity for the diagnosis of E‑trait. A MCH Cutoff value of 21.4 pg gives 90.2% sensitivity and 83.0% specificity for the diagnosis of E trait. A hemoglobin cutoff value of 10.85 g/dl can be used with 66.7% sensitivity and 59.4% specificity for diagnosis of E trait. RDW-CV cutoff value of 15.35% can be used with 72.3% sensitivity and 66.7% specificity for diagnosis of beta thalassemia trait. Conclusion: Hemoglobin, MCV, MCH, and RDW-CV can be a very good parameter to differentiate between E-trait and Beta thalassemia trait. Further study with large sample including normal people can help us to set a differentiating point between trait and normal people.