The Study of Mean Corpuscular Volume for Differentiation of Hemoglobin E Carrier from Normal
In the routine severe thalassemia risk couple screening, pregnant woman or her couple who has normal mean corpuscular volume (MCV) will be tested for hemoglobin E. If the MCV that differentiates hemoglobin E carrier and normal can be defined, a substantial amount of budget, workload and turnaround time will be reduced. The objectives of this study were to evaluate the prevalence of hemoglobin E among normal MCV and define the MCV that can differentiate hemoglobin E carrier from normal. The 1,015 EDTA blood samples were collected from pregnant women or her couples who attended the ANC clinic of Somdejphrachaotaksinmaharaj hospital, Tak province, Thailand. The blood cell count automation was used for MCV analysis, and simple E screen test kits were then used for hemoglobin E screening whenever the MCV was normal. The data was collected by subject descriptions, hematologic data and hemoglobin E screening test, followed by calculating the percentage of hemoglobin E in each range of MCV. Finally the MCV which can differentiate hemoglobin E trait and normal was defined by ROC curve. The results showed that of all 1,015 subjects with 83 % female, age 26.6 + 6.3 years, the mean + SD of red cell count, hemoglobin, hematocrit, MCV and MCH were 4.5 + 0.5 M/uL, 12.9 + 1.3 g/dL, 38.9 + 3.9 %, 87.3 + 4.6 fL, and 29.0 + 1.9 pg, respectively. By screening test kits, 70 of 1,015 (6.9 %) were hemoglobin E positive and at MCV > 90.0 fL no hemoglobin E was found. The data revealed that there were 6.9 % hemoglobin E among normal MCV samples and that 90 fL is the optimal MCV that can be used to differentiate hemoglobin E carrier from normal with 100 % specificity.
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