RESUMEN
Background: Because of the overlapping MCV, MCH and HbA 2 values in BTT and non-BTT subjects our laboratory determined own cutoffs. Aims: To establish cutoff values by investigating the parents of thalassemia major children and to assess the degree of anemia in BTT subjects. Materials and Methods: Study includes 179 parents of thalassemia major children (BTT cases) and 287 non-BTT controls. Samples were analyzed on an electronic hematology analyzer. The samples having MCV ≤ 76 fl and MCH ≤ 27 pg were quantified for HbA 2 by cellulose acetate electrophoresis and grey zone samples were confirmed on HPLC. Statistical Analysis Mean ± SD, sensitivity, specificity, PPV, NPV and accuracy were calculated. The histograms were plotted for MCV, MCH and HbA 2 . Results: Cases having MCV ≤ 76 fl and MCH ≤ 27 pg if considered as suspected cases of BTT then we could have missed five known BTT samples. Sensitivity increased to 100% in all three diagnostic parameters when the cutoff values were raised and specificity for MCV and MCH was decreased. But specificity was 100% with raised cutoff for HbA 2 . Hb and HCT mean values were significantly reduced in BTT cases compared to controls (P < 0.001). In 100% females and 84.9% males having BTT, mild to moderate anemia was observed. Conclusion: In our setup, the cutoff values are MCV (≤78.0 fl), MCH (≤28 pg) and HbA 2 (>3.8%) for BTT diagnosis and there is a mild to moderate anemia in BTT cases.