Effective screening for a-thalassemia 1, b-thalassemia and Hb E at the Diagnostic Clinical Microscopy Unit, Srinagarind Hospital

Abstract

According to the policy of  the Ministry of  Public Health, severe thalassemia diseases targeted for prevention and control include homozygous a - thalassemia 1 (Hb Bart’s hydrops fetalis), homozygous b - thalassemia and b - thalassemia / Hb E disease. The objective of this study is to evaluate the effectiveness of thalassemia screening using a combined MCV (cut off; 80 fl) and KKU-DCIP-Clear at the Diagnostic Clinical Microscopy Unit, Srinagarind Hospital, Faculty of Medicine, Khon Kaen University. Studied was carried out on 100 subjects. After screening, definite diagnosis of each case was done by standard Hb and DNA analyses. Thalassemia identified included 1 b - thalassemia trait, 1 a - thalassemia 1 trait, 1 Hb E trait with a - thalassemia 1 trait, 5 Hb E trait with a - thalassemia 2, 2 Hb E trait with Hb Con Sp trait, 1 Hb E trait with a - thalassemia 2 / Hb Con Sp, 24 Hb E trait, 3 Homozygous Hb E, 1 homozygous Hb E with Hb Pakse’ trait, 12 a - thalassemia 2 trait, 1 a - thalassemia 2 / Hb Con Sp , 1 Hb Lepore trait and 47 non-thalassemia. No false negative was found for screening of the three important thalassemia carriers but 6 false positive cases were encountered. Therefore, the sensitivity and specificity  of screening for a - thalassemia 1, b - thalassemia and Hb E using MCV and KKU-DCIP-Clear were 100 % and 90.2 %, respectively. The specificity was increased to 91.8 % when another red blood cell parameter, mean cell hemoglobin (MCH) (cut off; 27 pg) was used additionally. This study confirmed that the MCV and MCH values obtained from quality controlled electronic blood cell counter could be used for screening of a and b - thalassemias instead of the OF test. Using MCV and MCH in combination with DCIP test should provide effective screening for severe thalassemia carriers in routine practice.