Sanchaisuriya K et al. - E level < 26%, MCV < 74 fl, and MCH < 24 pg could be used for screening alpha^o-thalassemia in heterozygous Hb E. However, to improve specificity and PPV of the tests, a combination of Hb E level < 26% with either MCV < 74 fl or MCH < 24 pg is recommended.