evaluation of the formulae based on red blood cell indices in differentiating between iron deficiency anemia and beta thalasemia minor

background and aims: iron deficiency anemia (ida) and beta thalassemia minor (btm) are the most common hypochromic microcytic anemias, and it is regarded important to differentiate between them. several formulae can be taken into consideration based on red blood cell (rbc) parameters in order to distinguish between these two disorders. hence, the present study intended to evaluate the sensitivity as well as specificity of some of these formulae. materials and methods: in this cross-sectional study, ida was diagnosed in 200 patients based on hypochromic and microcytic rbc appearance, reduced mean cell volume, mean cell hemoglobin and ferritin as well as increased total iron binding capacity. furthermore, btm was diagnosed via hypochromic microcytic appearance of rbc and increased hemoglobin a2 level. then, ida and btm diagnosis were confirmed using the formulae of king-green, mentzer index, england and fraser, shine and lal, srivastava and sirdah. the sensitivity and specificity of these formulae  were calculated as well. results: the study findings demonstrated that based on the study criteria, out of 200 patients with hypochromic microcytic rbc appearance, 120 were afflicted with ida and 80 suffered from btm. the formulae-based diagnosis demonstrated that king-green formula was the most reliable one. conclusions: although king-green formula had the highest sensitivity and specificity and was the most reliable formula, none of the formulae  revealed 100% sensitivity and specificity. as a result, making definitive distinction between ida and btm is not possible using these formulae.