Red cell distribution width [RDW] and standard deviation [SD] of red cell volume in differentiation between iron deficiency and beta thalassaemia trait

ABSTRACT

Blood samples of 59 beta thalassaemia carriers and 50 iron deficient patients were studied with a Coulter counter model S plus III to evaluate the reliability of two red cell parameters in differentiation between microcytosis of beta thalassaemia and iron deficiency. These are red cell distribution width [RDW] and standard deviation of red cell volume [SD]. RDW was directly obtained by the counter and SD was calculated from the manufacturer's formula RDW = SD/MCV x 100 x 1.15. Both parameters proved useful for discrimination between the two disorders. However, SD was superior to RDW in this respect