Can automated haematology analysers discriminate thalassaemia from iron deficiency?

The use of automated analysers in population screening for beta-thalassaemia has been a matter of controversy. The new fully automated haematology analyser Sysmex E-5000 (Toa Medical Electronics Co. Ltd) facilitates the discrimination of heterozygous thalassaemia from iron deficiency anaemia. In addition to haemoglobin, mean corpuscular haemoglobin and mean corpuscular volume, the red cell size-distribution width is measured. In patients with hypochromic microcytic red cells, the Sysmex data have been evaluated and compared with the indices described by England and Fraser [Lancet i, pp. 449-452, 1973], Mentzer [Lancet i, p. 882, 1973] and by Shine and Lal [Lancet i, pp. 692-694, 1977]. For the detection of beta-thalassaemia trait, the size-distribution width is superior to the previously described indices. The sensitivity is 79%, the specificity 95% and the predictive value for a positive test 94%.