Approach to blood donors with microcytosis.

The aim of this paper is to find microcytosis in donors, to establish prevalence of iron deficiency anaemia (IDA) and beta-thalassemia trait (BTT) in them and to evaluate which index is most effective in differentiating these two conditions. IDA and BTT are the most common causes of microcytic anaemia. Traditional approach is trial of iron treatment. Where thalassemias are common, this can lead to iron overload and failure to provide diagnosis/counselling in BTT. Initially 925 donor samples were evaluated on cell counter. Of these, 50 were found microcytic. These were subjected to Ferritin and HbA2 determination. Subsequently, additional 51, age- and sex-matched normocytic donor samples were selected as controls. These were subjected to the same tests. Nine indices namely RBC, RDW, Mentzer's, Shine and Lal, England and Fraser, Srivastava, Green and King, RDW index and Ricerca were used to differentiate IDA and BTT. Prevalence of microcytosis was 5.4%. Of these microcytic samples, 52% were IDA, 36% were BTT, 8% had both and 4% were undiagnosed. IDA had significantly lower Hb, mean corpuscular volume (MCV) and Ferritin levels than the control group. BTT had lower MCV, higher Ferritin and comparable Hb levels with control group. The Youden's index of Mentzer's was highest and RBC was the only index which had both sensitivity and specificity more than 80% for both IDA and BTT. It is desirable to routinely perform hemograms for all blood donors and further analyse the microcytic samples for Ferritin and HbA2 to diagnose IDA and BTT and to provide appropriate counselling/treatment.