Anemia and the blood donor

The World Health Organization recommends a collection rate of 10-20 whole blood units per 1000 inhabitants to address transfusion needs(1). However, demand for blood is ever-increasing as medicine continuous to develop(2). Donor selection is critical to blood transfusion safety and blood donor eligibility policies are designed to protect both the donor and the recipient(1,3). Donors with relatively low hemoglobin (Hb) levels are not allowed to donate to prevent them from developing iron deficiency anemia (IDA). In addition, deferral of these donors guarantees that blood units for transfusion meet the required standards for Hb content(4). Deferral for low Hb accounts for 35% to 75% of total deferrals, with the vast majority occurring in women(5-7). At the New York Blood Center, 92.7% of these deferrals were women(6,7). Iron deficiency is the world’s most widespread nutritional disorder, affecting both industrialized and developing countries(8). In Brazil, there are no consistent studies to show the real problem, although some studies showed 25% of anemia in women of childbearing age(9,10). On the other hand, because IDA is the last stage of iron-deficiency, Hb measurement alone is inadequate to detect blood donors with iron deficiency but without anemia. Recent publications have suggested that serum ferritin levels could be a reliable indicator for body iron stores since they provide a determination of iron deficiency at an early stage(11,12). As ferritin testing is comparatively costly, various red blood cell (RBC) parameters have been proposed as markers for low ferritin/iron depletion(13). Significant correlations between ferritin and RBC parameters were shown in these analyses, but no study has determined which marker is the most useful to identify donors at risk of developing anemia(13). Beta-thalassemia trait (BTT) is the second most common cause of microcytic anemia and, for this reason, the possibility of this disease must be discarded when anemia or microcytosis is present(12,14). An interesting paper by Tiwari et al.(14) suggested that it could be useful to routinely perform a complete blood count (CBC) for all blood donors and further analyze the microcytic samples for ferritin and Hemoglobin A2 to differentiate between IDA and BTT. This approach, however, is relevant only in areas where there is an elevated prevalence of BTT. These authors, also, reviewed nine indices to differentiate IDA and BTT. (Table 1) Maria Stella Figueiredo