transfusions and can pose major problems in the case of long-term transfusion therapy. Several authors found that RBC alloimmunization mainly occurs after the first few transfusions. RBC antibodies, which can become undetectable over time, can cause delayed transfusion reactions after incompatible blood transfusions.53 The matching of donor and recipient RBC phenotypes to avoid sensitization in chronically transfusion dependent patient populations is recommended.
Iron Overload Hemochromatosis occurs in approximately 1 in 200 white persons of Western European descent, and it increases the propensity to absorb excess iron. Iron overload associated with hemochromatosis can cause hepatic cirrhosis, primary liver cancer, arthropathy, diabetes mellitus, other endocrinopathic disorders, and a reduction in lifespan55. Early diagnosis and appropriate management can avoid these complications of iron overload. Therapeutic phlebotomy appears to be the most effective way to reduce the body’s iron stores, and therefore it is the preferred treatment for iron overload associated with hemochromatosis. It is believed that persons with hemochromatosis who were volunteer blood donors prior to diagnosis may have less severe iron overload than those who were not donors, and therefore the former may have a reduced risk of developing complications of iron overload.55 However Barton et al55, in a study to determine if volunteer blood donation before diagnosis decreases the severity of iron overload at diagnosis in persons with hemochromatosis concluded from their study that routine blood donation does not, on average, decrease the severity of iron overload in persons with hemochromatosis.55
Hypertransfusion with baseline hemoglobin of 10 to 12 g/dL is considered to be the mainstay of conservative therapy for beta-thalassemia major. However, this regimen is frequently associated with manifestations of transfusion iron overload, despite regular chelation therapy with subcutaneous desferoxamine.54 In a study to verify whether a transfusion regimen with a target pretransfusion hemoglobin level between 9 and 10 g/dL can result in a significant reduction in blood transfusion, while still effectively suppressing erythropoiesis, Cazzola et al54, reviewed the records of 32 beta- thalassemia major patients, who were maintained at a pretransfusion hemoglobin of 11.3 +/- 0.5 g/dL between 1981 and 1986. At the beginning of 1987 the patients were switched to a transfusion regimen with pretransfusion hemoglobin of 9.4 +/- 0.4 g/dL. The degree of erythroid marrow activity was evaluated in the patients and in 32 subjects with beta-thalassemia intermedia through the measurement of serum transferrin receptor.54 Upon adoption of the moderate transfusion regimen, they noted that transfusion requirements decreased from 137 +/- 26 to 104 +/- 23 mL/kg/year of RBC, and mean serum ferritin decreased from 2448 +/- 1515 to 1187 +/- 816 g/L. A half of the patients achieving serum ferritin levels lower than 1000 g/L. They observed that the proportion of patients having spontaneous pubertal development increased significantly, as a result of less iron-related gonadotropin insufficiency. At the lower pretransfusion hemoglobin, erythroid marrow activity did not exceed two to three times normal levels in most subjects. They concluded that as compared with hypertransfusion, moderate transfusion might permit more effective prevention of iron loading, with higher likelihood of spontaneous pubertal development and without producing excessive expansion of erythropoiesis.54 Immunosuppression Blood transfusions may suppress the recipient’s immune system and produce a transfusion risk is called immunomodulation. This risk appears to be strongly associated to the presence of donor leukocytes in the transfused product. Immunosuppression may lead to life-threatening events, such as multiple organ failure, increased risk of infection after surgery and/or diminished prospect of cure in patients with certain malignancies.18,56 Other effects of immunosuppression include decreased rates of allograft rejection, decreased incidence of repetitive spontaneous abortion, and a decreased rate of recurrence of Crohn's disease.18 Transfusion-associated immune suppression has been seen to results in increased incidence of infection in transfused patients after trauma and surgery.56 Clinical studies have shown that leukocyte reduction by filtration of blood components may reduce transfusion associated immunosuppression and decrease the rate of postoperative infections.56 Preoperative autologous blood donation is commonly used to reduce exposure to allogeneic transfusion among patients undergoing elective surgery, with the aim of limiting the occurrence of