Transfusion and exchange transfusion in sickle cell anaemias, with particular reference to iron metabolism.

The relationship between the number of units of blood transfused and indicators of iron status in 37 patients with sickle cell anaemia (Hb SS), SC disease (Hb SC) or S beta-thalassaemia has been studied. The correlation coefficient between serum ferritin and the number of units transfused was good (r = 0.86), provided that ferritin samples taken within one week following a crisis were excluded. The relationship of transfusion history to serum ferritin in the steady state showed a similar relationship to that previously observed for other multiply transfused patients. The serum ferritin taken within 7 days of a painful crisis was significantly greater than the serum ferritin from the same patients in the steady state (p less than 0.025). The serum alanine transaminase did not rise as consistently as the serum ferritin during crises; it correlated with the serum ferritin but not the transfusion burden in the steady state. Transferrin iron saturation correlated less clearly with transfusion history than serum ferritin (r = 0.62). Patients who had received exchange transfusions were less likely to be iron-overloaded (ferritin increment per unit of blood = 9.9 +/- 3.8 micrograms/l) than patients who had received an equivalent number of units by conventional transfusion (ferritin increment per unit of blood transfused = 25.1 +/- 2.42 micrograms/l).