Iron deficiency and sickle cell anemia.

In a patient with sickle cell anemia, iron deficiency was accompanied by hypochromic, microcytic RBCs, absence of bone marrow iron, and a low serum ferritin level. The mean corpuscular hemoglobin concentration (MCHC) was decreased (27.6 g/dL) and was associated with an extreme scarcity of sickled erythrocytes in blood smears. Iron therapy resulted in reticulocytosis and an increase in sickled erythrocytes. In vitro studies demonstrated a decrease in sickling of erythrocytes as a function of oxygen saturation of the blood when the patient was iron deficient. The whole blood oxygen dissociation curve showed a substantial decrease in oxygen pressure necessary to produce 50% saturation of hemoglobin at pH 7.4 and 37 degrees C (P50), indicating an increased oxygen affinity. These data suggest that a reduction of the MCHC induced by iron deficiency may ameliorate sickling.