Intraerythrocytic Adaptation to Anemia

The role of erythrocyte 2,3-diphosphoglycerate (2,3-DPG) in increasing the availability of hemoglobin oxygen in anemia was investigated. Measurements of 2,3-DPG and of oxygen dissociation (P50) were carried out on 57 normal subjects and 114 subjects with anemia. Twenty normal nonsmoking males had a mean hemoglobin of 15.3 g per 100 ml, a mean DPG of 4.83 mM and a mean P50 of 27.1 mm of mercury. Twenty normal nonsmoking females had a mean hemoglobin lower by 2.6 g per 100 ml, a DPG higher by 0.5 mM and a P50 increased by 0.4 mm of mercury DPG. P50 rose progressively with decreasing hemoglobin concentrations. For each gram of hemoglobin fall, there was a DPG increase of about 0.23 mM and a P50 increase of about 0.30 mm of mercury. Increases in adenosine triphosphate also occurred but, because of the smaller amount involved, had less effect on the oxygen dissociation curve. A rise in inorganic phosphate level had no demonstrable effect, but in vivo pH changes appear of considerable importance. It was calculated that DPG-induced changes in hemoglobin affinity for oxygen may compensate for up to half the oxygen deficit in anemia.