Erythrocyte 2,3-Diphosphoglycerate in Adaptive Red-Cell-Volume Deficiency

Measurement of red-cell volume, plasma volume and erythrocyte 2,3-diphosphoglycerate (2,3-DPG) in five patients with panhypopituitarism and one patient with isolated growth-hormone deficiency revealed marked decrease in the red-cell volume and plasma volume but no increase in the red-cell 2,3-DPG. The same studies performed in two hypophysectomized monkeys gave similar results. Administration of combined human growth hormone and thyroxine to one of the patients and to hypophysectomized monkeys resulted in increases of 45 to 88 per cent in 2,3-DPG within five weeks. The hormonal therapy also restored red-cell volume to normal. Further studies revealed that these calorigenic hormones acted synergetically to increase the concentration of erythrocyte 2,3-DPG. The findings suggest that the level of erythrocyte 2,3-DPG may be a useful guide to differentiate an "adaptive" from pathologic deficiency in red-cell mass.