The Measure of Erythropoiesis in Anemias. II. The Immediate and Subsequent Loss of Transfused Erythrocytes in Healthy Subjects

1. Fresh and stored red cells, transfused in healthy subjects, disappear from the circulation during the first 24 hours at a rate in excess of that prevailing in subsequent 24 hour periods. When fresh red cells are transfused the excess first day loss is approximately 3 per cent.

2. Comparative survival studies using the nonagglutinable red cell method of Ashby have indicated that this excess immediate loss is not due to elution of Cr⁵¹, but to actual loss of red cells.

3. When red cells are stored improperly or for an extended period of time, the excess loss occurs very rapidly, and at one hour is approximately 50 per cent of the total loss at 24 hours. The limitations to the use of the dilution data of transfused stored cells to establish the 100 per cent value for the measure of the survival of the transfused red cells are implicit.

4. When the first 24 hour loss of transfused red cells is approximately 30 per cent or more, paradoxically the rate of loss in subsequent days is less than when fresh, undamaged red cells are transfused. This observation raises the question of interpretation of the measure of the red cell survival expressed as T ½.