RT Book, Section A1 Thiagarajan, Perumal A1 Prchal, Josef A2 Kaushansky, Kenneth A2 Lichtman, Marshall A. A2 Prchal, Josef T. A2 Levi, Marcel M. A2 Press, Oliver W. A2 Burns, Linda J. A2 Caligiuri, Michael SR Print(0) ID 1121091498 T1 Erythrocyte Turnover T2 Williams Hematology, 9e YR 2015 FD 2015 PB McGraw-Hill Education PP New York, NY SN 9780071833004 LK hemonc.mhmedical.com/content.aspx?aid=1121091498 RD 2024/04/20 AB SUMMARYThe survival of red cells in the circulation can be measured in a variety of ways: (1) by labeling with radioactive isotopes, particularly chromium-51 (51Cr), and assessing the disappearance of the radioactive tag from the circulation over time; (2) by labeling the erythrocytes with biotin or a fluorescent dye and measuring this marker over time; (3) by determining the disappearance of transfused antigen-matched allogeneic erythrocytes using immunologic markers; and (4) by measuring the excretion of carbon monoxide, a product of heme catabolism.Such studies show that normal human red cells have a finite life span averaging 120 days, with very little random destruction. The mitochondrial and ribosomal removal highlighting maturation of the reticulocyte is accompanied by increasing cell density, but after a few days of intravascular life span there is little further increase in density or other changes in the physical property of the red cells. Thus, cell density is not a good marker for aged red cells. This has made the senescent changes in the red cell that mark it for destruction difficult to study. Candidates for such changes include changes in membrane band 3 and exposure of phosphatidylserine on the membrane, which may be of major importance.