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Neocytolysis on Descent from Altitude: A Newly Recognized Mechanism for the Control of Red Cell Mass

Lawrence Rice, MD; Wilson Ruiz, MD; Theda Driscoll, CNT; Carl E. Whitley, MT; Rosario Tapia, BS; David L. Hachey, PhD; Gustavo F. Gonzales, MD; and Clarence P. Alfrey, MD
[+] Article and Author Information

From Baylor College of Medicine, Houston, Texas, and Universidad Peruana Cayetano Heredia, Lima, Peru.


Acknowledgments: The authors thank the following persons for essential technical and logistic support: Bertha Mendoza, Ruben Morcial Albiyor, Hortencia Carmelo, Mary Moir, Robert Talamini, Dr. Henry van Dyk, Dr. Holly van Dyk, and John Moulds. They also thank the volunteer participants for their cooperation.

Grant Support: By National Aeronautics and Space Administration grants NAGW 4993 and NASA/NSBRI NCC9-58.

Requests for Single Reprints: Lawrence Rice, MD, 6565 Fannin, MS 902-Main, Houston, TX 77030; e-mail, lrice@bcm.tmc.edu.

Current Author Addresses: Drs. Rice and Alfrey, Ms. Driscoll, and Mr. Whitley: Section of Hematology, Department of Medicine, Baylor College of Medicine, 6565 Fannin, MS 902-Main, Houston, TX 77030.

Drs. Ruiz and Gonzales and Ms. Tapia: Instituto de Investigaciones de la Altura, and Department of Physiological Sciences, Universidad Peruana Cayetano Heredia, Lima 1843, Peru.

Dr. Hachey: Department of Pharmacology, Vanderbilt University, 2201 West End Avenue, Nashville, TN 37232-6400.

Author Contributions: Conception and design: L. Rice, W. Ruiz, T. Driscoll, G.F. Gonzalez, C.P. Alfrey.

Analysis and interpretation of the data: L. Rice, T. Driscoll, C.E. Whitley, C.P. Alfrey.

Drafting of the article: L. Rice.

Critical revision of the article for important intellectual content: L. Rice, W. Ruiz, D.L. Hachey, G.F. Gonzalez, C.P. Alfrey.

Final approval of the article: L. Rice, W. Ruiz, T. Driscoll, C.E. Whitley, R. Tapia, D.L. Hachey, G.F. Gonzalez, C.P. Alfrey.

Provision of study materials or patients: W. Ruiz, R. Tapia, G.F. Gonzalez.

Statistical expertise: T. Driscoll.

Obtaining of funding: L. Rice, C.P. Alfrey.

Administrative, technical, or logistic support: W. Ruiz, T. Driscoll, C.E. Whitley, R. Tapia, D.L. Hachey, G.F. Gonzalez.

Collection and assembly of data: L. Rice, W. Ruiz, T. Driscoll, C.E. Whitley, R. Tapia, D.L. Hachey, C.P. Alfrey.


Ann Intern Med. 2001;134(8):652-656. doi:10.7326/0003-4819-134-8-200104170-00010
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Background: Studies of space-flight anemia have uncovered a physiologic process, neocytolysis, by which young red blood cells are selectively hemolyzed, allowing rapid adaptation when red cell mass is excessive for a new environment.

Objectives: 1] To confirm that neocytolysis occurs in another situation of acute plethora—when high-altitude dwellers with polycythemia descend to sea level; and 2) to clarify the role of erythropoietin suppression.

Design: Prospective observational and interventional study.

Setting: Cerro de Pasco (4380 m) and Lima (sea level), Peru.

Participants: Nine volunteers with polycythemia.

Interventions: Volunteers were transported to sea level; three received low-dose erythropoietin.

Measurements: Changes in red cell mass, hematocrit, hemoglobin concentration, reticulocyte count, ferritin level, serum erythropoietin, and enrichment of administered 13C in heme.

Results: In six participants, red cell mass decreased by 7% to 10% within a few days of descent; this decrease was mirrored by a rapid increase in serum ferritin level. Reticulocyte production did not decrease, a finding that establishes a hemolytic mechanism. 13C changes in circulating heme were consistent with hemolysis of young cells. Erythropoietin was suppressed, and administration of exogenous erythropoietin prevented the changes in red cell mass, serum ferritin level, and 13C-heme.

Conclusions: Neocytolysis and the role of erythropoietin are confirmed in persons with polycythemia who descend from high altitude. This may have implications that extend beyond space and altitude medicine to renal disease and other situations of erythropoietin suppression, hemolysis, and polycythemia.

Figures

Grahic Jump Location
Figure 1.
Change in red blood cell mass after descent from high altitude.51

Cr red cell mass at baseline and changes after 10 days at sea level are presented. White bars indicate participants who did not receive low-dose erythropoietin after descent; gray bars represent the volunteers who did receive low-dose erythropoietin. (Values for red cell mass determined by carbon monoxide rebreathing were almost identical.).

Grahic Jump Location
Grahic Jump Location
Figure 2.
Changes in serum ferritin values.rP

Serum ferritin values are plotted before and after descent from high altitude to sea level on day 11. The three white symbols represent different participants who received low-dose erythropoietin on descent; the other six symbols represent the participants who did not. The dotted line connects the mean values for the participants receiving erythropoietin, and the solid line connects the mean values for those who did not. Serum ferritin levels closely correlated with changes seen in red cell mass (Spearman coefficient, = 0.96;  < 0.01).

Grahic Jump Location

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Summary for Patients

A New Mechanism for Controlling the Number of Red Cells in the Blood

The summary below is from the full report titled “Neocytolysis on Descent from Altitude: A Newly Recognized Mechanism for the Control of Red Cell Mass.” It is in the 17 April 2001 issue of Annals of Internal Medicine (volume 134, pages 652-656). The authors are L Rice, W Ruiz, T Driscoll, CE Whitley, R Tapia, DL Hachey, GF Gonzales, and CP Alfrey.

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