Space anemiaposes a significant risk to deconditioning, and should be considered as spacetourism becomes more popular and available, according to a paper published inthe American Journal of Hematology.1

Space travelrelated anemia has been a concern for the past 60 years, though conflicting data have prevented researchers from determining, with certainty, that being in space can directly lead to the condition. Researchers determined that evaluating hemoglobin (Hb) concentrations and red blood cell (RBC) mass within 7 days of returning to Earth from space would, however, be sufficient for determining any link.

For this study,the authors evaluated data recorded in the National Aeronautics and SpaceAdministrations Lyndon B. Johnson Space Centers system, which containsrecords for all astronauts since the programs inception, to determine anycausal relationship between space travel and changes in Hb concentrations.

Two datasetswere included, the first of which contained records from 711 mission-astronautswith 1962 Hb measurements and 721 mission-astronauts with 17,336 Hbmeasurements. All data were compared with those from control records taken atthe time of each mission.

Forty-eightpercent of astronauts were anemic when they returned to Earth after spacetravel. Longer trips to space also appeared to require more recovery time afterthe journey than did shorter trips, with Hb levels returning to normal after 49days for trips of 11.5 to 145 days vs 24 days for trips of a mean of 5.4 days.

Astronauts whosetrips lasted 5.4 days, 11.5 days, and 145 days had Hb decrements of -0.61 g/dL(4%), -0.82 g/dL (5%), and -1.66 g/dL (11%), respectively.

Wecharacterized space anemia, its dose-response relationship with exposure to spaceas well as longitudinal effects, the authors wrote. Whether acute spaceanemia will turn into chronic anemia depends critically on the duration ofexposure to space.

Reference

Trudel G, Shafer J, Laneuville O, Ramsay T. Characterizing the effect of exposure to microgravity on anemia: more space is worse. Am J Hematol. 2020;95(3):267-273.

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Anemia in Space: Implications for Space Travel and Tourism - Hematology Advisor