Alterations in hematologic indices during long-duration spaceflight

Hawley KunzView ORCID ID profile,
Heather Quiriarte,
Richard J. Simpson,
Robert Ploutz-Snyder,
Kathleen McMonigal,
Clarence Sams and
Brian CrucianEmail author

BMC HematologyBMC series – open, inclusive and trusted201717:12

https://doi.org/10.1186/s12878-017-0083-y

Received: 20 January 2017

Accepted: 8 August 2017

Published: 8 September 2017

Open Peer Review reports

Abstract

Background

Although a state of anemia is perceived to be associated with spaceflight, to date a peripheral blood hematologic assessment of red blood cell (RBC) indices has not been performed during long-duration space missions.

Methods

This investigation collected whole blood samples from astronauts participating in up to 6-months orbital spaceflight, and returned those samples (ambient storage) to Earth for analysis. As samples were always collected near undock of a returning vehicle, the delay from collection to analysis never exceeded 48 h. As a subset of a larger immunologic investigation, a complete blood count was performed. A parallel stability study of the effect of a 48 h delay on these parameters assisted interpretation of the in-flight data.

Results

We report that the RBC and hemoglobin were significantly elevated during flight, both parameters deemed stable through the delay of sample return. Although the stability data showed hematocrit to be mildly elevated at +48 h, there was an in-flight increase in hematocrit that was ~3-fold higher in magnitude than the anticipated increase due to the delay in processing.

Conclusions

While susceptible to the possible influence of dehydration or plasma volume alterations, these results suggest astronauts do not develop persistent anemia during spaceflight.