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Canadian Scientists May Have Discovered Why Astronauts Suffer from ‘Space Anemia’

Study conducted on International Space Station found crew’s red blood cells were destroyed 54% faster in space than while on Earth

Hemolysis in blood specimens is something that clinical laboratories deal with every day. Now researchers in Canada have determined that, while astronauts are in space, hemolysis is a causative factor in the condition known as “space anemia.”

Hematologists whose clinical laboratories process a steady volume of complete blood count (CBC) tests to diagnosis anemia will want to take note of this research study, which was conducted at the University of Ottawa and on the International Space Station. Dubbed the “MARROW” study, it may have uncovered not only why astronauts suffer from anemia even a year after returning to Earth, but also how those insights can be applied to treatments for anemia and other blood diseases for Earthbound patients as well.

Anemia is caused by a marked decrease in the number of red blood cells and can lead to weakness, persistent fatigue, and slower brain function, which on Earth is concerning, but in space can be life threatening.

“Space anemia has consistently been reported when astronauts returned to Earth since the first space missions, but we didn’t know why,” said the study’s lead author Guy Trudel, MD, in a University of Ottawa news release.

Trudel is Director of the Bone and Joint Research Laboratory at the Ottawa Hospital Rehabilitation Centre in Canada. He is also a Rehabilitation Physician and Researcher at the Ottawa Hospital and Professor of Medicine at the University of Ottawa, and the principal investigator of the MARROW study, which is investigating the effects of microgravity on bone marrow, according to NASA.

“Our study shows that upon arriving in space, more red blood cells are destroyed, and this continues for the entire duration of the astronaut’s mission,” he added.

Although these scientific findings may not immediately lead to new methodologies for testing human blood for use in clinical laboratories, the insights gleaned from the study could inform future studies designed to learn how to get the body to produce more red blood cells in ways that benefit patients diagnosed with anemia or other blood disorders.

The scientists published their findings in the journal Nature Medicine, titled, “Hemolysis Contributes to Anemia During Long-Duration Space Flight.”

Guy Trudel, MD

Guy Trudel, MD (above), Rehabilitation Physician and Researcher at the Ottawa Hospital and Professor at the University of Ottawa, is lead author of a Canadian study explaining why astronauts develop “space anemia.” In space, astronauts’ red blood cells are destroyed 54% faster than while on Earth, a finding that could have implications for space tourists and astronauts on longer missions to the moon and Mars, the researchers noted. (Photo copyright: University of Ottawa.)

Effects of Anemia Continue One Year after Returning to Earth

The MARROW research project, which was funded by the Canadian Space Agency (CSA), required the participation of 14 astronauts on the International Space Station.

The researchers began collecting data in October 2015 and completed their final tests in June 2020. They found that astronauts’ bodies destroyed 54% more red blood cells in space than would be normal on Earth, according to the study published in Nature Medicine.

“Thankfully, having fewer red blood cells in space isn’t a problem when your body is weightless,” Trudel said in the news release. “But when landing on Earth, and potentially on other planets or moons, anemia affecting your energy, endurance, and strength can threaten mission objectives. The effects of anemia are felt once you land and must deal with gravity again.”

The MARROW experiment detected the following changes:

  • During a six-month mission, astronauts’ bodies were destroying 54% more red blood cells than typical preflight rates.
  • Five of the 13 astronauts who had their blood drawn shortly after landing back on Earth were anemic. Red blood cell levels gradually improved three to four months post-flight.
  • The rate of red blood cell destruction remained 30% higher one year after landing than before missions to the International Space Station.

“Increased hemolysis as a primary effect of exposure to space constitutes a paradigm shift in our understanding of space anemia … Persistent hemolysis during space missions suggests that the longer the exposure, the worse the anemia,” the study’s authors wrote.

Measurements were made by testing the astronauts’ blood for iron levels and using breath tests to measure exhaled carbon monoxide. One molecule of carbon monoxide is produced every time one molecule of heme, the deep-red pigment in blood cells, is destroyed.

According to the researchers, the discovery that space travel increases red blood cell destruction:

  • highlights the need to screen astronauts and space tourists for existing blood or health conditions that are affected by anemia;
  • impacts longer missions to the moon and Mars, which would likely worsen an astronaut’s anemia;
  • suggests astronauts require an adapted diet; and
  • shows it is unclear how long the body can maintain this higher rate of destruction and production of red blood cells.

Space Study Could Lead to Better Healthcare on Earth

A 2007 NASA study published in Microgravity Science and Technology blamed space anemia on water loss during space flight decreasing the amount of hemoglobin in red blood cells. The study labeled space anemia a “15-day ailment” because those researchers believed issues resolved within 15 days of crew members returning to Earth.

The MARROW study, however, found much longer-lasting implications for astronauts in space, which could lead to new insights for patients on Earth. The Canadian Space Agency believes the study’s findings could lead to better understanding and monitoring of the effects of physical inactivity on seniors, bedridden patients, and those with reduced mobility or undergoing rehabilitation.

“The findings have implications for understanding the physiological consequences of space flight and anemia in patients on the ground,” Sulekha Anand, PhD, a professor in the Department of Biological Sciences at San Jose State University, told Reuters.

This latest study shows how discoveries in space continue to lead to advancements in scientists’ understanding of how the human body functions. That knowledge may one day provide the foundation for developing new or improved clinical laboratory tests for astronauts as well as everyday earthlings.

Andrea Downing Peck

Related Information:

New Canadian-led Study Shows Why Astronauts Are Anemic When Returning from Space Travel

We Finally Know the True Extent of Space Destroying Astronauts’ Red Blood Cells

Hemolysis Contributes to Anemia During Long-Duration Space Flight

Anemia in Astronauts Could Be a Challenge for Space Missions

Blood and Oxidative Stress (BOS): Soyuz mission “Eneide.”