Spaceflight destroys red blood cells

Flight Engineer Anne McClain in the dome with biomedical equipment for MARROW. Credit: NASA

It’s true: space wants to kill us. And this time, space is trying to kill us from within.

A new study on astronauts living aboard the International Space Station shows that the astronauts’ bodies in space destroyed 54 percent more red blood cells than they normally would on Earth. Even a year after their flight and back to Earth, the symptoms of “space anemia” persisted in the 14 astronauts tested.

Astronaut anemia has been known to be a problem even since some of the first human missions to space. However, medical experts are unsure of the mechanisms that contribute to space anemia. For a long time, it was thought that space anemia was part of the fluid shift in astronauts when they arrive in space due to the zero-gravity conditions.

Upon entering microgravity, body fluids tend to migrate away from the legs to the upper body and head, with the usual result of nasal congestion, a feeling of fullness in the head and faces that appear swollen. This fluid shift has also been part of the investigations into why astronauts’ vision in space is declining.

Astronaut Tim Peake's first blood draw completed in space

Astronaut Tim Peake’s first blood draw in space completed. The sample was taken as part of the MARROW experiment. Credit: NASA

Previous studies showed that astronauts lose 10 percent of the fluid in their blood vessels as their bodies adjust to being in space. Those studies showed that vascular systems in the space environment quickly destroyed 10 percent of red blood cells to restore balance, and that red blood cell control returned to normal after 10 days in space.

Instead, a team led by Dr. Guy Trudel of the Ottawa Hospital and the University of Ottawa that red blood cell destruction was a primary effect of being in space, not just caused by fluid shifts. In addition, the rate of red blood cell destruction continued, albeit at a slower rate, for at least a year after the astronauts’ six-month expeditions into space.

“Here we show that spaceflight is associated with persistently elevated levels of products of hemoglobin breakdown, carbon monoxide in alveolar air, and iron in serum, in 14 astronauts during their 6-month missions aboard the International Space Station,” Trudel and his team wrote in their paper, published in Nature Medicine. “A year after landing, erythrocytic effects persisted, including increased levels of hemolysis, reticulocytosis and hemoglobin.”

Astronaut David Saint-Jacques collects samples

Astronaut David Saint-Jacques collects breath, ambient air and blood samples for the MARROW experiment. Credit: NASA

These findings, the team said, suggest that the destruction of red blood cells called hemolysis is a primary effect of microgravity during spaceflight and support the hypothesis that the anemia associated with spaceflight is a hemolytic condition that should be considered in the screening and monitoring of both astronauts and space tourists.

The destruction of red blood cells is constantly taking place in our body. On Earth, our bodies make and destroy 2 million red blood cells every second. The researchers found that astronauts’ bodies destroyed 54 percent more red blood cells during the six months they were in space, or 3 million per second. These results were the same for both female and male astronauts.

But the effects of this type of anemia won’t be apparent until the astronauts return to Earth.

Astronaut Jeff Williams collects breath sample

Astronaut Jeff Williams collects a breath sample for the MARROW experiment aboard the International Space Station. Credit: NASA

“Fortunately, having fewer red blood cells in space is not a problem when your body is weightless,” Trudel said in a press release. “But when you land on Earth and possibly other planets or moons, anemia that affects your energy, stamina and strength can threaten the mission objectives. The effects of anemia are not felt until you land, and you have to deal with gravity again.”

In this study, five of the 13 astronauts were clinically anemic when they landed – one of the 14 astronauts had no blood drawn on landing. While the researchers found that anemia slowly improved after a few months, even a year after the astronauts returned to Earth, red blood cell destruction was still 30 percent above pre-flight levels. The team said these results suggest that structural changes happened to the astronaut while they were in space, altering red blood cell control for up to a year after prolonged space missions.

What does this mean for future space travelers? Trudel’s team said anyone going to space should be screened for existing blood or health conditions affected by anemia. But also, since the study showed that the longer the space mission, the worse the anemia, it could affect long-term missions to the moon and (function(d, s, id){ var js, fjs = d.getElementsByTagName(s)[0]; if (d.getElementById(id)) return; js = d.createElement(s); js.id = id; js.src = "//connect.facebook.net/en_US/sdk.js#xfbml=1&version=v2.6"; fjs.parentNode.insertBefore(js, fjs); }(document, 'script', 'facebook-jssdk'));

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