Mon. May 23rd, 2022

Ottawa: A world-first study has revealed how space travel can cause lower red blood cell counts, known as rumanemia.

Analysis of 14 astronauts showed that their bodies destroyed 54 percent more red blood cells in space than they normally would on Earth, according to a study published in ‘Nature Medicine’.

“Rumanemia has been consistently reported since astronauts returned to Earth since the first space missions, but we did not know why,” said lead author Dr. Guy Trudel, a rehabilitation physician and researcher at Ottawa Hospital and professor at the University of Ottawa.

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“Our study shows that upon arrival in space, several red blood cells are destroyed, and this continues throughout the duration of the astronaut’s mission,” added Dr. Trudel.

Prior to this study, room anemia was considered to be a rapid adaptation to fluids that shifted into the astronaut’s upper body when they first arrived in space. Astronauts would lose 10 percent of the fluid in their blood vessels this way. It was believed that astronauts quickly destroyed 10 percent of their red blood cells to restore balance, and that control of red blood cells returned to normal after 10 days in space.

Instead, Dr. Trudel’s team found that the destruction of red blood cells was a primary effect of being in space, not just caused by fluid changes. They demonstrated this by directly measuring the destruction of red blood cells in 14 astronauts during their six-month space missions.

On Earth, our bodies create and destroy 2 million red blood cells every second. The researchers found that astronauts destroyed 54 percent more red blood cells during the six months they were in space, or 3 million every second. These results were the same for both female and male astronauts.

Dr. Trudel’s team made this discovery because of the techniques and methods they developed to accurately measure the destruction of red blood cells. These methods were then adapted to collect samples aboard the International Space Station.

At Dr. Trudel’s laboratory at the University of Ottawa, they were able to accurately measure the small amounts of carbon monoxide in the astronaut breath tests. One molecule of carbon monoxide was produced each time a molecule of heme, the deep red pigment in red blood cells, was destroyed.

While the team did not measure red blood cell production directly, they assumed that the astronauts generated extra red blood cells to compensate for the cells they destroyed. Otherwise, the astronauts would end up with severe anemia, and would have had major health problems in space.

“Fortunately, having fewer red blood cells in space is not a problem when your body is weightless,” said Dr. Trudel. “But when you land on Earth and potentially on other planets or moons, anemia that affects your energy, endurance and strength can threaten the mission’s goals. The effects of anemia are only felt when you land and have to deal with gravity again,” he said. .

In this study, five out of 13 astronauts were clinically anemic when they landed – one in 14 astronauts had not had a blood test on landing. The researchers saw that space-related anemia was reversible, with red blood cell levels gradually returning to normal three to four months after returning to Earth.

Interestingly, the team repeated the same measurements a year after the astronauts returned to Earth and found that the destruction of red blood cells was still 30 percent above pre-flight levels. These results suggest that structural changes may have occurred with the astronaut while in space, altering red blood cell control for up to a year after prolonged space missions.

The discovery that space travel increases the destruction of red blood cells had several implications. First, it supported the screening of astronauts or space tourists for pre-existing anemia or health conditions affected by anemia. Second, a recent study by Dr. Trudel’s team that the longer the space mission, the worse the anemia, which can affect long missions to the Moon and Mars. Third, increased red blood cell production would require an adapted diet for astronauts. And finally, it was unclear how long the body could maintain this higher rate of destruction and production of red blood cells.

These results can also be applied to life on Earth. As a rehabilitation doctor, most of Dr. Trudel’s patients anemic after being very ill for a long time with limited mobility, and anemia hampered their ability to exercise and recover. Bed rest had been shown to cause anemia, but how it did this was unknown.

“If we can find out exactly what causes this anemia, then there is a potential to treat it or prevent it, both for astronauts and for patients here on Earth,” said Dr. Trudel.

He was further quoted as saying: “This is the best description we have of control of red blood cells in space and after returning to Earth. These findings are spectacular, given that these measurements had never been made before and we had none “idea of ​​whether we should find something. We were surprised and rewarded for our curiosity.”

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