We don’t know why, but being in space causes us to destroy our blood

We don't know why, but being in space makes us destroy our own blood

Space is not easy for humans. Some aspects are avoidable – vacuum of course, cold, as well as some radiation. Astronauts can also lose bone density due to a lack of gravity. NASA even created a fun acronym for issues: RIDGE, which stands for space radiation, isolation and confinement, distance from Earth, gravitational fields, and hostile and closed environments.

New research adds to concerns by describing how being in space destroys your blood. Or rather, something about space – and we don’t know what’s going on yet – causing the human body to hemolysis at a higher rate than it does on Earth.

This phenomenon, called anaemia, has been well studied. It’s part of a range of problems astronauts face when they return to Verma Earth, which Guy Trudel – one of the paper’s authors and a physical medicine and rehabilitation specialist at Ottawa Hospital – shared. “[W]When the astronauts return from space, they look a lot like the patients we get into rehab.”

Anemia in space was seen as an adaptation to shifting fluids in the upper body of astronauts when they first arrived in space. They rapidly lose 10 percent of the fluid in their blood vessels, and their bodies were expected to destroy 10 percent of their red blood cells to bring things back into balance. People also suspected that things were back to normal after 10 days. Trudel and his team found, however, that hemolysis was an essential response to being in space. “Our results were a bit of a surprise,” he said.

In space, no one can hear you breathe in a can

To study anemia in space, Trudel worked with 14 astronauts on a six-month mission on the International Space Station. The astronauts brought in specialized packs and exhaled into them at four set intervals: five days, 12 days, three months, and before returning home at six months. Then, with their primary mission over, they returned the packs to the ground, their breaths and everything.

Back in the lab, the researchers looked at the astronauts’ breath using a high-resolution gas chromatograph, which measures how much carbon monoxide they were producing after different periods of time in space. According to Trudel, carbon monoxide is created every time red blood cells are broken down in the body. This is not a perfect connection, as other bodily processes can lead to carbon monoxide production, such as certain muscle and liver functions. However, Trudel noted that an estimated 85 percent of the carbon monoxide produced by humans comes from hemolysis.

The team’s results showed that in space, astronauts’ bodies destroyed about 3 million red blood cells every second. This is 54 percent higher than what happens in human bodies on Earth, at a rate of 2 million every second.

In space, the human body loses fluid, so even though the astronaut’s body ends up with fewer red blood cells, the concentration stays at acceptable levels. But when humans return to Earth, their bodies regain fluids to counteract the increase in gravity, and space-time anemia begins. “You need more fluid in your blood vessels, and that would dilute your red blood cells,” he said.

After the astronauts returned from their flight, five of the 13 who had blood drawn upon landing were still clinically anemic. After three or four months, the number of red blood cells continues to grow. However, Trudel’s team performed the same test a year later and found that red blood cell destruction was still 30 percent higher in astronauts. According to the researcher, the longer astronauts stay in space, the longer they will develop anemia in space on solid Earth.

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