This phenomenon, called space anemia, has been well-studied. It’s part of a suite of problems that astronauts face when they come back to terra firma, which is how Guy Trudel — one of the paper’s authors and a specialist in physical medicine and rehabilitation at The Ottawa Hospital — got involved. “[W]hen the astronauts return from space, they are very much like the patients we admit in rehab,” he told Ars. Space anemia had been viewed as an adaptation to shifting fluids in the astronauts’ upper bodies when they first arrive in space. They rapidly lose 10 percent of the liquid in their blood vessels, and it was expected that their bodies destroyed a matching 10 percent of red blood cells to get things back into balance. People also suspected that things went back to normal after 10 days. Trudel and his team found, however, that the hemolysis was a primary response to being in space. “Our results were a bit of a surprise,” he said. […]
Trudel’s team isn’t sure exactly why being in space would cause the human body to destroy blood cells at this faster rate. There are some potential culprits, however. Hemolysis can happen in four different parts of the body: the bone marrow (where red blood cells are made), the blood vessels, the liver, or the spleen. From this list, Trudel suspects that the bone marrow or the spleen are the most likely problem areas, and his team has plans to investigate the issue further in the future. “What causes the anemia is the hemolysis, but what causes the hemolysis is the next step,” he said. It’s also uncertain how long a person in space can continue to destroy 54 percent more red blood cells than their Earth-bound kin. “We don’t have data beyond six months. There’s a knowledge gap for longer missions, for one-year missions, or missions to the Moon or Mars or other bodies,” he said.
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