Morphofunctional Status of Astronauts’ Erythrocytes after Missions to the International Space Station of Varying Duration

Forty ISS male astronauts at the age of 36 to 61 years participated in investigations of the hematological parameters and erythrocyte indices including those used to detect a latent iron deficit (MAF, LHD%). The astronauts were divided into three groups. Group 1 consisted of nine astronauts who had made 8 to 14‑day missions; Group 2 consisted of 27 astronauts whose mission duration was 125 to 215 days; Group 3 consisted of four astronauts who had accomplished 355 to 371-day long missions. The data show that post-recovery changes of the erythrocyte morphofunctional properties are compensatory and aimed to overcome the stress from re-adaptation to Earth’s gravity. Missions of 8−14-d duration do not affect erythrocytes dramatically. After 125–215-d and 355–371-d missions we observed signs of a hypochromic anemic syndrome that depended on length of life in microgravity. Irrespective of mission duration, the width of erythrocyte distribution by volume decreases considerably during early recovery which implies reduction of heterogeneity in the erythrocyte population.