Reference values of blood biochemical indices in Russian cosmonauts

In the period from 2000 to 2012, the values of 40 diagnostically significant biochemical indices in venous blood were determined during the preflight clinical and physiological examination of 28 Russian cosmonauts aged 35 to 54, members of the main and backup crews of missions on board the International Space Station. The examination was conducted 45-30 days prior to the launch. Since most cosmonauts performed several flights during this period and they were repeatedly included in backup crews, each of the cosmonauts participated in preflight examinations one to five times. The reference values were calculated for each of the studied indices. It was found that reference interval boundaries for 15 indices were narrower as compared to the generally accepted ranges. The upper boundaries of the reference ranges of the activities of a number of enzymes, as well as of the concentrations of some metabolites of energy and plasticity metabolism, were higher than the population’s mean values. Thus, it was found that Russian cosmonauts, being a specific professional team, had reference values of a number of blood biochemical indices that were different from the population’s mean values. This was due to the characteristics of selection, physical training, and psychic and emotional states of crew members during the preflight period.