Effects of various hyperbaric gas mixtures on hormonal parameters of healthy human blood and saliva

Changes in some hormonal parameters of healthy subjects were studied during experimental 3- to 18-day dives in hyperoxic (oxygen-nitrogen-helium) and argon-containing (normoxic and hyperoxic) gas mixtures. The blood levels of growth hormone, corticotropin, thyrotropin (TSH), thyroid hormones, total cortisol, insulin, and C-peptide, as well as the total salivary free cortisol, were measured during and after hyperbaric exposure. In most cases, the changes in these parameters did not exceed normal clinical and individual ranges. A statistically significant increase in the total cortisol and blood TSH were detected during the exposure to hypoxic oxygen-nitrogen and oxygen-nitrogen-argon mixtures. The time course of salivary free cortisol indicated the most stressful periods of the experimental exposures.