Influence Of Altitude Hypoxia In Physiological Mechanisms Of Human Male Fertility.

Introduction: Spermatogenesis is one of the most delicate processes occurring in reproduction. Many studies suggest that exposure of normoxia-native individuals to hypoxia can affect spermatogenesis. The aim of this study was to evaluate the effect of chronic altitude hypoxia on human male reproductive functions. Methods: Seven healthy subjects climbed for 13 days in an acclimatization trek until they reached Manaslu Base Camp (5000 m) for spending 22 days at high altitude. The climbers slept 2 nights in camp 1 (5900 m) and, finally, after some failed attempts to climb to camp 2 (6400 m), returned to Katmandu in 8 days. Before and after the expedition, a number of seminological parameters (SP) were analysed: volume, total sperm number, sperm count, motility, % of sperm with normal morphology, total number of motile sperm. Before and after the expedition at sea-level (sl), after 10 days at sl and 6 months from the expedition return at sl, the serum levels of T, FSH, LH, PRL, 17β-E2, cortisol, FT3, FT4, TSH were assessed. P< 0.05 was considered statistically significant. Results: Volume, total number, total number of motile spermatozoa and sperm count was found to be reduced after return to sl. T increased 10 days after, returning to pre-values at 6 months follow-up. FSH increased after return as a result of high altitude experience, with return to pre-expedition value after 10 days. LH increased after return to sl, with recovery 6 months after. The 17β-E2 decreased after return with recover trend 10 days after and with total recovery at 6 months. PRL increased after return, at 10 days, with recovery at 6 months. Decrease of FT3 and increase of FT4 at the end of expedition, with recovery after 10 days. Conclusions: Hypoxic experience induced negative effects on male fertility occurring through the reduction of important SP, thus suggesting the influence of oxygen supply in physiological mechanisms of spermatogenesis. Furthermore, this study shows that prolonged altitude exercise is related to an adaptation of the endocrine system.