Oxygen deficiency encountered at high altitude may lead to clinical or sub clinical symptoms because of unsuccessful acclimatization. The aim of the project is to study the effects of extreme altitude, which may persist for short or long term periods after the armed forces personnel are de-inducted to plains from high altitude areas.

Studies were carried out on 300 subjects in the age group of 20 – 35 yrs 5, 30, 60 and 90 days after de-induction from extreme altitudes of 5700 to 6100 m. Another group of subjects who have never been to high altitude served as a control. A battery of tests was used to evaluate their physiological and biochemical profile.

The autonomic profile in terms of sympathetic and parasympathetic activity and reactivity was measured. The results indicate increased sympathetic reactivity and decrease in parasympathetic reactivity after six days of de-induction as compared to the control subjects. With increase in time of de-induction, these parameters return to normal values.

Semen samples were collected and analyzed for volume, consistency, pH, sperm count, hypo-osmotic swelling test, progressive motility, viability, morphology. There were variations in the values of the above parameters. However, these values were within the normal range. No significant reduction in testosterone was observed after 5th day of de-induction from HA as compared to 30, 60 and 90 days after return to SL. No definite pattern of change was observed in Estradiol levels.

Total protein, HDL, LDL, total cholestrol, estradiol, liver function tests kidney function tests were done in blood samples drawn after overnight fast. Blood haemoglobin levels were also estimated. Results indicate increased haemoglobin level and higher serum total protein on 5th day of induction, normal levels in group studied at 30, 60 and 90 days after de-induction. Levels of aspartate amino transferase , alanine aminotransferase and °- glutamyl transpeptidase were within the normal range and indicated no abnormality in liver and cardiac functions. Significantly low levels of total cholestrol in subjects on 5th day of de-induction from HA was seen. All the biochemical parameters regressed to normal levels within a month after de-induction from HA.

The induction to HA results in certain physiological and biochemical adjustments in the system in order to withstand the altitude stress. The changes are regressible in nature on de-induction to sea level and within 90 days the effect of HA stay return to basal values.