Hypothalamic-pituitary dysfunction in respiratory hypoxia.

Eight hypoxic male patients with stable chronic obstructive airways disease were submitted for combined anterior pituitary function testing. All subjects showed normal growth hormone and essentially normal cortisol responses to adequate hypoglycaemia, two subjects showed delayed responses of thyroid stimulating hormone to administered thyrotrophin releasing hormone and all had basal prolactin levels within normal limits. Basal levels of luteinising hormone were significantly lower than in the group of age-matched controls (p less than 0.02) but there was a normal increment after the injection of gonadotrophin releasing hormone. Basal levels of follicle stimulating hormone were significantly lower than in the controls (p less than 0.01), and there was also a reduced response from the pituitary after injection of gonadotrophin releasing hormone (p less than 0.01). Resting levels of the thyroid hormones thyroxine and tri-iodothyronine were normal while the expected subnormal testosterone level was observed (p less than 0.05). These results show that hypoxia can produce abnormalities of hypothalamic-pituitary function and that these are primarily located in the hypothalamic-pituitary-testicular axis.