The effect of stressful diagnostic studies and surgery on anterior pituitary hormone release in man

The hormonal response of the anterior pituitary was studied in 10 normal males undergoing treadmill exercise testing, in 5 male patients undergoing diagnostic gastroscopy, and in 8 male patients undergoing elective surgery under general anaesthesia. Serum TSH was depressed below the baseline value at 2 and 3 h post-treadmill exercise, at 1, 2 and 3 h post-gastroscopy and from 10 min through 2 h post-surgery. Serum triiodothyronine was depressed below the baseline value at 10 min through 2 h post-surgery. Serum prolactin, growth hormone and cortisol were elevated by all three stressful procedures. Both gastroscopy and surgery resulted in an elevation of serum luteinizing hormone levels. There was no significant change in serum FSH levels in any of the three procedures. The post-stress depression in TSH levels could result from the suppressive effect at the hypothalamic-pituitary level of high serum levels of cortisol generated by the stress of the procedures.