Abstract
In order to study the hypothalamo-pituitary adrenocortical response to stress stimuli, an increase of plasma 11-OHCS during insulin induced hypoglycemia was determined by De Moor's method and the result was compared with that of metopirone test in 4 control subjects and 69 patients with miscellaneous endocrine diseases.
(1) 2 cases out of 13 patients with pituitary chromophobe adenoma and 3 cases out of 23 patients with operated chromophobe adenoma showed no response to hypoglycemia. And also in craniopharyngiomas, one case among 5 patients before operation and one among 5 post operated patients failed to respond to hypoglycemia. Therefore, the pituitary adrenocortical response in insulin induced hypoglycemia was not affected unless hypothalamo-pituitary system was impared severely, while metopirone test was most sensitive for the detection of defects in ACTH secretion throughout the hypothalamo-pituitary system and was very effective to detect even slight disturbances in pituitary ACTH reserve, though it represents only one aspect of the reserve. Therefore, it is suggested that this “insulin stress” test may be taken as a true measure of total ACTH reserve.
(2) In 5 acromegalies, 2 cases associated with moderate hyperthyroidism and treated with 131I did not respond either to hypoglycemic stress or to metopirone. And in 5 thyrotoxic patients including 2 cases with a aromegaly previously described, only those 2 cases showed no response. Accordingly, coexistence of both the disease seemed to cause the failure of response to hypoglycemia.
(3) 5 cases among 6 patients with Cushing's syndrome showed no response to insulin induced hypoglycemia and one case poorly responded. And this effect was independent of the initial value of plasma 11-OHCS. As 3 cases with adrenal hyperplasia had nor-mal or subnormal response to Metopirone, this absent response to hypoglycemia may be due to the inability of hypothalamo-pituitary system to synthesize and secrete endogenous ACTH immediately in emergency. On the other hand, 3 cases with adrenal adenoma did not respond either to Metopirone or to hypolgycemia. This mechadism is perhaps referred to the inhibitory effect of endogenous corticosteroids from adenoma for hypothalmo-pituitary system to secrete endogenous ACTH.
(4) This “insulin stress” test is easy to perform and almost free from hazardous trouble. And consequently, it is very effective to detect the disturbances of total pituitary ACTH reserve. Protection from stressful stimuli and prophylactic administration of corticosteroids are recommended for the patients who have no response or disturbed response to insulin induced hypoglycemia.
