Abstract
To asses the age-related change of growth hormone (GH) secretion in man, blood GH levels on insulin tolerance test, arginine infusion test and blood sumples on early sleeping time were assayed in normal elderly subjects (over aged 60) and young subjects (aged 15 to 35) .
The fasting and maximal levels in both insulin and arginine tests were not significantly altered with aging. To insulin tolerance test, the mean maximal level of whole subjects was on 60 minuites, but 2 of 8 young subjects reached on 30 minuites, while 1 of 8 elderly subjects did on 120 minuites.
On time of decreasing phase of blood GH response, the mean GH levels of elderly subjects remained markedly higher than those of young subjects on 120 and 180 minuites after insulin puls and on 120 minuites after arginine infusion. These prolongation in elderly subjects of reaching to maximal value and returnning to basal value were suspected one of specific reactions of the elderly tested their hormonal function.
Measurring sleep-related GH secretion, 4 of 9 young subjects showed higher blood GH levels than 5 ng/ml which proposed upper limitt of normal basal value, while all of 10 elderly subjects remained low level under 5 ng/ml.
Young and elderly corticosteroid-treated patients whose total dosages of corticosteroids under 5000 mg (prednisolone base) were respected to keep normal GH function by measurring maximal levels on insulin tolerance tests. But the patients whose total dosages over 5000 mg declined GH function, especialy elderly patients suposed to be markedly affected reflecting to their mean maximal level of 8.8±3.0 ng/ml which was less than lower limitt of normal maximal GH value (10 ng/ml) by insulin tolerance test.
