BEYOND THE SOMATOPAUSE - GROWTH-HORMONE EFFICIENCY IN ADULTS OVER THEAGE OF 60 YEARS

GH secretion declines by 14%/decade of adult Life, leading to the sugg estion that people over the age of 60 yr are functionally GH deficient . If this is the case, one might not be able to detect a difference in GH secretion between the elderly with documented hypothalamic-pituita ry disease and an age-matched control group. We studied GH secretion i n 24 patients with hypothalamic-pituitary disease and 24 controls matc hed for body mass index and age using 24-h GH profiles, arginine stimu lation tests, and serum insulin-like growth factor I (IGF-I)levels. Th e median (range) area under the curve of the GH profile [<9.6 (<9.6-20 ) us. 18.5 (10.7-74.4) mu g/L 24 h; P < 0.0001], the median stimulated peak GH response to arginine [<0.4 (<0.4-7.7) vs. 8.0 (1.6-37.0) mu g /L; P < 0.0001], and the median serum IGF-I concentration [102 (<14-16 2) us. 147 (65-255) ng/mL; P = 0.0002] were significantly lower in the patients than in the controls. Fifteen patients showed no evidence of spontaneous or stimulated GH secretion, whereas all controls had evid ence of both. The area under the GH curve in the 33 subjects with demo nstrable GH secretion correlated significantly with the peak GH respon se to arginine (r = 0.71; P < 0.0001), but not with serum IGF-I concen tration. This study suggests that organic GH deficiency in the elderly is distinct from the decline in GH secretion associated with the agin g process. These patients may benefit from GH replacement therapy.