Single and repeated testing of growth hormone secretory capacity in hypopituitarism using growth hormone releasing factor.

38 patients with proven growth hormone deficiency (GHD) and 19 children with familial short stature received an iv GRF-bolus injection of 1 microgram/kg body weight. Whereas in all control children plasma growth hormone rose significantly (mean of maximal values 36 ng/ml), only 7 out of 38 patients with GHD reached peak values of 8 ng/ml or more. GRF-priming by 1 microgram GRF/kg BW given once daily s.c. for 5 days in 19 patients improved the response of the pituitary gland in 11. Thus, following the first GRF test, only 21% of patients demonstrated function of the pituitary gland whereas 45% did so when all test results are combined. To evaluate the pituitary function in patients with GHD correctly, GRF tests following a GRF priming period seems to be necessary to reactivate atrophic somatotropic cells of the pituitary gland.