Rapid effect of intravenous growth hormone (GH)-releasing hormone 1-44 on plasma GH levels in children.

Growth hormone releasing hormone (GHRH)-testing was performed in 24 short normal children (16 male, 8 female). Before and after administration of GHRH1-44 (1 microgram/kg body weight i.v.) blood samples for growth hormone (GH) determination were drawn at -30, 0, 1, 2, 3, 4, 6, 8, 10, 15, 30, 45, 60, and 90 min. Plasma GH increase was apparent 1 min after injection and in 12 patients (7 female) peak plasma GH values were reached within 15 min. In all patients plasma GH levels were greater than 10 ng/ml within the first 8 min following GHRH injection, but in 4 patients this level was not attained when considering only GH values obtained after 15 min. These results demonstrate the capability of the pituitary to rapidly secrete GH in response to GHRH1-44 in children. Therefore, in this age group blood samples for GH determination should be taken earlier when testing with GHRH1-44.