Insulin-like growth factor-I response is comparable following intravenous and subcutaneous administration of growth hormone

Subcutaneous (sq) administration of recombinant human growth hormone (r-hgh) has an anabolic effect and increases systemic insulin-like growth factor (IGF-I) in surgical patients. IGF-I is a mediator of growth hormone (gh) anabolic effects. To determine the effect of intravenous (iv) administration of r-hgh on systemic IGF-I, 11 patients were given 14 1-week courses of daily 8-hr infusions of r-hgh (10 mg in 500 ml D5W). Serum gh and IGF-I levels were measured. To compare routes of administration, iv r-hgh patients were matched to comparable sq r-hgh patients and IGF-I responses were examined. Illness severity effect on IGF-I response to r-hgh was assessed by dividing 16 burn patients who received either iv or sq r-hgh into two groups on the basis of severity scores. Analysis of the data showed that IGF-I levels increased significantly after iv r-hgh, IGF-I response to iv r-hgh (1.14 ± 0.18 U/ml to 4.12 ± 0.65 U/ml) was not different from IGF-I response to sq r-hgh (1.04 ± 0.36 U/ml to 4.96 ± 1.09 U/ml). Increasing illness severity attenuated the IGF-I response in the more severely injured group (0.91 ± 17 U/ml to 2.40 ± 0.38 U/ml) relative to the less severely injured group (1.37 ± 0.22 U/ml to 5.53 ± 0.78 U/ml) despite a significant increase in IGF-I after gh in both groups. In summary, IGF-I increased significantly after iv r-hgh and the increases were similar to those seen after sq r-hgh in comparable patients. Increasing severity of illness attenuated the IGF-I response to r-hgh given either iv or sq in burn patients.