here you go. i actually do have the study and reference here.
Beneficial Effects of Extended Growth Hormone Treatment After Hospital Discharge in Pediatric Burn Patients
Rene Przkora, MD, PhD, David N. Herndon, MD, Oscar E. Suman, PhD, Marc G. Jeschke, MD, PhD, Walter J. Meyer, MD, David L. Chinkes, PhD, Ronald P. Mlcak, PhD, Ted Huang, MD, and Robert E. Barrow, PhD
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annals of surgery pub med
The serum hormone panel provides indications as how the effects of rhGH might be mediated. One proposed mechanism of action of rhGH is through stimulation of hepatic production of IGF-1 and its binding protein IGFBP-3.13 This is supported by our results in which serum growth hormone, IGF-1, and IGFBP-3 were significantly elevated compared with placebo. After discontinuing treatment 12 months after burn, serum concentrations of growth hormone and IGFBP-3 were no longer significantly different compared with placebo. Interestingly, IGF-1 was still significantly elevated at 18 months after burn, at a time when rhGH had been discontinued for 6 months. Elevated levels of IGF-1 may reflect an additional production induced by the increased LBM in those children who received rhGH.24 The compliance of patients receiving rhGH injections at home has been correlated to IGF-1 serum levels.25 Besides the elevation of endogenous anabolic hormones, rhGH significantly reduced serum cortisol concentrations, which is a known mediator of catabolic reactions.26,27 This decrease in cortisol was observed during rhGH treatment as well as in the following year after the drug was discontinued. The significant increase of osteocalcin, a marker for bone turnover, at 18 months after burn in those receiving rhGH may be associated with the increase in height and BMC in the second year of the study relative to placebo. The nutritional intake was not different between groups; thus, we attribute these findings to the effect of rhGH. Adverse side effects associated with anabolic therapy such as glucose intolerance, precocious sexual development, or early epiphysial closure were not noted at follow-up visits.
like i said before to make it simple, gh serum is decreased after use, however igf 1 remains elevated for 18 months.