IGF1 and Crohn disease: Young patients with Crohn's disease and growth impairment, despite a normal stimulation and spontaneous secretion of GH, have a reduced plasmatic concentration of insulin type-1 growth factor (IGF-1), which suggests resistance to GH.[5] The imbalance between GH and IGF-1 may be explained in part by the action of interleukin-6 (IL-6).[6]