IGF1 and Failure to thrive: In turn, in the GHD children with low IGF-I bioavailability and lower body mass, their thinness (for various reasons: silent gastrointestinal diseases, decreased level of neuropeptide-stimulating orexigenic axis, and children with failure to thrive) is accompanied by GHD (and is superimposed on GHD), which results in even more reduced IGF-I production.