The growth hormone (GH)/insulin-like growth factor axis plays a central role in the regulation of longitudinal growth.However,on closer inspection it is obvious that growth is regulated by several other known and unknown factors.Th.e growth response to GH treatment in short children is highly variable.Although the understanding of the mechanisms that modulate the growth response has evolved during the last decade,the reason for the varying response to GH treatment is largely unknown.Novel markers for the individual responsiveness to GH are still needed and the identification of more factors may increase our understanding on the regulation of longitudinal growth.Several strategies were developed to study regulation of growth.Growth hormone binding protein (GHBP),was studied and not found to predict growth response in a large cohort of children treated with GH.Results from studies on leptin,cartilage oligomeric matrix protein (COMP) and adiponectin will be discussed.