IGF1 and isolated congenital growth hormone deficiency: Nevertheless, to distinguish the last two conditions, we solely have available provocative GH tests and IGF-1, which present low evidence level and produce large amounts of false results (5, 6) The diagnosis of idiopathic GHD (IGHD) is established by stimulation tests of GH secretion, such as Insulin Tolerance Test (ITT) and the Clonidine Test (CT) (7, 8).