The diagnosis of GHD requires GH-stimulation tests, except for patients affected by: i) organic hypothalamic–pituitary disease with ≥ 3 pituitary hormone deficiencies and serum IGF-I levels < − 2.0 SDS; ii) genetic defects of the hypothalamic–pituitary axes; iii) hypothalamic–pituitary structural brain defects, in which additional tests are not necessary [3]. This evidence concerns the gene GH1 and pituitary gland disorder.