Growth hormone (GH) is known to have direct action on long bone growth in children, but majority of its anabolic and metabolic actions are mediated through intermediary factors like IGFBP 3 & IGF-1. GH deficiency is mostly idiopathic in children whereas Pituitary adenoma is the commonest cause in adults. IGF-1 levels are useful in diagnosing patients with active Acromegaly with low basal GH levels & in suspected cases of Acromegaly who show suppression of GH to normal after glucose administration. IGFBP-3 is used in the differential diagnosis of GH deficiency and Non-GH deficient short children. It is also used to assess nutritional status.