If early catch-up growth does not occur and their heights remain below the third percentile by 2 or 3 years of age, adult height is likely to be similarly low. High-dose GH treatment has been shown to accelerate growth, but data on long term benefits and risks are limited. Idiopathic short stature (ISS) is one of the most controversial indications for GH as pediatric endocrinologists do not agree on its definition, diagnostic criteria, or limits. The term has been applied to children with severe unexplained shortness that will result in an adult height below the 3rd percentile. In the late 1990s, the pharmaceutical manufacturer Eli Lilly and Company sponsored trials of their brand of rHGH (Humatrope) in children with extreme ISS, those at least 2.25 standard deviations below mean (in the lowest 1.2 percent of the population). These boys and girls appeared to be headed toward heights of less than 63" (160 cm) and 59" (150 cm) respectively. They were treated for about 4 years and gained 1.5–3 in (3.8–7.6 cm) in adult height. Controversy has arisen as to whether all of these children were truly "short normal" children, since the average IGF1 was low. Approval of HGH for the treatment of this extreme degree of shortness led to an increase in the number of parents seeking its use to make otherwise normal children a little taller.
Adverse effects
The New England Journal of Medicine published two editorials in 2003 expressing concern about off-label uses of HGH and the proliferation of advertisements for "HGH-Releasing" dietary supplements, and emphasized that there is no evidence that use of HGH in healthy adults or in geriatric patients is safe and effective – and especially emphasized that risks of long-term HGH treatment are unknown. One editorial was by Jeffrey M. Drazen, M.D., the editor-in-chief of the journal; the other one was by Dr. Mary Lee Vance, who provided the NEJMs editorial original, cautious comment on a much cited 1990 study on the use of HGH in geriatric patients with low growth hormone levels.A small but controlled study of GH given to severely ill adults in an intensive care unit setting for the purpose of increasing strength and reducing the muscle wasting of critical illness showed a higher mortality rate for the patients having received GH. The reason is unknown, but GH is now rarely used in ICU patients unless they have severe growth hormone deficiency.GH treatment usually decreases insulin sensitivity, but some studies showed no evidence for increased diabetes incidence in GH-treated adult hypopituitary patients.In past it was believed that GH treatment could increase the cancer risk; a large study recently concluded that "With relatively short follow-up, the overall primary cancer risk in 6840 patients receiving GH as adults was not increased. Elevated SIRs (which is risk of getting cancer) were found for subgroups in the USA cohort defined by age <35 years or childhood onset GH deficiency.