In many people, adult growth hormone (hGH or GH) deficiency is the continuation of a disorder that began early in life, in infancy or childhood. This type of adult GH deficiency is referred to as having childhood onset.

For some cases, the causes of GH deficiency in childhood cannot be determined; this type of disorder is referred to as idiopathic. Some known causes may include:

Developmental defects in or near the pituitary gland

Genetic problems with the production of GH

Damage to the pituitary gland or the surrounding area due to tumors, infection, radiation treatment, or severe head injury

Some children with GH deficiency may gain the ability to secrete GH with time and may not require GH therapy as adults. However, scientific evidence suggests that many adults who were GH-deficient as children and continue to be GH-deficient as adults may need to continue therapy into adulthood in order to have enough GH to meet metabolic demands as adults (although many factors can contribute to such conditions).