Growth hormone is a protein hormone made by the pituitary gland. It is widely known that growth hormone is needed for children to grow. However, after physical growth stops, the body still needs growth hormone for its cells to function properly. Adults who don’t produce enough growth hormone on their own are said to have adult growth hormone deficiency, or AGHD.

In adults, loss of GH doesn’t impact height as it does in children, but it does affect the body in many other ways. Growth hormone is necessary for normal brain function. Therefore, deficient adults may see psychological changes in addition to the major changes in body composition. Symptoms of adult deficiency of growth hormone include:

Loss of muscle
Decreased exercise capacity
Accumulation of fat (especially in the abdomen)
Decrease in bone density
Joint pain
Trouble sleeping
Fatigue / Loss of energy
Blood lipid changes (increase in "bad" LDL cholesterol, decrease in "good" HDL cholesterol)
Depression
Decrease in sexual function

GH deficiency in adults is typically caused by injury to the pituitary gland, resultant from trauma, inflammation, or the presence of a pituitary tumor, or pituitary irradiation.