Growth hormone deficiency can be both a total or a partial condition, resulting in impaired physical development.

The growth hormone is one of the hormones produced in the pituitary gland (hypophysis), a small gland situated on the underside of the brain. Secretion of the growth hormone is controlled by other hormones released by a different part of the brain. When the growth hormone enters the bloodstream it stimulates the liver to secrete yet another hormone, 'insulin-like growth factor' (primarily IGF-1).

The elderly naturally produce less growth hormone than young adults.

A total growth hormone deficiency is often discovered in a child's infancy. At birth, the infant's height and weight are normal. However, between three to nine months the child's growth rate will be reduced (growth disturbance). Later, the ability to gain weight begins to diminish; teeth development is delayed and the child may also acquire a thick layer of fat under the skin. This symptom will not always be visible if the growth hormone deficiency is only partial.