Growth Hormone Overview

Growth hormone (somatotropin) is an organic compound that stimulates the growth of bone, cartilage, and tissue. It also influences the metabolism of protein, carbohydrate, and fat. Growth hormone is one of several hormones produced by the anterior (front) lobe of the pituitary gland, which is located at the base of the brain.

Sometimes the pituitary gland malfunctions and produces too little or too much growth hormone. The malfunction may be caused by:

• Genetic (inherited) mutations.
• A damaged pituitary gland due to radiation, trauma, a tumor, or surgery. (In adults, the damage to the pituitary gland is typically caused by a tumor.)
• Problems with the hypothalamus, which is a region of the brain that controls the pituitary gland.

Children need growth hormone to grow normally. Although an adult's bones have stopped growing lengthwise, adults continue to need growth hormone to maintain their bones, muscles, and body fat, as well as maintain their strength, energy, and quality of life. Bones grow lengthwise from the growth plate (epiphyseal plate), which is the cartilage located between the shaft and the end of a bone. The amount of growth hormone produced by the pituitary gland determines how slowly or fast bones grow.

Growth hormone production normally slows down during adolescence. At the end of adolescence a person's bones normally fuse and stop growing lengthwise. As a result, the symptoms depend on whether a person is under- or overproducing growth hormone and whether this problem occurs before or after the bones fuse.

Growth hormone deficiency symptoms include:

• Short stature in childhood.
• Decreased muscle mass and weakness in adulthood.

Growth hormone excess symptoms include:

• Tall stature in childhood.
• Enlarged features and thickened skin in adulthood.