About Human Growth Hormones

Human growth hormone is the hormone responsible for growth, but serves several functions in the body. Its possible uses to help reverse signs of aging, increase energy and facilitate weight loss continues to be explored, but disagreement exists about effectiveness and long-term safety.

Definition

• Growth hormone (GH), which is called somatotropin, is a hormone that is produced and secreted by cells in the pituitary gland. Its job is to promote the growth of hard and soft tissues, affect metabolism and regulate the amount of sugar in the blood. The levels of GH peak in the body around puberty and from there begin a slow decline as we age. Normal signs of aging---less muscle mass, increased fat, and loss of bone density---are all associated with less growth hormone.

Insulin-Like Growth Factor

• Growth hormone works two ways, directly and indirectly. It can bind directly to special receptors on target cells and cause the desired effect, or it can work indirectly by causing the liver to secrete another hormone called insulin-like growth factor (IGF-1). IGF-1 then has the direct impact on cells.

Mechanism

• The growth of cells, bones and muscles occurs as an indirect process. Growth hormone plays three different roles in metabolism. It increases the rate of protein synthesis, promotes the breakdown of fat, and accelerates the rate at which the liver releases glucose into the blood. When GH instructs the body to breakdown fats, they are used for energy, so when the same GH tells the liver to raise glucose (sugar) in the blood, the body does not immediately use the glucose for energy. The net result is an increase in blood sugar levels. If blood sugar is too low, more GH is secreted to raise the level and bring it back into balance. A high level of amino acids will trigger a rise in GH so that more proteins can be built from the amino acids. External factors can also impact the amount of GH in the system, including stress, exercise, nutrition and sleep.

Disease

• Disease can be caused when there is too much or too little GH in the body. An improper balance might be caused by dysfunction of the cells producing GH or it could also be a problem with the cells that GH tries to activate. Lack of growth hormone causes growth retardation, or dwarfism. Too much GH causes giantism, or acromegaly. Giantism is a disease that begins in childhood and is usually caused by a tumor of the cells that produce GH. If an excess of GH occurs in adulthood, it's called acromegaly. This disease is caused by a tumor in the pituitary gland and usually develops gradually, resulting in overgrowth of arms and legs, swelling of soft tissues and cardiac disease.

Uses

• Growth hormone is used clinically to treat diseases that result from a deficiency of hormone. It makes a big difference to children who are deficient because without growth hormone treatment they would not even reach a height of 5 feet. While its potential continues to be tested and improved, growth hormone shows promise as a treatment to slow the normal symptoms of aging. Interesting research also indicates that exercise helps to improve the natural secretion of growth hormone and that prevents loss of lean mass while facilitating loss of fat.