Human Growth Hormones Notes http://www.health.harvard.edu/newsletters/Harvard_Mens_Health_Watch/2010/May/growth-hormone-athletic-performance-and-aging In 1513, the Spanish explorer Juan Ponce de Le�n arrived in Florida to search for the fountain of youth. If he got any benefit from his quest, it was due to the exercise involved in the search.
Few men today believe in miraculous waters, but many, it seems, believe in the syringe of youth. Instead of drinking rejuvenating waters, they inject human growth hormone to slow the tick of the clock. Some are motivated by the claims of the "anti-aging" movement, others by the examples of young athletes seeking a competitive edge. Like Ponce de Le�n, the athletes still get the benefit of exercise, while older men may use growth hormone shots as a substitute for working out. But will growth hormone boost performance or slow aging? And is it safe?
Human growth hormone: Up close and personal
Growth hormone (GH) is a small protein that is made by the pituitary gland and secreted into the bloodstream. GH production is controlled by a complex set of hormones produced in the hypothalamus of the brain and in the intestinal tract and pancreas.
The pituitary puts out GH in bursts; levels rise following exercise, trauma, and sleep. Under normal conditions, more GH is produced at night than during the day. This physiology is complex, but at a minimum, it tells us that sporadic blood tests to measure GH levels are meaningless since high and low levels alternate throughout the day. But scientists who carefully measure overall GH production report that it rises during childhood, peaks during puberty, and declines from middle age onward.
GH acts on many tissues throughout the body. In children and adolescents, it stimulates the growth of bone and cartilage. In people of all ages, GH boosts protein production, promotes the utilization of fat, interferes with the action of insulin, and raises blood sugar levels. GH also raises levels of insulin-like growth factor-1 (IGF-1).
Therapeutic use
GH is available as a prescription drug that is administered by injection. GH is indicated for children with GH deficiency and others with very short stature. It is also approved to treat adult GH deficiency — an uncommon condition that almost always develops in conjunction with major problems afflicting the hypothalamus, pituitary gland, or both. The diagnosis of adult GH deficiency depends on special tests that stimulate GH production; simple blood tests are useless at best, misleading at worst.
Adults with bona fide GH deficiencies benefit from GH injections. They enjoy protection from fractures, increased muscle mass, improved exercise capacity and energy, and a reduced risk of future heart disease. But there is a price to pay. Up to 30% of patients experience side effects that include fluid retention, joint and muscle pain, carpal tunnel syndrome (pressure on the nerve in the wrist causing hand pain and numbness), and high blood sugar levels.
GH doping
Adults who are GH deficient get larger muscles, more energy, and improved exercise capacity from replacement therapy. Athletes work hard to build their muscles and enhance performance. Some also turn to GH.
It's not an isolated problem. Despite being banned by the International Olympic Committee, Major League Baseball, the National Football League, and the World Anti-Doping Agency, GH abuse has tainted many sports, including baseball, cycling, and track and field. Competitive athletes who abuse GH risk disqualification and disgrace. What do they gain in return? And do they also risk their health?
Because GH use is banned and athletic performance depends on so many physical, psychological, and