All you need to know about TRT

testosterone replacement therapy

TRT is short for testosterone replacement therapy and refers to the clinical administration of testosterone when natural levels are low.

What is testosterone and what does it do?

Most people know that testosterone is a hormone produced by men but it is less commonly known that women need testosterone too, albeit at a much lower level. In men, testosterone plays an important role in sexual development and function and it is also required for building and maintaining muscle mass, bone density and cognitive function.

In women, oestrogen is the main sex hormone but testosterone is also important for normal sexual function.

How are testosterone levels regulated?

Our bodies are set up to maintain testosterone levels at an optimal level. If the hypothalamus or pituitary gland detects that levels have dropped below that which is desirable then they send out hormone signals to stimulate the production of more testosterone. Once the level is raised then this increase is detected and the hormone signal is switched off to prevent over-production.

Normally this tightly regulated mechanism keeps testosterone levels within a small window. However, sometimes the mechanism does not work as it should and testosterone levels drop below where they should be. This may be known as androgen insufficiency or testicular insufficiency. There are several types of low testosterone, depending on where the fault in the regulatory system lies.

Hypogonadotrophic hypogonadism is where the pituitary gland does not produce enough of its hormone in order to sufficiently stimulate testosterone production in the testes.

Hypergonadotropic hypogonadism is where the hormone signals are reaching the testes but they do not respond sufficiently to keep testosterone levels normal.

Idiopathic hypogonadism is where the hypothalamus does not produce enough of the hormones needed to stimulate the pituitary gland, or the pituitary gland does not respond correctly to the hormones that are produced.

Low testosterone levels

Testosterone levels can be affected by many factors including, but not limited to:

  • High levels of exercise, for example, overtraining at the gym or running a marathon
  • High blood glucose, which is why diabetics often have lower than normal testosterone levels
  • Age
  • Shift work or lack of sleep due to other reasons
  • Alcohol or recreational drug use
  • Physical damage to, or removal of, the testes

Men and women with sub-optimal testosterone levels are likely to experience an increase in body fat and a decrease in muscle mass. They may also lose height and confidence and suffer from various sleep problems. Low testosterone is linked to depression, anxiety and a lack of sexual drive.

Men with low testosterone levels may experience problems getting or maintaining an erection, together with body and facial hair loss and a loss of energy.

What is testosterone replacement therapy?

Testosterone replacement therapy is a form of hormone replacement therapy which is designed to return testosterone levels to normal. Testosterone has been used medically for over 75 years and has been rigorously tested and monitored to ensure that it is safe for patients.

There was a time when testosterone was taken orally but this was linked to liver toxicity so oral testosterone is rarely used these days. More commonly, testosterone is injected into the bloodstream where it is bio-identical to the testosterone which is naturally made in the body. Androgen receptors, which testosterone binds to, react in the same way to injected testosterone as they do to testosterone which is naturally produced.

Testosterone is also available in creams which are applied to the body. These contain the same testosterone that the body makes but it is combined with natural binders which cause it to be released slowly into the bloodstream, avoiding sudden peaks and troughs in levels.

What are the side effects of testosterone replacement therapy?

Historically there have been suggestions that testosterone replacement therapy could be linked to prostate cancer or an increased risk of heart disease. More recent reviews of the evidence, however, do not support these links. In fact, low testosterone levels have been shown to be associated with chronic diseases although it is not clear whether testosterone level has a causative effect.

Low testosterone levels can make men less susceptible to male pattern baldness, so when levels are raised back to normal, the risk of hair loss may increase to an extent. However, testosterone on its own does not cause hair loss.

Low levels of testosterone may be linked to a reduction in penis size and function, so one potential side effect of TRT is an increase in penis size and an improvement in function.

Image Credits: testosterone from bangoland /Shutterstock