What are hormones?Hormones are chemical messengers produced by glands in the body and delivered via the bloodstream to act on other organs in the body.  Back to top
What is testosterone?Testosterone is the most important androgen or male hormone. It circulates in the blood to act on a number of bodily functions and plays a vital role in reproductive and sexual function. Testosterone is responsible for the general growth that happens in young boys at puberty including development of the genitals, beard and body hair, muscle gain and other characteristics of the adult male. The equivalent sex steroid produced by women is oestradiol. Back to top
Where is testosterone produced?Testosterone is mainly produced in the testes by cells (Leydig cells), which lie between the sperm-producing tubes (seminiferous tubules) that make the sperm. Testosterone is carried in the blood to a number of organs throughout the body including the skin, hair and muscle. Small amounts of testosterone are also made by the adrenal glands, which are walnut sized glands that sit on top of the kidneys.
‘Androgens’ is the collective term for all the male sex hormones, including testosterone, that play a key role in reproductive and sexual function. Testosterone is responsible for producing physical characteristics of male puberty such as penis development, and for those features typical of adult men such as facial and body hair. Testosterone also stimulates cells in the testes to produce sperm.
Testosterone is also very important for continuing good health in many non-reproductive tissues. It is important for:
- the growth of bones and muscles;
- stimulates the bone marrow to make red blood cells;
- mood, sex drive (libido) and certain aspects of mental ability.
In summary, testosterone is needed for the best possible health in men. Back to top
What is androgen deficiency?Androgen or testosterone deficiency is when the body is unable to produce enough testosterone for the body to function normally. Although not a life-threatening condition, it can have a major affect on quality of life.
Androgen deficiency may happen as a result of a testicular problem (hypogonadism) or a lack of hormonal drive from the brain to the testis. Back to top
What is testosterone therapy?Testosterone therapy is hormone replacement given via:
- injections;
- oral capsules;
- skin patches;
- creams or gels;
- implants.
It is prescribed for men with clinically proven lowered testosterone levels. Once started, this treatment is usually continued for life and needs to be checked regularly by medical professionals. Back to top
When should testosterone therapy be considered? Testosterone therapy can offer benefits to men with known causes of androgen deficiency. It has also been shown to help otherwise healthy men whose testosterone levels are always low for no clear reason.
However, because of the lack of data defining the point at which testosterone therapy should be considered in ageing men, all cases of suspected androgen deficiency with an unknown cause should be treated on an individual basis. At least two blood tests should be taken and detailed discussion with a qualified doctor should take place before starting this treatment. Back to top
How many men are affected?Androgen deficiency affects about one in 200 men under 60 years of age. It is usually the result of genetic disorders, damage to the testes, or rarely, a lack of hormones produced by the brain.
It is uncertain how many men over 60 years of age are androgen deficient with some estimates suggesting that one in 10 older men may have low testosterone levels. The ageing process, medical illnesses and obesity all affect testosterone levels.
It is likely that androgen deficiency is under-diagnosed in the community and that many men are missing out on the benefits of treatment. Back to top
How does ageing affect testosterone levels?Testosterone levels in men are highest between the ages of 20 to 30 years. As men age there is a modest, gradual drop in testosterone - levels fall by about a third between the ages of 30 to 80 years. Some men will experience a greater drop in testosterone levels. Unlike women, whose oestrogen levels fall rapidly when they go through menopause, men’s testosterone levels fall much more gradually and over a longer period of time.
The causes and extent of this problem in ageing men are unknown. Medical experts are still trying to decide at what point testosterone levels in the blood are low enough for testosterone therapy to be helpful in ageing men. Back to top
Does 'male menopause' exist?Terms such as ‘male menopause’ or ‘andropause’ are not accurate. Menopause is the stopping of menstrual cycles (periods) that only happen in women. Testosterone levels in men do not stop suddenly but slowly drop with age. Therefore, the hormone changes with ageing in men and women are diagnosed and treated differently. Back to top
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