Men taking testosterone replacement therapy (TRT) to stay virile as they age are 21 per cent more likely to have a heart attack or stroke, according to a study.

Researchers who analysed more than 15,400 men in the UK found TRT could lead to life-threatening heart problems in the first two years of use.

It adds to previous research that has suggested the risks of TRT may outweigh the benefits.

Testosterone replacement therapy (TRT) is prescribed to men with abnormally low testosterone which may have damaging effects on their energy levels, mood and sex drive.

Men taking testosterone replacement therapy to stay virile as they age are 21 per cent more likely to have a heart attack or stroke, according to a study (stock image)

The McGill University in Montreal analysed a large database of electronic medical records of patients enrolled in GP practices in the UK.

Participants were aged 45 years or older, with low testosterone levels – which may be diagnosed medically as hypogonadism.

Users of TRT had a 21 per cent greater risk of cardiovascular events compared with non-users, particularly ischaemic stroke, transient ischaemic attack (TIA), or myocardial infarction.

This meant that in the study group there were 128 extra heart attacks or strokes among the TRT group compared to the other men.

In their paper the researchers suggested a reason for this could be that extra testosterone gained from outside the body increases the likelihood of blood clots forming by causing platelets to clump together.

WHAT IS TRT? Testosterone replacement therapy (TRT) may be prescribed if a man is diagnosed with an abnormally low testosterone. Testosterone levels decline naturally in men as they age, but certain conditions can lead to an abnormally low level. TRT is traditionally used to treat hypogonadism, which occurs when your testes don’t produce enough testosterone. TRT is not normally recommended if a person has low levels of testosterone, but does not show symptoms, which may include erectile dysfunction, depression and loss of hair. When taking TRT, men notice a difference in their energy, sex drive, and muscle mass. Evidence shows TRT has side effects which may include: Acne and oily skin

Lower sperm count, which can cause infertility

Increased risk of blood clots

Shrinkage of the testicles

Larger breasts and ankles

Increased risk of heart attack and stroke The US Food and Drug Administration and Health Canada have issued warnings as to the potential risks associated with TRT, while the European Medicines Agency has found no consistent evidence for such risks. A loophole in FDA regulations allows pharmaceutical marketers to urge men to talk to their doctors if they have certain 'possible signs' they need treatment. Testosterone replacement therapy is available in several forms - a skin patch, gel, injection or mouth patch. Advertisement

The increased risk appeared to last only for a short time and to drop again after two years of TRT use.

But the research was cause for concern because, while the rates of hypogonadism have remained stable, TRT prescriptions have increased by almost 90 per cent from 2001 to 2010 in Britain, and over threefold from 2001 to 2011 in the US.

The study specifically looked at men with low testosterone levels due to ageing and not due to other causes, such as liver and kidney disease or an autoimmune disease.

The findings, published in The American Journal of Medicine, confirm concerns voiced by many health agencies about the potential risks associated with the treatment.

A small number of men experience immediate side effects of testosterone supplementation, such as acne, sleep apnoea, and swelling in the breasts or ankles.

Doctors have concern that TRT could stimulate the growth of prostate cancer cells, as well as blood clotting.

According to researchers, the evidence is limited on the long-term clinical benefits of TRT in ageing but healthy men.

Dr Christel Renoux, who led the research, said: 'We strongly recommend that clinicians proceed with caution when considering prescribing TRT and first discuss both the potential benefits and risks with patients.'

Dr Renoux's own research adds to previous findings that suggest TRT heightens cardiac risks, including death from heart disease.

For example, in 2010, researchers halted a study when early results showed that men using TRT treatments had noticeably more heart problems compared to men using a placebo.

The TOM (Testosterone in Older Men) Trial, reported in the New England Journal of Medicine, was supported by a grant from the National Institutes of Health.

Dr Renoux and colleagues said TRT may be increasingly prescribed to relieve nonspecific symptoms of ageing.