Concerns raised over male HRT

Men were studied while they slept

Hormone therapy for men could cause sleep problems thought to increase the risk of developing heart disease, scientists say.

Researchers gave high doses of testosterone therapy to healthy men aged over 60.

It was found the treatment increased episodes of sleep apnoea - a condition where breathing is obstructed during sleep.

But advocates of male HRT say the problem may be due to high doses used.

In the US, where testosterone is marketed directly to men, the amount prescribed has tripled over the last decade.

We know high levels of the hormone are not necessarily good for you Dr Kevin Channer, Royal Hallamshire Hospital

The hormone is less widely used in Europe or Australasia.

Some researchers have suggested testosterone could be used to treat heart disease, but there are concerns it could increase a man's risk of prostate cancer.

Experts are also divided over whether middle-aged men should be given the hormone to treat the so-called male menopause, which some say is due to inactivity, depression and middle-aged spread rather than a fall in testosterone levels.

Injections

In this study, researchers from the Anzac Research Institute in Sydney gave the hormone or a dummy version to 17 men via three weekly injections.

The dose used was two to three times the amount commonly used to treat older men with low testosterone levels.

Eight weeks later, the men who had received the placebo were given testosterone and vice versa.

Neither the men nor the researchers knew which they were getting.

At the end of the study, it was found that when men were given testosterone they experienced 50% more episodes of sleep apnoea during each hour they were asleep.

The researchers suggest hormone replacement therapy could cause men with mild apnoea to develop a more severe form of the condition - which would also triple their risk of having high blood pressure, heart attacks or strokes.

However, it is not clear why testosterone causes sleep apnoea.

Dr Brendon Yee, who carried out the research, told New Scientist magazine: "Testosterone could change the diameter of the upper airway or its collapsibility by affecting the neuromuscular mechanism."

Dr Kevin Channer of the Royal Hallamshire Hospital in Sheffield is carrying out research which suggests therapeutic doses of testosterone - bringing levels up to normal - can help men with heart disease.

He told BBC News Online: "The Australian researchers used very high doses of testosterone, two to three times that which we would use.

"We know high levels of the hormone are not necessarily good for you because of evidence of the effects of anabolic steroids."