By Caroline Ryan BBC News Online health staff

Testosterone helps heart failure, seen in right-hand image

Patients with the condition were assessed before and after being given the hormone to see if it improved their ability to exercise.

The Sheffield-based researchers found the hormone significantly improved the pumping ability of the heart.

Men with low hormone levels benefited most from the treatment.

Damage

Although men do not go through a physical menopause as women do, they do experience a fall in testosterone levels in middle age, say researchers.

Postmenopausal women have a higher risk of developing coronary heart disease than premenopausal women, suggesting female hormones protect against the condition.

We are proposing to give men a replacement dose, bringing the hormone up to the body's natural level Dr Kevin Channer, Royal Hallamshire Hospital

Studies have indicated that around 25% of men with coronary artery disease have low testosterone levels.

Researchers speculated that men could be affected by a lack of their natural hormones in the same way that women are.

Heart failure occurs when the heart muscle is damaged and becomes less efficient at pumping blood around the body, causing fatigue and tiredness.

One way to treat the condition is by relaxing the blood vessels. Testosterone has been shown to have this vasodilatory effect.

Prostate risk

To test the theory, researchers from the Royal Hallamshire Hospital gave 12 men with heart failure testosterone. The men were given low doses which would not mean they had out-of-the-ordinary levels of the hormone.

On separate days, they were given a dummy pill. Neither the men nor the researchers knew on which day they were given the testosterone treatment.

It was found that when they were given testosterone the men's cardiac output - the heart's ability to pump blood - improved significantly.

A second study by the team looked at the effect of testosterone on 20 men, which showed an improvement in walking distance

Previous research by the team had shown testosterone could also help men with angina.

However, the researchers, led by Dr Kevin Channer a consultant cardiologist at the Royal Hallamshire, say more research needs to be carried out into testosterone therapy, not least because there are fears giving men the hormone could increase their risk of prostate cancer.

The researchers are now looking at whether testosterone therapy can have longer term benefits.

Sixty men are involved in a longer term study which will finish in February next year.

Half are taking testosterone therapy, and the rest a dummy version, but who was given what will not be revealed until the end of the study.

'Prolonging life'

Dr Channer told BBC News Online: "We know testosterone will make men feel better and reduce their symptoms both in heart failure and angina.

"What we don't know yet is if it will prolong life or reduce cardiovascular events such as stroke or heart attacks."

He said: "We are proposing to give men a replacement dose, bringing the hormone up to the body's natural level.

"Even if you can't prolong life by giving men testosterone, if you could make men feel better with a hormone which is naturally occurring, that has to be a good thing."

Dr Channer added: "I do believe this is an important thing. But I wouldn't advise at the moment it's long-term use in men who didn't have low levels of testosterone."

The team's research has received funding from the National Heart Research Fund, the British Heart Foundation, industry and charities.

Alison Shaw, cardiac nurse at the British Heart Foundation, said: "From limited studies testosterone appears to help arteries dilate increasing the amount of blood and oxygen getting around the body.

"However, at present there is no positive link between testosterone and an increased risk from coronary heart disease.