01 November 2010

Testosterone not always the culprit

A new study has added to evidence that men's levels of testosterone can vary quite a bit without causing sexual problems such as impotence and decreased libido.


A new study adds to evidence that men's levels of the hormone testosterone can vary quite a bit without causing sexual problems like impotence and decreased libido.

"Testosterone replacement therapy has become a very common thing," said Dr Michael Marberger, who heads the urology department at the University of Vienna Medical School in Austria, and led the new study."It is like putting more gas in the car to make it go faster," he said.

Low sex drive

There is no doubt that very low testosterone levels affect the body and dampen sex drive. But where to set the threshold is still an open question, whose resolution is not made easier by natural variation in the male sex hormone.

Its level dwindles with age, for instance, and fluctuates between countries, races and individuals - even from one hour to the next.

In the new study, funded by GlaxoSmithKline, researchers used data from an earlier study of more than 8,000 middle-aged and older men at risk for developing prostate cancer.

The men filled out questionnaires about their sexual function - whether they could keep an erection, whether they lacked sex drive - and had blood drawn. Various other measures were taken, too.

Testosterone levels

One in five had testosterone levels below 300 nanograms per deciliter of blood, the threshold for what Solvay and others call "Low T."

And about two in five men had at least "a small problem" in one or more areas related to their sex life.

Of the measures taken - age, urinary symptoms, body mass index (BMI) and diabetes - testosterone showed the weakest link to the men's sexual function.

"We need a lot less testosterone for sexual function than people used to think," said Marberger, whose findings appear in the British Journal of Urology International. "Obesity impacts sexual function much more."

For instance, earlier research has shown that erectile dysfunction can disappear by itself over time, especially in men who aren't obese.

Docs too quick to give testosterone 

Marberger, a paid consultant for GlaxoSmithKline, which makes diabetes and weight loss drugs, added that doctors are often too quick to give patients testosterone, when high blood pressure or obesity might be the real culprit.

Every year, millions of testosterone prescriptions are written to men, and some products aren't cheap and can cause swelling around the joints and in the breasts - although Marberger said most side effects aren't serious.

Dr Frederick Wu, a hormone expert at the University of Manchester, was critical of the some of the study's methods, but agreed with the overall message.

Erectile dysfunction

"Most people with erectile problems do not have hormone problems," he said, but often have blockages in the arteries in their penis.

He stressed, however, that a lot of research has found that once testosterone dips below a certain threshold, it does impact sexual function.

But the exact level is controversial, and the picture gets extra murky because many of the symptoms that accompany very low testosterone - fatigue, depression, loss of muscle strength and bone density - are commonly found in seniors.

"Low testosterone and sexual problems quite often coexist," said Wu, "but the causal relationship isn't clear." (Reuters Health/ November 2010)

Read more:
Visit our Erectile Dysfunction Centre
Can young men get erectile dysfunction?
Does erectile dysfunction sometimes clear up by itself?


Complete our Health of the Nation Survey and stand a chance to win a scooter!




Read Health24’s Comments Policy

Comment on this story
Comments have been closed for this article.

Live healthier

Contraceptives and you »

Scientists create new contraceptive from seaweed Poor long-term birth control training leads to 'accidents'

7 birth control myths you should stop believing

Will the Pill make you gain weight? Can you fall pregnant while breastfeeding? We bust seven common myths about birth control.

Your digestive health »

Causes of digestive disorders 9 habits that could hurt your digestive system

Your tummy rumblings might help diagnose bowel disorder

With the assistance of an 'acoustic belt', doctors can now determine the cause of your tummy troubles.