''The goal of testosterone treatment is to keep the levels within normal range," says Farid Saad, director of scientific affairs for Bayer Schering Pharma in Berlin. Saad presented two of the studies at the meeting, held in San Francisco. Bayer Schering Pharma makes several testosterone products.
Low levels of testosterone are common with age, Saad says, occurring in about 18% of 70-year-olds. Low levels of testosterone, he says, are associated with the metabolic syndrome -- a cluster of risk factors such as abnormal cholesterol and high blood pressure that boost risk of heart disease, stroke, and type 2 diabetes as well as other risks to health.
In the studies, Saad and his colleagues found that testosterone replacement therapy reduced the metabolic syndrome risk factors and did so in a similar way in all the age ranges studied.
Testosterone Replacement Therapy and Heart Disease Risks
In the first study, Saad's team looked at 95 men, aged 34 to 69, with low levels of testosterone.
All had metabolic syndrome. Those who have this diagnosis must have three of five risk factors: increased waist circumference, low "good" cholesterol or HDL, high triglycerides , elevated blood pressure, and elevated blood sugar.
"We treated them for at least a year," he tells WebMD. Every three months, they measured cholesterol, waist circumference, and other parameters.
The testosterone replacement was given as a long-acting injection, every three months. The same product is not yet available in the U.S., Saad says, although other types are.
Testosterone Replacement Therapy: Test Results
"We saw a consistent improvement of the parameters of metabolic syndrome," Saad says. The men were not given a special diet or exercise program .
The supplemental testosterone reduced total cholesterol, "bad" LDL cholesterol , triglycerides, and body mass index while improving "good" HDL cholesterol . The men lost their pot bellies, Saad says. "What we see after 12 months is a reduction in two or three trouser sizes, three or four inches off the waist. We see a reduction by one-fourth to one-third of their total cholesterol."
No adverse effects were reported, he says.
While hormone replacement therapy for women has been found to be associated with increased risks of heart disease and other problems, Saad doesn't foresee that will be the case with testosterone replacement. "There are fundamental differences between hormone replacement in women and testosterone treatment in men," he tells WebMD.
Testosterone Replacement Therapy: No Age Effects?
In a second study, Saad divided the same 95 men into three groups, based on age: less than 57, 57 to 63, and older than 63.
They found the older men and the younger men had similar improvement in their risk factors.
Testosterone Replacement Therapy: Follow-up
"There are some precautions with testosterone supplementation," Saad tells WebMD. "We need to monitor the prostate."
"It is well known that with prostate cancer , the cancer is usually dependent on testosterone. Prostate cancer is a slow-growing tumor." Cancer of the gland must be ruled out before starting supplements, he says. He also advises routine prostate checkups while on treatment.
A test to monitor red blood cell formation, called a hematocrit, is needed, too. "Testosterone increases red blood cells," he says. In excess, it can theoretically boost heart attack or stroke risk.
Testosterone and Death Risk
Low testosterone levels are associated with an increased risk of eath, according to Robin Haring, a researcher from the Institute for Community Medicine at Ernst-Moritz-Arndt University in Griefswald, Germany, who presented the finding at the meeting.
He evaluated data on nearly 2,000 men, aged 20 to 79, who participated in the Study of Health in Pomerania, following them for seven years until August 2007. He noted testosterone levels, age, weight , smoking habits, and physical activity. The drugmaker Novo Nordisk partly funded the study.
During the follow-up, 226 men died. "Men with low testosterone have a more than twofold higher risk of death during the follow-up period," he says.
They were more likely to die of cardiovascular disease and cancer, but not of other causes.
Testosterone Replacement Therapy: Long-Term Effects Unknown
Another researcher, Jane F. Reckelhoff, PhD, professor of physiology and biophysics at the University of Mississippi Medical Center in Jackson, offers a caveat about supplemental testosterone: "We don't know what the long-terms effects are. The safety studies have not been done and they need to be done."
She reviewed the studies for WebMD and has published on a review about testosterone supplements for the American Journal of Physiology Renal Physiology.
Her chief concerns: "Testosterone [in excess] can increase blood pressure and compromise kidney function."
But an advocate of testosterone replacement therapy, Martin Miner, MD, co-director of the Men's Health Center at the Miriam Hospital of Brown University in Providence, R.I., says the studies show that restoring testosterone when it is low improves metabolic syndrome factors and could help prevent type 2 diabetes and cardiovascular risks.
He agrees close monitoring of men on testosterone is needed. "Checking hematocrit, PSA (prostate-specific antigen), and lower urinary tract symptoms in men is vital to the management of testosterone replacement therapy," he says.
By Kathleen Doheny
Reviewed by Louise Chang
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