That still means some 5 million Americans suffer symptomatic low testosterone - androgen deficiency - suggests a study by Andre B. Araujo,
Ph.D., and colleagues at New England Research Institutes Inc. By the year 2025, they calculate, there will be 6.5 million U.S. cases of androgen
"The positive message here is that not all men with low testosterone have symptoms," Araujo tells WebMD. "There are fewer men with symptomatic androgen deficiency than there are men with low testosterone."
Only half of men with low testosterone - low T, as it's coming to be called - have symptoms of androgen deficiency. The surprising finding comes from a study of about 1,500 randomly selected Boston-area men, evenly divided by age and race/ethnicity.
It's known that a man's testosterone levels decline over age. But there's no precipitous drop in a man's sex hormones as there is for a women at the time of menopause, Araujo and colleagues find.
"From age 30 on there is a gradual decline, 1 percent a year or more, in a man's testosterone production," Araujo says. "It is very gradual. There is no data to suggest anything like a male menopause."
Some men with low testosterone production develop symptoms of androgen deficiency. These symptoms include:
- Loss of sex drive
- Erectile dysfunction
- Bone loss or fracture
- Two or more of what endocrinologists call "nonspecific" symptoms:
sleep disturbance, depressed mood, lethargy, and diminished physical
Araujo finds that symptomatic androgen deficiency occurs in 3 percent to 7 percent of men under age 70 and in 18.4 percent of men over age 70.
Araujo and colleagues report their findings in the early online edition of the Journal of Clinical Endocrinology & Metabolism.
Testosterone Replacement Therapy: When?
So when does a man need testosterone replacement therapy? Clearly, men with symptomatic androgen deficiency would benefit from treatment if they have no contraindication such as prostate or breast cancer. But treatment guidelines from the Endocrine Society say symptom-free, age-related declines in testosterone should not be treated.
Robert Davis, M.D., professor of urology at the University of Rochester, N.Y., says men with a waistline over 40, high-blood pressure, and signs of insulin resistance - the so-called metabolic syndrome - are at high risk of androgen deficiency.
"These men have an incredibly high rate of androgen deficiency and treating them with testosterone may correct their metabolic syndrome because they may be able to burn energy better with more muscle," Davis tells WebMD. "Testosterone replacement may allow these men to avoid some of the consequences of metabolic syndrome such as coronary artery disease."
Davis says that androgen deficiency is an underdiagnosed and undertreated problem.
"One of the myths is that testosterone supplements will cause a cancer," he says. "We as urologists have been unduly reticent to use the drug. We know that prostate cancer often regresses when testosterone is removed, but there is very little evidence that supplementing normal testosterone levels increases risk of cancer - and there is some evidence it may lower it."
But what, asks Araujo, are the risks for men who have low testosterone levels but no symptoms?
Endocrinologist Sol Jacobs, M.D., assistant professor of medicine at Emory University in Atlanta, says doctors should try to figure out why a patient has low testosterone. But if there is no anatomical abnormality or disease causing his androgen deficiency, treatment may be a very good idea.
"Low testosterone levels will lead to bone density loss in men," Jacobs warns. "Even if you have a man who says, 'I feel great and don't want testosterone treatment,' at least measure his bone density. But usually the scenario is the patient is symptomatic and wants treatment."
Jacobs notes that the question of when to offer a patient testosteron replacement is highly controversial. Even the Endocrine Society's expert panel disagreed over the exact testosterone levels at which doctors should offer testosterone replacement therapy.
"At some point we need to know what a normal testosterone level is for
an aging man," Jacobs says.
By Daniel DeNoon
Reviewed by Louise Chang
B)2005-2006 WebMD, Inc. All rights reserved