It could be said that testosterone is what makes guys, guys. It gives them their characteristic deep voices, big muscles, and body and facial hair, differentiating them from girls. It stimulates the growth of the genitals at puberty, plays a role in sperm production, fuels libido, and leads to regular erections. It also boosts the production of red blood cells, boosts mood, and assists cognition.
As time passes, the testicular"machinery" that makes testosterone slowly becomes less powerful, and testosterone levels begin to drop, by approximately 1 percent per year, starting in the 40s. As men get into their 50s, 60s, and beyond, they might start to have signs and symptoms of low testosterone like lower sex drive and sense of energy, erectile dysfunction, diminished energy, reduced muscle mass and bone density, and nausea. Taken together, these signs and symptoms are often referred to as hypogonadism ("hypo" meaning low working and"gonadism" referring to the testicles). Researchers estimate that the condition affects anywhere from two to six million men in the USA. Yet it's an underdiagnosed issue, with just about 5% of those affected undergoing therapy.
Much of the current debate focuses on the long-held belief that testosterone may stimulate prostate cancer.
Dr. Abraham Morgentaler, an associate professor of surgery at Harvard Medical School and the director of Men's Health Boston, specializes in treating prostate ailments and male sexual and reproductive problems. He's developed particular experience in treating lower testosterone levels. In this interview, Dr. Morgentaler shares his views on current controversies, the treatment plans he uses with his patients, and he thinks experts should reconsider the potential connection between testosterone-replacement therapy and prostate cancer.Symptoms and diagnosis
What symptoms and signs of low testosterone prompt the typical man to see a physician?
As a urologist, I tend to observe men since they have sexual complaints. The primary hallmark of reduced testosterone is reduced sexual desire or libido, but another can be erectile dysfunction, and any man who complains of erectile dysfunction must possess his testosterone level checked. Men may experience other symptoms, like more difficulty achieving an orgasm, less-intense climaxes, a much smaller quantity of fluid out of ejaculation, and a feeling of numbness in the penis when they see or experience something which would normally be arousing.
The more of these symptoms you will find, the more probable it is that a man has low testosterone. Many physicians tend to discount those"soft symptoms" as a normal part of aging, but they are often treatable and reversible by normalizing testosterone levels.
Are not those the very same symptoms that men have when they're treated for benign prostatic hyperplasia, or BPH?
Not precisely. There are quite a few drugs which may reduce libido, such as the BPH medication finasteride (Proscar) and dutasteride (Avodart). Those drugs can also reduce the quantity of the ejaculatory fluid, no question. But a decrease in orgasm intensity usually does not go together with therapy for BPH. Erectile dysfunction does not usually go along with it either, though surely if a person has less sex drive or less interest, it's more of a struggle to have a fantastic erection.
How do you determine if or not a person is a candidate for testosterone-replacement therapy?
There are two ways that we determine whether someone has reduced testosterone. One is a blood test and the other one is by characteristic symptoms and signs, and the correlation between those two approaches is far from ideal. Generally men with the lowest testosterone have the most symptoms and guys with highest testosterone possess the least. However, there are some men who have low levels of testosterone in their blood and have no symptoms.
Looking purely at the biochemical numbers, The Endocrine Society* believes low testosterone to be a total testosterone level of less than 300 ng/dl, and I think that's a reasonable guide. But no one quite agrees on a number. It's not like diabetes, in which if your fasting sugar is above a certain level, they will say,"Okay, you've got it." With testosterone, that break point isn't quite as clear.
|*Note: The Endocrine Society publishes clinical practice guidelines with recommendations this link for who should and should not receive testosterone useful source treatment.
Is total testosterone the right thing to be measuring? Or should we be measuring something different?
Well, this is another area of confusion and good discussion, but I do not think it's as confusing as it appears to be in the literature. When most doctors learned about testosterone in medical school, they heard about overall testosterone, or all of the testosterone in the human body. However, about half of their testosterone that is circulating in the blood is not available to the cells. It's tightly bound to a carrier molecule known as sex hormone--binding globulin, which we abbreviate as SHBG.
The available part of overall testosterone is known as free testosterone, and it's readily available to the cells. Though it's just a little fraction of the total, the free testosterone level is a fairly good indicator of reduced testosterone. It's not perfect, but the correlation is greater compared to testosterone.