It could be said that testosterone is what makes men, men. It gives them their characteristic deep voices, big muscles, and body and facial hair, differentiating them from girls. It stimulates the development of the genitals , plays a role in sperm production, fuels libido, and contributes to normal erections. It also fosters the production of red blood cells, boosts mood, and aids cognition.
Over time, the testicular"machinery" that makes testosterone gradually becomes less effective, and testosterone levels start to drop, by about 1 percent a year, starting in the 40s. As guys get in their 50s, 60s, and beyond, they might begin to have symptoms and signs of low testosterone like reduced libido and sense of energy, erectile dysfunction, decreased energy, reduced muscle mass and bone density, and anemia. Taken together, these signs and symptoms are often called hypogonadism ("hypo" meaning low functioning and"gonadism" referring to the testicles). Yet it's an underdiagnosed issue, with just about 5 percent of those affected receiving treatment.
But little consensus exists about what constitutes low testosterone, when testosterone supplementation makes sense, or what risks patients face. Much of the current debate focuses on the long-held belief that testosterone can 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 reproductive and sexual problems. He's developed particular expertise in treating low testosterone levels. In this interview, Dr. Morgentaler shares his perspectives on current controversies, the treatment plans he uses with his own patients, and he thinks experts should reconsider the potential connection between testosterone-replacement therapy and prostate cancer.Symptoms and diagnosis
What signs and symptoms of low testosterone prompt the typical man to see a physician?
As a urologist, I have a tendency to see guys because they have sexual complaints. The primary hallmark of reduced testosterone is low sexual desire or libido, but another may be erectile dysfunction, and some other man who complains of erectile dysfunction should get his testosterone level checked. Men can experience other symptoms, like more difficulty achieving an orgasm, less-intense climaxes, a much lesser amount of fluid from ejaculation, and a sense of numbness in the manhood when they see or experience something which would usually be arousing.
The more of these symptoms there are, the more probable it is that a man has low testosterone. Many physicians tend to dismiss those"soft symptoms" as a normal part of aging, but they are often treatable and reversible by decreasing testosterone levels.
Aren't those the very same symptoms that men have when they're treated for benign prostatic hyperplasia, or BPH?
Not exactly. There are a number of drugs that may lessen sex drive, such as the BPH medication finasteride (Proscar) and dutasteride (Avodart). Those drugs can also reduce the amount of the ejaculatory fluid, no wonder. But a decrease in orgasm intensity usually does not go along with therapy for BPH. Erectile dysfunction does not ordinarily go together with it either, though certainly if a person has less sex drive or less attention, it is more of a struggle to get a good erection.
How can you determine if a man is a candidate for testosterone-replacement therapy?
There are two ways that we determine whether somebody has low testosterone. One is a blood test and the other one is by characteristic symptoms and signs, and the correlation between these two methods is far from ideal. Normally men with the lowest testosterone have the most symptoms and guys with highest testosterone possess the least. But there are a number of guys who have reduced levels of testosterone in their blood and have no symptoms.
Looking at the biochemical numbers, The Endocrine Society* believes low testosterone to be a total testosterone level of less than 300 ng/dl, and I believe that's a reasonable guide. However, no one really agrees on a number. It's not like diabetes, where if your fasting sugar is above a certain level, they'll say,"Okay, you've got it." With testosterone, that break point isn't quite as clear.
|*Notice: The Endocrine Society recommends clinical practice guidelines see here now with recommendations for who should and should see this site not receive testosterone Discover More treatment.
Is complete testosterone the right point to be measuring? Or should we be measuring something else?
Well, this is just another area of confusion and great debate, but I don't think it's as confusing as it is apparently in the literature. When most physicians learned about testosterone in medical school, they learned about overall testosterone, or all the testosterone in the body. However, about half of their testosterone that is circulating in the blood isn't readily available to the cells. It is closely bound to a carrier molecule known as sex hormone--binding globulin, which we abbreviate as SHBG.
The available portion of overall testosterone is called free testosterone, and it is readily available to the cells. Though it's only a small portion of the overall, the free testosterone level is a fairly good indicator of reduced testosterone. It is not ideal, but the correlation is greater than with total testosterone.
Do time of day, diet, or other factors affect testosterone levels?
For years, the recommendation has been to get a testosterone value early in the morning because levels start to drop after 10 or even 11 a.m.. However, the information behind this recommendation were attracted to healthy young men. Two recent studies demonstrated little change in blood glucose levels in men 40 and mature within the course of the day. One reported no change in average testosterone until after 2 p.m. Between 2 and 6 p.m., it went down by 13%, a modest amount, and probably insufficient to affect identification. Most guidelines nevertheless say it is important to do the test in the morning, but for men 40 and over, it likely does not matter much, provided that they get their blood drawn before 5 or 6 p.m.
There are some rather interesting findings about dietary supplements. By way of example, it appears that those that have a diet low in protein have lower testosterone levels than males who consume more protein. But diet hasn't been studied thoroughly enough to create any clear recommendations.