During puberty, rising levels of testosterone encourage the growth of the testicles, penis, and pubic hair. The voice begins to deepen, and muscles and body hair grow. Along with these changes comes growing sexual desire. A man with low levels of testosterone may lose his desire for sex.
Sexual stimulation and sexual activity cause testosterone levels to rise. Testosterone levels can drop during a long period of sexual inactivity. Low testosterone can also result in erectile dysfunction ED. The body has a system for controlling testosterone, sending messages through hormones and chemicals that are released into the bloodstream.
In the brain, the hypothalamus tells the pituitary gland how much testosterone is needed, and the pituitary relays that information to the testicles. Testosterone plays a role in certain behaviors, including aggression and dominance. It also helps to spark competitiveness and boost self-esteem. Low testosterone may result in a loss of confidence and lack of motivation. Low testosterone can cause sleep disturbances and lack of energy. Other biological and environmental factors are also involved.
As a man transitions from childhood to adulthood, testosterone spurs the growth of hair on the face, in the armpits, and around the genitals. Hair also may grow on the arms, legs, and chest. A man with shrinking levels of testosterone actually may lose some body hair. Testosterone replacement therapy comes with a few potential side effects, including acne and breast enlargement.
Testosterone patches may cause minor skin irritation. Topical gels may be easier to use, but great care must be taken to avoid transferring testosterone to someone else though skin-to-skin contact. Testosterone is one of many factors involved in the development of muscle bulk and strength.
Testosterone increases neurotransmitters, which encourage tissue growth. It also interacts with nuclear receptors in DNA, which causes protein synthesis. Testosterone increases levels of growth hormone. That makes exercise more likely to build muscle. Testosterone increases bone density and tells the bone marrow to manufacture red blood cells. Men with very low levels of testosterone are more likely to suffer from bone fractures and breaks.
Testosterone also plays a role in fat metabolism, helping men to burn fat more efficiently. Dropping levels of testosterone can cause an increase in body fat. For human males with intact gonads, testosterone increases during puberty. It deepens the voice, increases muscle growth, promotes facial and body hair, and spurs the sex drive. Testosterone also is associated with personality traits related to power and dominance.
Testosterone levels fluctuate throughout the day, and are usually highest in the morning. They peak in the late teens to early twenties, after which they decline slowly, but steadily, as men age.
Although there is no standard definition of "low" testosterone, a healthy range spans between to 1, nanograms per deciliter of blood.
Questions inevitably arise: If even scientists don't agree on what, exactly, "low T" means, how can anyone diagnose it? At what point is it problematic? And, most importantly, how can you know whether you are a candidate for TRT? Kathleen L. Although her male patients may or may not get the low testosterone diagnosis they believe Dr. Wyne should give them, they will get a comprehensive examination.
Besides their testosterone level, she will look at their triglycerides, glucose blood sugar tolerance, liver enzymes, and other counts as well as the condition of their testicles.
Wyne told me that although she has seen an increase in male patients asking about low testosterone, she hasn't seen an actual increase in the condition itself. We know that even 15 pounds makes a huge difference to their level.
Most of these guys actually have 50 pounds to lose. In Seattle, Dr. Bradley D. Anawalt, an endocrinologist and professor of medicine at the University of Washington, said it's challenging for physicians to tease out the actual causes of a man's low energy, drop in sexual interest, and other potential symptoms of low testosterone that may as likely be caused by something else.
Anawalt, "is the man who is 50 pounds overweight and sedentary, who sees a TV ad and goes to see his doctor. Let's say he has a thoughtful doctor who does the right test, at the right time of day morning , and the test comes back low. Many of these guys will have low or slightly low testosterone. We have no evidence for whether or not it's a benefit to give these guys testosterone.
Anawalt called the diagnosis and treatment of low testosterone a careful balancing act. He explained that physicians need to be aware that men coming in with low libido, sexual function, osteoporosis, or new breast sensitivity might well have low testosterone. Besides measuring testosterone— usually two or even three times—confirmatory tests will also measure other hormones that regulate testosterone and sperm production in the testicle. Anawalt, "we will tell a man we don't think you're suffering from the effects of low testosterone.
Sometimes, low testosterone can actually be a good thing. In fact there are hundreds of thousands of men in North America at any given time whose T level is intentionally lowered using drugs derived from testosterone or estrogen.
These are men being treated for prostate cancer. Richard J. Wassersug, PhD, an adjunct professor of urology at the University of British Columbia, described his personal experience with androgen deprivation therapy ADT.
This produces a cognitive dissonance. Wassersug, whose background is in evolutionary biology, also noted that lower testosterone in older men may be adaptive, a positive benefit, as our bodies age and become increasingly frail. When Solvay Pharmaceuticals, maker of market-dominating Androgel, launched its "Low T" campaign, in , it claimed that 13 million American men over age 45 suffered from low testosterone, 90 percent of them undiagnosed.
Its website, IsItLowT. In its first year alone, 1. Today, numerous websites peddle the drug without requiring a prescription. As AdWeek pointed out when the campaign launched, "One of the advantages of taking the unbranded route for Androgel is that the company does not have to warn consumers quite so prominently about Androgel's side effects. Adriane Fugh-Berman, associate professor of pharmacology and director of the industry watchdog group PharmedOut.
In Australia, where it is illegal for drug makers to advertise directly to consumers—as it is everywhere except the United States and New Zealand— Dr. Sperm production is actually stimulated by hormones other than testosterone. Testosterone is required for sperm production, but the level in the testes where sperm are produced is many times higher than in the blood. Even men with low or borderline T levels may have sufficient T levels for sperm production. One side effect of testosterone treatment is infertility.
Testosterone treatment decreases sperm production by decreasing levels of another hormone, follicelstimulating hormone FSH , which is important for stimulating sperm production. In most cases, the infertility caused by testosterone treatment is reversible. Men who have received testosterone for a shorter period of time probably recover more quickly. For a small percentage of men, the infertility is not reversible.
It is generally believed that testosterone given by shots and pellets are more likely to cause infertility than gels, although any form of testosterone supplementation can disrupt the normal hormonal balance required for sperm production.
He should consult with a male reproductive specialist. Men should avoid testosterone treatment until they are done trying to have their own biological children. If a man has a pituitary disorder that is causing the low testosterone, then he can be treated with a pituitary hormone hCG that will increase his T level without disrupting sperm production.
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