Testosterone in Men

Contrary to popular belief, testosterone isn’t just a sex hormone. Testosterone is essential for sexual function, but has many other uses as well. With receptor sites in the brain, heart, and throughout the entire body, this steroidal hormone plays a pivotal role for men in maintaining lean body mass, skin elasticity, libido, and a healthy immune system. It ensures proper heart function, regulates mood and aids brain function (cognition), controls blood sugars, regulates healthy cholesterol levels, controls blood pressure, prevents heart attacks and even reduces risk of prostate cancer.

Low levels of testosterone in the body can cause:

  • Low energy
  • Loss of muscle mass, increased fat gain (especially belly fat)
  • Low sex drive
  • Moodiness
  • Morning stiffness, aches and pains
  • High risk for heart disease, diabetes, metabolic syndrome, and strokes
  • Brittle bones


Testosterone also aids bone growth and anabolic functions, as well as augmenting protein synthesis. Men produce more testosterone than women, evidenced by increased bone and muscle mass.

Gonadotropic hormones, released from the pituitary gland, impact testosterone and sperm production. Stimulating hormones become less effective as we age, making supplementation more significant with passing years. Testosterone production is initiated by the pituitary gland, deep within the brain. The gland secretes luteinizing hormone (LH), which stimulates Leydig cells in the testicles to produce testosterone.

Having low testosterone levels—with its subsequent health and emotional impact—can become a valid concern for men.

According to recent studies, low testosterone levels continue to be associated with increased mortality risk (Archives of Internal Medicine August 2006; Circulation August 2006; Journal of Clinical Endocrinology & Metabolism October 2007). Here are some ways that happens:

Obesity. Estrogen is stored in fat—and fat cells have sizeable amounts of the enzyme aromatase, which transforms converted testosterone into estrogen. These high levels of estrogen compete for receptor sites. Obesity presents more problems with potential cancer, heart disease, and diabetes concerns as well as the emotional ramifications of having a demasculinizing body. It should be noted that excessive alcohol use, specific drug interactions, and a zinc deficiency also can promote aromatization and subsequent high estrogen levels.

Diminished Leydig cells: Testosterone production, created via Leydig cells in the testicles, usually peaks in males in the late teens. Men have an estimated 700 million Leydig cells at birth, but that number declines by 6 million annually, after they reach 20 years old. Aging enters the picture, diminishing the number of these testosterone-producing cells.

Imagine walking into a dimly lit room. You look at the 300-watt light bulb and wonder why the room isn’t brighter. Is there something wrong with the rheostat—or the bulb? In younger men—30s, 40s and even early 50s—-the rheostat is the issue. The pituitary gland may slow down or stop producing the stimulating luteinizing hormone (LH). Testicles aren’t receiving a signal, so they don’t produce testosterone.

Simply giving these men direct testosterone supplementation usually is contraindicated. They might feel better, but the problem just became complicated because the added testosterone (in patients with low LH) shuts down the biofeedback mechanism, causing testicular atrophy. The appropriate therapy is to stimulate the LH, causing the testicles to produce more testosterone on their own. As a result, patients enjoy a more physiologic benefit, keeping testicles active.

The older man is another matter. The problem isn’t the rheostat: the bulb needs replacing. In this case, hormonal therapy restores levels to their age-appropriate norm.

And then for some men, the rheostat and the bulb are issues. When the rheostat is the problem, hormonal therapy helps relieve men from the devastating symptoms that negatively impact the male psyche, hinder intimate relationships, and affect work performance; such as decreased libido and poor sexual performance, thinning hair, increased body fat (especially abdominal or pectoral fat), reduced lean muscle tissue, lack of focus or drive, cognitive impairment and depression, and decreased bone mass.

High estrogen levels. Men need a certain amount of estrogen. But if the male body converts more testosterone to estrogen than required, the levels become too high. Consequently, the estrogen interferes with whatever free testosterone exists and both hormones compete for receptor sites. Aromatase (found in skin, brain, fat, and bone) transforms the hormone into estrogen (estradiol). As years pass, increasingly more testosterone converts to estradiol, leading to prostate cancer, heart disease, and stroke.

High conversion to DHT – A similar—but different—story unfolds for men in general. Through enzymatic action, testosterone can convert to dihydrotestosterone (DHT). The enzyme 5-alpha reductase (found in high concentrations in the prostate gland and skin) converts testosterone into DHT, leading to increased prostate size, hair loss, and increased risk for cancer.

High sex hormone binding globulin levels. Only about 2% of testosterone is free—but a critical amount of that must be unencumbered for full effectiveness. As men age, sex hormone binding globulins (SHGB) increase, which compete with estrogen and cause a decrease in free testosterone.

Incorrect testosterone measurement. Clinical indicators of declining testosterone may give a care provider the notion an individual may be a candidate for testosterone replacement. However, objective measures must be obtained to properly institute and manage therapy as well as rule out and address accompanying medical problems.

Both total and free testosterone studies should be measured to adequately evaluate testosterone levels. For males, 260-1,000 nanograms per deciliter (ng/dL) arc given as a normal laboratory range, for men aged 20-70. For females, this range is 15-70 ng/ dL. Free testosterone levels average approximately 2% of the total, 50-210 picograms per milliliter (pg/ml) for men and 1-10 pg/ml for women. Free testosterone is the more valuable of the two, reflecting the amount of hormone available to perform useful work.

Relying on a 50-year age span (from ages 20 to 70) is not useful. A decline of 70% from more youthful levels will produce the previously mentioned clinical problems, yet is declared “within normal range.” A more accurate approach is using the upper end of normal range, adjusted for age—then maintain these levels over time, rather than letting them continually decline. This is the healthy range.


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