Testosterone

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, testosterone plays a pivotal role for men and women in maintaining lean body mass, skin elasticity, libido and healthy immune system.  Testosterone ensures proper heart function, regulates mood and aids brain function (cognition), controls blood sugars, regulates healthy cholesterol, controls blood pressure, prevents heart attacks and even reduces risk of prostate cancer.

Testosterone also aids in bone growth and anabolic functions, as well as augmenting protein synthesis.  The fact that men produce more testosterone than woman is evidenced by the 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 significant with passing years.

Women, men & testosterone.  In the female,testosterone is produces in the ovaries and the adrenal glands.  If a woman is thrown into surgical menopause (by having her ovaries removed), she abruptly loses 50% of her natural testosterone—along with 80% of her natural estrogens.

Ebbing estradiol and progesterone levels after entering menopause are compounded by falling testosterone and thyroid hormone.  A declining testosterone is bound to spark bodily changes:  a flux in metabolism, altered libido, effects on breasts, vagina, bones, blood vessels, gastrointestinal tract, cardiovascular system, skin, mental acuity.

Women, like men, need adequate testosterone for peak mental acuity, healthy bone density and muscle tissue.

Testosterone also helps prevent unwanted fat, heart disease and cognitive decline.  Without testosterone, women would have a 50% chance of experiencing pathological hip or vertebra fracture.  Especially frightening is that 20% of hip fracture patients die within a year of their surgery.

On the male side, 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 some men.

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

• Estrogen: Men need a certain amount of estrogen.  But if a 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.  In these cases, there are ways of blocking the estrogen---problem easily solved.

A similar—but different—story unfolds for men in general.  Through enzymatic action, testosterone can convert to DHT (dihydrotestosterone) and estrogen.

The enzyme 5-alpha reductase (found in high concentrations in the prostate gland and skin) converts testosterone into DHT.  Aromatase (found in skin, brain, fat and bone) transforms testosterone  into estrogen (estradiol), leading to prostate cancer, heart disease and stroke.

• Sex hormone binding globulin: 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 globulin (SHBG) increase, which compete with estrogen and cause a decrease in free testosterone.

• Obesity:  Estrogen is stored in fat—and fat cells have sizeable amounts of that enzyme discussed earlier, 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 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.

Younger men face different problems than older ones, when it comes to low testosterone levels.  Imagine walking into a dimly lit room.  You look at 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 testicle 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 ten for some men, the rheostat and the bulb are the issues.

When the rheostat is the problem, testosterone therapy helps relieve men from the devastating symptoms that negatively impact the male psyche, hinder intimate relationships and affect work performance, decreased libido and poor sexual performance, thinning hair, increased abdominal or pectoral fat, reduced lean muscle tissue, lack of focus or drive, cognitive impairment and depression, and decreased bone mass.

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 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 ng/dL are given as a normal laboratory range, for men ages 20-70.  For females, this range is 15-70 ng/dL.  Free testosterone levels average approximately 2% of the total, 50-210 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 50 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.

The Rejuvenate approach arrests falling testosterone levels and prevents its decline.  Testosterone levels provide enough clinical information to decide whether replacement is indicated.  Ideally, they should be considered in context of other hormonal and laboratory studies.  A Prostate Specific Antigen (PSA) measurement and Digital Rectal Exam (DRE) must accompany testosterone testing at your initial evaluation:  (1) as screens for preexisting prostate disease, (2) to direct further medical evaluation should elevated levels or abnormal exam be detected and (3) for use as a baseline in follow-ups.

A complete endocrine profile is necessary to create the most effective testosterone supplementation program, including thyroid hormones, luteinizing hormone (LH), estrogen, dihydrotestosterone (DHT), dihydroepiandrosterone (DHEA), blood count, lipid profiles and other laboratory and metabolic marker tests (such as body composition and bone density).  Once therapy begins, follow-up tests for testosterone (and other markers) must be monitored, ensuring adequate safety and effectiveness.