This article discusses the hormone Testosterone: how it is made, used by the body, and the different forms it takes. It was written for the causal reader, as well as people that are interested in testosterone replacement, anabolic steroids, DHEA, and amarase inhibitors.

Figure 1 shows the trail of Testosterone. Except for LH and FSH, all of the hormones discussed here are made in the testicles of men or the ovaries of women, and in the adrenal glands (on top of the kidneys).

Cholesterol
Except for LH and FSH, all of the hormones discussed here begin with cholesterol. The chain starts with two small changes to give:

DHEA (dihydroepiandrosterone), which is changed to Androstenedione. This chemical is then either changed to Testosterone or Estrogen. These chemical names are familiar to many athletes because of a belief they enhance muscle strength and endurance. A recent review of Google Scholar using DHEA and Androstenoeione as keywords reveled hundreds of studies, with some showing increases in Testosterone, Estrogen, strength or endurance, and others showing no effects.

Each change from one chemical to another requires the presence of another chemical, named enzymes. Enzymes are recyclable: they cause the change to occur quicker, and are not used up when they cause the change. Most of the enzymes at work here are not important to the understanding of which hormone does what. There is one exception.

The aromatase enzyme complex changes Androstenedione to Estrogen (Estrone). The term aromatase is familiar to anabolic steroid users, as they believe the use of an aromatase inhibitor will increase Testosterone levels.

Testosterone
For both men and women, Testosterone determines muscle straight and size, bone density, and sexual desire. The highest levels are seen in the early morning in younger people. Vasectomy (cutting the sperm tubes attached to the testicles) does not effect Testosterone levels. Removal of the ovaries results in a significant reduction in Testosterone.

Anabolic Steroids are synthetic Testosterones. They can be prescribed by doctors and physician assistants to increase low levels of natural Testosterone in older men and women, after surgical removal of the testicles or ovaries, or to supplement abnormally low levels found in some generic conditions. Anabolic Steroids can also be made illegally for use by athletes, who take them to increase muscle size, streghnt, and endurance.

Increasing the Testosterone levels above the normal values by the use of Anabolic Steroids for long periods of time can cause many different conditions. These include acne, advanced baldness, heart disease, diabetes, high blood pressure, aggressive behaviors, and sleep apnea.

Testosterone levels increase when Estrogen and thyroid hormone levels are low. The levels of Testosterone can also be increased above normal limits by certain medications:

-  Metoclopamide (Reglan), a medication used in GERD to increase the strength of the upper spincter of the stomach, and to increase emptying times in slow stomach (a common problem with diabetes),
-  Aldomet, an old medication used to lower high blood pressure, and
-  Danazol, an anticancer drug used for breast cancer.

Testosterone levels can be lowered by certain other medications.

-  Cimetidine (Tagamet). This medication lowers stomach acid, and so is used in GERD and with gastric ulcers.
-  Spironolactone (Aldactone), a water pill (diuretic) that conserves potassium,
-  Finasteride (Proscar), a drug that blocks the enzyme named 5-alpha-reductase, which changes Testosterone to Dihydrotestosterone. It is Dihydrotestosterone that effects the prostate gland, so less levels of Dihydrotestosterone causes the prostate to shrink over months. If you are a guy over 50 years old, you can appreciate having a safe drug that returns your urination stream to your younger days. The last is:
-  Finasteride (Propecia). You may notice that Finasteride is also the chemical name of Proscar, discussed above. The Proscar is 5 milligrams of Finasteride, while the Propecia is 1 milligram. Propecia is used for stopping male pattern baldness by blocking the same enzyme as Proscar. (Yes, Proscar also blocks male pattern baldness, but the lower dosage of Propecia seems to be too low to effect the prostate.)

Free Testosterone refers to the percent of Testosterone that is not tied (bound) to one of two protiens in the blood. It is thought to be the most active form of Testosterone. It begins to decrease in men at about age 40, while overall Testosteone levels do not begin to decrease in average men until age 70 (although some men experience the beginning of lower levels as young as 40 years old).

Dihyrotestosterone (DHT) is one of the hormones that come directly from the break down of Testosterone (the other is Estrogen).

What is the difference between DHT and Testosterone? Testosterone effects the testicles, brain, and kidneys. If Testosterone is low, the testicles are small, sexual desire is markedly reduced, and the kidneys are smaller than normal. (The kidneys are larger in men because they have more waste products from bigger muscles).

5-alpha-reductase is the name of the enzyme that changes Testosterone to DHT (See Finasteride above). DHT effects include hair (beard, thicker body hair), bone (thicker), muscles (larger), skin (thicker), semen, and the prostate gland (maintains normal function).

Estrogen is the other hormone that Testosterone can be changed into. The word Estrogen actually refers to three different hormones with simiar effects. The strongest of the three is Estradiol, while the other two weaker Estrogenic hormones are Estrone and Estriol.

When the Estrogenic hormones are higher than normal in men, DHT levels are lower. So men who are exposed to Estrogen like chemicals (marijuana, some pestisides, birth control pills, and others) have thinner, softer skin, enlarged breasts, make less semen and have lower sperm counts.

Just as men make more DHT from Testosterone, women make more Estrogen. It is Estrogen (and the next hormone below, Progesterone) that regulates menstral periods and maintains pregnancies. Both of these female hormones decrease and then are no longer made in menopause.

Progesterone's effects are well known in women, but little is known what effects this hormone has in men.

We hope this information was helpful. Email your comments to jkircherpa@aol.com.