views updated Jun 08 2018



Testosterone (tes-TOS-ter-own) is a white to creamy-white crystalline or powdery material that is odorless and tasteless and stable in air. It is a member of the organic family of compounds known as androgenic steroids—hormones responsible for the development of male sexual characteristics, such as male sex organs, a deep voice, and facial hair. Testosterone is present in both male and female bodies, although to a greater extent in men than in women.



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Carbon, hydrogen, oxygen


Steroid (organic)




288.41 g/mol


155°C (311°F)


Decomposes above melting point


Insoluble in water; soluble in ethyl alcohol, chloroform, vegetable oils, ether, and other organic solvents

The earliest studies of testosterone were conducted by French physiologist Charles E. Brown-Séquard (1817–94), sometimes called the father of endocrinology. Endocrinology is the study of hormones, their effects, and the glands that produce them. In 1889, at the age of 72, Brown-Séquard injected himself with extracts from dog and pig testes and reported a major change in his physical and mental health. He reported that he had regained the strength that he had as a younger man. He also said the extract improved his intellectual abilities. Brown-Séquard's scientific colleagues laughed off his discoveries, and studies of testosterone were largely suspended for almost half a century.

In the 1930s, however, interest in the compound was revived. In 1935, scientists obtained the first pure sample from testosterone and were able to confirm Brown-Séquard's findings. Within a matter of years, the compound became especially popular among middle-aged men who believed that it could restore their physical and mental abilities. Testosterone was first synthesized in 1935 by German chemist Adolf Friedrich Johann Butenandt (1903–1995), an accomplishment for which he was awarded the 1939 Nobel Prize in Chemistry.

Testosterone is also known by the following names; 17β-Hydroxyandrost-4-ene-3-one; androst-4-en-17β-ol-3-one; testosteroid; testosteron; testostosterone; and trans-testosterone.


Testosterone is produced naturally in the male testes and the female ovaries. It is also made synthetically starting either with cholesterol or diosgenin, a plant steroid.


Both males and females of all vertebrate species produce testosterone. The amount present in the male body is considerably greater than that present in the female body. Testosterone has a number of biological effects on the body, including an increase in the number of red blood cells and muscles cells and initiation of the development of male sex organs. It is also responsible for the development of secondary male sexual characteristics, such as the growth of body and facial hair, deepening of the voice, and increased sexual desire. Some less desirable effects are an increase in oiliness of the skin and acne.

Testosterone production in men tends to increase during childhood and reaches a maximum during the late teens or early twenties. It then decreases throughout the rest of a man's life. A sudden or extreme decrease in testosterone levels, caused by disease or injury to the hypothalamus, pituitary gland, or testes, can lead to a medical condition known as hypogonadism.

Interesting Facts

  • Women who choose to undergo a series of procedures to change their gender are required to take testosterone over a period of many months to stimulate the development of male sex characteristics. They must continue taking testosterone supplements for the rest of their lives.

Treatments for hypogonadism in the form of testosterone injections, tablets, skin patches, and skin gels are available. Some men use these devices in an attempt to revive masculine traits that begin to decline normally as one grows older. Many individuals believe, like Brown-Séquard, that testosterone can be something of a "miracle drug" that will restore their lost youth. It has at times been recommended also as a treatment for a host of medical problems, including infertility, impotence, lack of sex drive, osteoporosis, shortness of stature, anemia, and low appetite. Testosterone may or may not be helpful in treating any one of these conditions.

Since the 1950s, athletes have been using testosterone, its derivatives, and related compounds to improve their performance. The compound increases a person's bone and muscle mass, significantly improving his or her strength and endurance. Testosterone was first used on a large scale basis by athletes from the Soviet Union in the 1950s as part of that nation's efforts to become dominant in world sports.

One problem with using testosterone as a performance-enhancing drug is its undesirable side effects. It tends to increase the size of a man's prostate gland and decrease the size of his testicles. It may also produce wide mood swings that may include dangerously aggressive feelings.

Words to Know

A hormone responsible for the development of male sexual characteristics.
A chemical whose structure is based on or related to another chemical.
A chemical produced by living cells in a body that promotes the activity of other cells in the body.
A chemical reaction in which some desired chemical product is made from simple beginning chemicals, or reactants.

Because of these side effects, researchers have developed compounds that produce the same effects as those obtained from natural testosterone, but without the compound's harmful side effects. Some of those compounds increase the natural production of testosterone in the body when they are ingested. Others are derivatives of testosterone, compounds with similar chemical structures, but minor changes that reduce side effects. These derivatives include compounds such as dihydrotestosterone, androstenedione (also known as andro), dehydroepiandrosterone (DHEA), clostebol, and nandrolone. Today most derivatives of testosterone and testosterone-producing compounds are banned by sports organizations, both because of their harmful side effects and because of the unfair advantages they provide athletes who use them.


Hellstrom, Wayne J. G. "Testosterone Replacement Therapy." Digital Urology Journal. http://www.duj.com/Article/Hellstrom2/Hellstrom2.html (accessed on November 15, 2005).

"Material Safety Data Sheet: Testosterone." Paddock Laboratories, Inc. http://www.paddocklabs.com/forms/msds/testost.pdf (accessed on November 15, 2005).

"Testosterone." International Programme on Chemical Safety. http://www.inchem.org/documents/pims/pharm/pim519.htm (accessed on November 15, 2005).

"Testosterone Deficiency." Urology Channel. http://www.urologychannel.com/testosteronedeficiency/index.shtml (accessed on November 15, 2005).


views updated May 23 2018


Testosterone is the male sex hormone. Testosterone is a steroid hormone, with a chemical structure closely resembling that of the anabolic steroids used to produce increases of mass and strength among athletes. Testosterone is chemically classified as an androgen, one of the group of hormones that promote the growth and development of the male body characteristics, including greater muscle mass. The contrasting female growth hormones are estrogens, chemically similar to the male hormone. Because testosterone promotes the growth of male characteristics, it has been long desired as a muscle and strength building agent. While testosterone is essential in the creation of the physical distinctions between the male and female structures, the female endocrine system also produces testosterone, though in much lesser quantities than males.

Like all steroids, testosterone is constructed from four carbon rings; it is the location of various oxygen and hydrogen molecules within the ring structure that distinguishes testosterone from other well-known steroids used by athletes, including stanozolol, dianabol, and nandrolone.

Testosterone formation begins within the body as a process-utilizing cholesterol, itself a byproduct of the fats ingested through diet and absorbed for storage within the body as triglycerides. Within the body, cholesterol is used to form testosterone and numerous other hormones. As a hormone, testosterone is a product of the body's endocrine system, a sophisticated series of glands that are subordinate to the functions of the thyroid gland, which is itself directed in its actions by the region of the brain known as the hypothalamus. The hypothalamus/pituitary gland/testes glandular relationship is referred to as the gonadal axis. The testes produce between 4 mg and 7 mg of testosterone each day in a healthy male.

Hormones function as chemical signals directed by the brain to compel bodily organs or systems to function in a particular way. The release of adrenaline when a threat to the body is perceived and the production of the growth hormone during the period of adolescence are two common examples of hormone secretion and function. With testosterone, any disruption of the signals delivered along the gonadal axis will interfere with testosterone production.

Within the endocrine system, the primary source of testosterone production is the testes, the pair of male glands located inside the scrotum. The adrenal glands, positioned above each kidney, are a secondary source of this hormone. Testosterone is of fundamental importance to human function in a number of areas. Testosterone influences the development of all primary and secondary sexual characteristics in males, including their sexual function, and appearance attributes such as voice characteristics and the growth of body hair. The general speed and quality of male tissue growth is influenced by testosterone, as is the overall development and maintenance of muscle mass and strength. Adequate levels of testosterone production are necessary for the formation and preservation of bone structure and bone density. Testosterone contributes to effective brain activity, including learning and memory skills. Finally, testosterone contributes to the maintenance of the body's general energy levels necessary for effective function in all physical activities.

For males over 50 years of age, there is a natural decline in the amount of testosterone produced by the testes. This decline can present a significant difficulty for older male athletes, as reduced testosterone production will contribute to muscle weakness, a potential decrease in sexual function, as well as the decreased bone density that typically contributes to osteoporosis, the bone-thinning disease. The most widely used treatments for testosterone deficiency involve a hormone replacement therapy, which provides replacement testosterone to the body either through a transdermal (skin-applied) patch, or intramuscular injection.

In international athletic competition governed by the World Anti-Doping Agency (WADA), testosterone is specified as a banned substance on the Prohibited List of all illegal performance-enhancing substances. Testosterone is classed as an anabolic androgenic steroid, an illegal steroid that is intended to produce or facilitate male growth and physical characteristics in an athlete. Prior to the ascendancy of WADA in the late 1990s as the foremost drug regulatory agency in athletics, a number of notable world-class athletes had been the subject of positive testosterone tests, among them American sprinter Dennis Mitchell, American middle distance runner Mary Decker Slaney, and Dutch shot putter Erik de Bruin. Unlike other chemically produced performance-enhancing substances, testosterone is present in the body of all athletes in varying degrees. Testosterone testing is based on whether the hormone appears to be present in an unnatural amount, beyond the range that would typically be expected in that person. The WADA standard for the testosterone range is generally where the amount of testosterone present through testing is greater than 4:1 ratio to the expected levels; at those levels, a positive drug test is deemed to have resulted.

WADA have developed similar testing standards for all potentially endogenous substances (like testosterone, those capable of originating within the body), as opposed to the stricter limits defined for exogenous substances (those that can only originate outside of the body, such as most anabolic steroids and stimulants).

see also Anabolic steroids; HGH; Hormones; Nandrolone.


views updated May 18 2018



Synthetic derivatives of the natural hormone testosterone are used to reduce the size of hormone-responsive tumors.


Testosterone-related drugs are used to treat advanced disseminated breast cancer in women.


Testosterone belongs to a class of hormones called androgens. These are male hormones responsible for the development of the male reproductive system and secondary male sexual characteristics such as voice depth and facial hair. Testosterone is normally produced by the testes in large quantities in men. It also occurs normally in smaller quantities in women.

Several man-made derivatives of testosterone are used to treat advanced disseminated breast cancer in women, especially when cancer has spread to the bones. The most common of these testosterone-like drugs are fluoxymesterone (Halotestin) and methyltestosterone (Testred). These androgens are used only in women who have late-stage breast cancer and who meet specific criteria. These criteria include:

  • The patient is postmenopausal.
  • The tumors have been shown to be hormone-dependent.
  • The tumors have spread, often to the bone, or recurred after other hormonal cancer treatments.

Using testosterone derivatives to treat breast cancer is a palliative treatment. This means that the treatment helps relieve symptoms but does not cure the cancer. These drugs are approved by the United States Food and Drug Administration (FDA), and their cost is usually covered by insurance.

Clinical trials are currently underway that involve the use of testosterone-related androgens in varying combinations with other drugs to treat advanced cancers. The selection of clinical trials changes constantly. Current information on the availability and location of clinical trials can be found at the following web sites:

Recommended dosage

Dosage is individualized and depends on the patient's body weight and general health, as well as the other drugs she is taking and the way her cancer responds to hormones. Halotestin comes in tablets of 2 mg, 5 mg, or 10 mg. A standard dose of Halotestin for inoperable breast cancer is 10 to 40 mg in divided doses daily for several months. Tablets should be stored at room temperature. Testred comes in 10 mg capsules. A standard dose for women with advanced breast cancer is 50 to 200 mg daily.


Women who take testosterone derivatives for advanced breast cancer are postmenopausal, so the usual precautions about avoiding pregnancy when receiving androgen therapy do not apply.

Side effects

The most serious side effect of these drugs is hypercalcemia , a condition in which too much calcium circulates in the blood. This occurs because these drugs liberate calcium from bones. Calcium levels are monitored regularly, and the drug is discontinued if hypercalcemia occurs. Another serious (but less common) side effect is the development of tumors in the liver. Other side effects include deepening of the voice, development of facial hair and acne, fluid retention, and nausea.


As with any course of treatment, patients should alert their physician to any prescription, over-the-counter, or herbal remedies they are taking in order to avoid harmful drug interactions. Patients should also mention if they are on a special diet, such as low salt or high protein. They should not take calcium supplements, since testosterone already has the potential to increase circulating calcium to dangerous levels.

Testosterone derivatives may interact with anticoagulant drugs (blood thinners) such as Coumadin.

Tish Davidson, A.M.



A chemical produced by a gland in one part of the body that travels through the circulatory system and affects only specific receptive tissues at another location in the body.


Women have stopped menstruating, usually because of their age.


Egg-shaped male sexual organs contained in the scrotum that produce testosterone and sperm.


views updated May 29 2018


Testosterone is a male sex hormone, one of a class of compounds known as androgens . Included in this group are testosterone, dihydrotestosterone, and androstenedione. Androgens are synthesized from cholesterol and are considered steroid hormones, a category of hormones that includes female sex hormones such as estrogen . The isolation and synthesis of testosterone were reported in 1935. Chemists Adolf Butenandt and Leopold Ruzicka later received the Nobel Prize in chemistry (in 1939) for this work and related discoveries.

Testosterone (which is also present in small amounts in females) stimulates the growth of the male reproductive organs and promotes the development of the male secondary sex characteristics. It also affects body hair distribution, baldness, voice, and skin thickness and promotes each of the following: the formation of spermatozoa, protein formation, muscle development, bone growth, the retention of calcium, the rate of basal metabolism , and the number of red blood cells in the body.

In males testosterone is manufactured and secreted overwhelmingly by the testes. After secretion, 97 percent of testosterone is bound by protein carriers in blood and circulates in the body for thirty to sixty minutes. At this point, it has either been absorbed by various tissues or degraded to inactive molecules. Much of the testosterone absorbed by tissues is reduced to dihydrotestosterone, a step that is essential for the actualization of some of testosterone's effects. Testosterone not absorbed by tissues will be degraded by the liver, and the products of this degradation will be excreted from the body.

see also Estrogen; Steroids.

Matthew A. Fisher


Atkins, Peter W. (1987). Molecules. New York: W. H. Freeman.

Hoberman, John M., and Yesalis, Charles E. (1995). "The History of Synthetic Testosterone." Scientific American 272: 7682.


views updated May 14 2018

Testosterone ★★ 2003

Lurid black comedy about unrequited love, obsession, and revenge. When Pablo (Sabato) leaves Dean (Sutcliffe) without explanation after a torrid affair, Dean follows him to Argentina. There he gets mixed up with Pablo's intense circle of family and admirers. Some help, some hinder Dean in his attempt to confront his errant lover. Wicked take on gay romance with some tasty over-the-top performances, especially Braga as Pablo's mother. 105m/C DVD . US AR David Sutcliffe, Jennifer Coolidge, Sonia Braga, Celia Font, Antonio Sabato Jr., Leonardo Brezicki, Dario Dukah; D: David Moreton; W: David Moreton, Dennis Hensley; C: Ken Kelsch; M: Marco d'Ambrosio.


views updated May 11 2018

testosterone A steroid hormone, secreted by the testis, that in mammals and birds is the principal male sex hormone, responsible for the development of secondary sexual characteristics, It is also found in females as an intermediate in the synthesis of oestrogen.


views updated Jun 11 2018

testosterone The most potent of the male steroid sex hormones, which are collectively known as androgens. It is produced by the interstitial (Leydig) cells of the testis, and acts locally to stimulate development of sperm, and via the circulating blood to promote male characteristics. However, in many target tissues testosterone must first be converted to 5α-dihydrotestosterone (DHT) before it is active.

Saffron A. Whitehead

See sex hormones.


views updated May 21 2018

tes·tos·ter·one / teˈstästəˌrōn/ • n. a steroid hormone that stimulates development of male secondary sexual characteristics, produced mainly in the testes, but also in the ovaries and adrenal cortex.


views updated May 11 2018

testosterone (test-ost-er-ohn) n. the principal male sex hormone (see androgen), formed in the testis from androstenedione and converted in target cells to dihydrotestosterone, which mediates most of its actions. Preparations of testosterone are used for replacement therapy in males with testosterone deficiency.


views updated Jun 11 2018

testosterone Steroid hormone secreted mainly by the mammalian testis. It is responsible for the growth and development of male sex organs and male secondary sexual characteristics, such as voice change and facial hair.