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Testosterone

Testosterone

Definition

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

Purpose

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

Description

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.

Precautions

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.

Interactions

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.

KEY TERMS

Hormone

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.

Postmenopausal

Women have stopped menstruating, usually because of their age.

Testes

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

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Testosterone

Testosterone


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

Bibliography

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.

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"Testosterone." Chemistry: Foundations and Applications. . Retrieved August 24, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/news-wires-white-papers-and-books/testosterone

testosterone

testosterone (tĕstŏs´tərōn), principal androgen, or male sex hormone. One of the group of compounds known as anabolic steroids, testosterone is secreted by the testes (see testis) but is also synthesized in small quantities in the ovaries, cortices of the adrenal glands, and placenta, usually from cholesterol. Testosterone is necessary in the fetus for the development of male external genitalia; increased levels of testosterone at puberty are responsible for further growth of male genitalia and for the development and maintenance of male secondary sex characteristics such as facial hair and voice changes. Testosterone also stimulates protein synthesis and accounts for the greater muscular development of the male (see metabolism).

An abnormally low testosterone level in men, known as hypogonadism, is treated with testosterone, but it is not clear if testosterone is a safe or effective treatment for so-called low testosterone, such as the lower levels of testosterone typically found in older men. In men with lower testosterone, the level can often be raised by increasing exercise, improving diet, and reducing weight to the recommended range. For many years, synthetic steroids similar to testosterone have been used by athletes with the goal of improving performance, but medical research has shown that these drugs may have a wide range of harmful side effects and their use is now typically banned (see anabolic steroid).

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testosterone

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.

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testosterone

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.

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testosterone

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.

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testosterone

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.

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testosterone

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.

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testosterone

testosterone The principal male sex hormone. See androgen.

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testosterone

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