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(tĕstŏs`tərōn), principal androgen, or male sex hormonehormone,
secretory substance carried from one gland or organ of the body via the bloodstream to more or less specific tissues, where it exerts some influence upon the metabolism of the target tissue.
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. One of the group of compounds known as anabolic steroidssteroids,
class of lipids having a particular molecular ring structure called the cyclopentanoperhydro-phenanthrene ring system. Steroids differ from one another in the structure of various side chains and additional rings. Steroids are common in both plants and animals.
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, testosterone is secreted by the testes (see testistestis
or testicle
, one of a pair of glands that produce the male reproductive cells, or sperm. In fetal life the testes develop in the abdomen, then descend into an external sac, the scrotum.
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) but is also synthesized in small quantities in the ovariesovary,
ductless gland of the female in which the ova (female reproductive cells) are produced. In vertebrate animals the ovary also secretes the sex hormones estrogen and progesterone, which control the development of the sexual organs and the secondary sexual characteristics.
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, cortices of the adrenal glandsadrenal gland
or suprarenal gland
, endocrine gland (see endocrine system) about 2 in. (5.1 cm) long situated atop each kidney. The outer yellowish layer (cortex) of the adrenal gland secretes about 30 steroid hormones, the most important of which are aldosterone and
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, and placenta, usually from cholesterolcholesterol
, fatty lipid found in the body tissues and blood plasma of vertebrates; it is only sparingly soluble in water, but much more soluble in some organic solvents. A steroid, cholesterol can be found in large concentrations in the brain, spinal cord, and liver.
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. 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 metabolismmetabolism,
sum of all biochemical processes involved in life. Two subcategories of metabolism are anabolism, the building up of complex organic molecules from simpler precursors, and catabolism, the breakdown of complex substances into simpler molecules, often accompanied by
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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 steroidanabolic steroid
or androgenic steroid
, any of a group of synthetic derivatives of testosterone that promote muscle and bone growth. Used to treat uncontrolled weight loss in wasting diseases, anabolic steroids have also been taken by bodybuilders and athletes seeking
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(also 17 β-hydroxyandrost-4-en-3-one), the principal male sex hormone; chemically, a steroid. Testosterone occurs as colorless crystals having a melting point of 155°C. It is sparingly soluble in water but soluble in organic solvents. (The substance was first obtained in 1935. Here, testosterone in crystalline form was isolated from bovine testis tissue, 100 kg of tissue yielding 10 mg of hormone.)

In humans and other higher vertebrates, testosterone is produced by the sex glands, mainly the testes, as well as by the adrenal glands, placenta, and liver. Intermediate products in the biosynthesis of testosterone include cholesterol and progesterone.

The normal level of testosterone in the blood of a man is 0.5–0.6 microgram per 100 milliliters; in a woman, the level is 0.12 microgram per 100 milliliters. A man produces approximately 15 mg of testosterone per day. Testosterone promotes the development of male sexual organs and of secondary sex characteristics. It affects the differentiation of sexual organs and bodily structures of vertebrates developing in the uterus. The concentration of testosterone in the blood probably serves as the factor determining masculinization in males and virilism in females. Other androgens are active only after their conversion into testosterone.

Testosterone is used in medicine in substitution therapy when there are insufficiencies in the functioning of sex glands in men. It is also used for climacteric disorders in women and for certain types of tumors. Intake of testosterone over prolonged periods blocks the secretion of gonadotrophic hormones and suppresses sexual activity. In the pharmaceutical industry, the hormone is obtained from sterols and steroid saponins. Highly active synthetic analogues of testosterone, such as testosterone propionate and methyltestosterone, are used in medical practice.


Fieser, L., and M. Fieser. Steroidy. Moscow, 1964. (Translated from English.)
Heftmann, E. Biokhimiia steroidov. Moscow, 1972. (Translated from English.)



C19H28O2 The principal androgenic hormone released by the human testis; may be synthesized from cholesterol and certain other sterols.


a potent steroid hormone secreted mainly by the testes. It can be extracted from the testes of animals or synthesized and used to treat androgen deficiency or promote anabolism. Formula: C19H28O2
References in periodicals archive ?
The authors thank the Novo Nordisk Foundation, Ipsen Scandinavia, for kindly providing Testim and placebo, and the Institute of Clinical Research-University of Southern Denmark.
That activist shareholder had argued that the company should abandon Nasulin to concentrate on Testim, but the end result is that the company might end up going to someone else.
Looking ahead, the company expects Testim sales in 2010 between $185 million to $195 million.
A total of 370,000 prescriptions were dispensed for Testim during that period.
Androgen creams (Androgel and Testim) are now available for daily topical use, minimising the peaks and trough side-effects of injectables.
La via transdermica consta de varios preparados: gel hidroalcoholico al 1% (Androgel) en dosis de 50, 75 o 100 mg diarios, Testogel o Testim que contienen 1% de testosterona y liberan 50 mg de hormona (34), parche escrotal (Testoderm) o no escrotal (Androderm, Testoderm TTS) e implantacion cutanea en forma de semilla o capsula de 200 mg cada 4 a 6 meses.
Otherwise, transdermal testosterone such as Androgel or Testim can be applied as indicated.
Testim is approved for use in treating men with low testosterone levels.
The validity of the resulting knowledge is demonstrated by the fact that it so often 'works in practice', as its countless achievements, from medicine to moon rockets, bear ample testim ony.
In the 1991 survey, seventy-five percent of the judges reported admitting all proffered expert testim ony.
Carol revealed on Twitter she took Oestrogel and Testim plus progesterone, saying: "From the moment I took it, I have never, ever felt that way."