testosterone


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testosterone

 [tes-tos´tĕ-rōn]
the principal male sex hormone (androgen) that is produced by Leydig's cells of the testes in response to luteinizing hormone secreted by the pituitary gland. It is also produced by the adrenal cortex in both males and females. Its chief function is to stimulate the development of the male reproductive organs, including the prostate, and the secondary sex characters, such as the beard. It encourages growth of bone and muscle, and helps maintain muscle strength.



Testosterone is obtained for therapeutic purposes by extraction from animal testes or by synthesis from cholesterol in a laboratory. It is used to treat male hypogonadism and delayed male puberty as well as to relieve symptoms in some forms of metastatic breast cancer in females, and is used as the base for various esters (e.g., cypionate, enanthate, propionate). Women normally secrete a certain amount of male hormones; however, if the hormone balance is disturbed and there is overproduction of male hormones in a woman, masculinization may develop.

tes·tos·te·rone

(tes-tos'tĕ-rōn),
The most potent naturally occurring androgen, formed in greatest quantities by the interstitial cells of the testes, and possibly secreted also in small amounts by the ovary and adrenal cortex; may be produced in nonglandular tissues from precursors such as androstenedione; used in the treatment of hypogonadism, cryptorchism, certain carcinomas, and menorrhagia. Various preparations are used therapeutically.

testosterone

/tes·tos·te·rone/ (tes-tos´tĕ-rōn″) the principal androgenic hormone, produced by the interstitial (Leydig) cells of the testes in response to stimulation by the luteinizing hormone of the anterior pituitary gland; it is thought to be responsible for regulation of gonadotropic secretion, spermatogenesis, and wolffian duct differentiation. It is also responsible for other male characteristics after its conversion to dihydrotestosterone. In addition, testosterone possesses protein anabolic properties. It is used as replacement therapy for androgen deficiency in males, in the treatment of delayed male puberty or hypogonadism, and in the palliation of certain breast cancers in females; used as the base or various esters (e.g., cypionate, enanthate, propionate).

testosterone

(tĕs-tŏs′tə-rōn′)
n.
1. A steroid hormone, C19H28O2, produced primarily in the testes and responsible for the development and maintenance of male secondary sex characteristics. Testosterone synthesized from plant sources, often in the form of an ester, is used in the medical treatment of testosterone deficiency.
2. Any of several synthetic compounds that mimic the physiologic activity of testosterone, used as drugs in the medical treatment of testosterone deficiency and as doping agents by athletes.

testosterone

[testos′tərōn]
a naturally occurring androgenic hormone.
indications It is prescribed for androgen deficiency, for female breast cancer, and for stimulation of growth, weight gain, and red blood cell production.
contraindications Cancer of the male breast or prostate, liver disease, pregnancy or suspected pregnancy, or known hypersensitivity to this drug prohibits its use.
adverse effects Among the more serious adverse effects are hepatic dysfunction, fluid retention, masculinization, acne, and erythrocythemia.

testosterone

 Endocrinology The principal and most potent of the C-19 androgenic steroids, produced from its precursor hormone, progesterone, by the Leydig cells of testis, and, in far lesser amounts, in the ovary and adrenal cortex, and drives the development and maintenance of ♂ sex characteristics Activity Nitrogen retention, buildup of protein, induction and maintenance of 2º ♂ characteristics–eg, facial hair; testosterone secretion is in turn regulated by LH, which is produced by the anterior pituitary Indications Treatment of sexual dysfunction, weight loss, depression Ref range ♂–total, 300–1000 ng/dL; free, 5.1–41.0 ng/dL; ♀–total, 20-90 ng/dL; free, 0.1–2.3 ng/dL ↑ in ♂ sexual precocity, hyperplasia of adrenal cortex, adrenogenital syndrome, polycystic ovary syndrome ↓ in Alcoholism, anterior pituitary gland hypofunction, estrogen therapy, Klinefelter syndrome–aka 1º hypogonadism, testicular hypoactivity. See Sublingual testosterone. Cf Progesterone.

tes·tos·ter·one

(tes-tos'tĕ-rōn)
The most potent naturally occurring androgen, formed in greatest quantities by the interstitial cells of the testes and possibly secreted also by the ovary and adrenal cortex of the suprarenal gland; used in the treatment of hypogonadism, cryptorchism, certain carcinomas, and menorrhagia.
Compare: bioregulator

testosterone

The principal male sex hormone (androgen) produced in the INTERSTITIAL cells of the TESTIS and, to a lesser extent in the OVARY. Testosterone is ANABOLIC and stimulates bone and muscle growth and the growth of the sexual characteristics. It is also used as a drug to treat delayed puberty or some cases of infertility or to help to treat breast cancer in post-menopausal women. It may be given by mouth, depot injection or skin patch. The drug is on the WHO official list. Brand names are Andropatch, Restandol, Sustanon, Testogel and Virormone.

testosterone

a steroid ANDROGEN produced by the LEYDIG CELLS between the SEMINIFEROUS TUBULES of the TESTIS. It causes the development and maintenance of accessory sex organs, the genitalia and the SECONDARY SEXUAL CHARACTERS.

Testosterone

Male hormone produced by the testes and (in small amounts) in the ovaries. Testosterone is responsible for some masculine secondary sex characteristics such as growth of body hair and deepening voice.

anabolic steroids

usually refers to a group of synthetic drugs based on the male sex hormone testosterone secreted by the testes, and having similar anabolic and other androgenic actions to this and other androgens from the adrenal cortex in both sexes. These drugs are misused in sports, especially where enhanced power and strength are beneficial such as weight lifting and cycling. Used in conjunction with a training programme, they lead to an increase in muscle size and power. They may also lessen fatigue and improve tissue repair. Use in children can lead to premature fusion of the epiphyses, stunting skeletal growth. Side effects are common and potentially serious. They include psychological changes (notably aggression), liver damage, cardiovascular (raised blood pressure) and endocrine effects (masculinization in females, testicular atrophy and reduced sperm count in males.) See also adrenal glands, hormones; Table 1.
Table 1: Hormones
Site of productionName of hormoneMain targetsInvolved in regulating:Secretion controlled by:
HypothalamusReleasing and inhibiting hormonesAnterior pituitary (via local blood vessels)Secretion of anterior pituitary hormonesOther brain regions; feedback re regulated hormones and their actions
Neurohormones released from posterior pituitary:
OxytocinUterus, breastsLabour and lactationAfferent information from target organs
Antidiuretic hormone (ADH, vasopressin)KidneysWater loss: ECF volume and osmolalityHypothalamic osmoreceptors
Anterior pituitary(Human) growth hormone (H)GHMost cellsGrowth and metabolismHypothalamic releasing and inhibiting hormones via local blood vessels
ProlactinBreastsMilk production
Trophic hormones:
Thyroid-stimulating (TSH)Thyroid glandThyroid secretions
GonadotrophinsOvary or testisGerm cell maturation and hormone secretions
Adrenocorticotrophic (ACTH)Adrenal cortexCortisol secretion
Pineal bodyMelatoninWidespread, including brain, thymus, etc.
  • Sleep/wake cycle
  • Antioxidant
  • Immune system
Hypothalamus; varying light input from retina
Thyroid
  • Thyroxine
  • Triiodothyronine
  • Calcitonin
  • Most cells
  • Bone, kidneys, gut
  • Cellular oxidative metabolism
  • Decreases ECF [Ca2+]
  • TSH from anterior pituitary. Negative feedback from blood hormone concentration
  • ECF [Ca2+]
ParathyroidsParathormoneBone, kidneys, gut
  • Calcium and phosphorus absorption, secretion and turnover in bone.
  • Increases ECF [Ca2+]
ECF [Ca2+]
Adrenal: Cortex
  • Cortisol
  • Aldosterone
  • Androgens
  • Most cells
  • Kidneys
  • Gonads & other tissues
  • Metabolism
  • Response to stress
  • Na and K balance
  • Sex characteristics and reproductive function
  • ACTH from anterior pituitary
  • ECF [Na+] [K+]
  • Renin-angiotensin
  • ACTH
Medulla
  • Adrenaline
  • Noradrenaline
Heart, smooth muscle, glandsCardiovascular and metabolic adjustments to activity and stressSympathetic nervous system
Atrial wallAtrial natriuretic hormoneKidneysBlood volume; increases sodium (therefore also water) loss in urineStretch of atrial wall by venous pressure
Gonads: TestisAndrogens (mainly testosterone)Genitalia and other tissuesReproductive function and sex characteristicsAnterior pituitary gonadotrophins
Ovary
  • Oestrogens
  • Progesterone
Uterus, breasts and other tissuesMenstrual cycle, pregnancy, lactation
Pancreas
  • Insulin, glucagon
  • Somatostatin
  • Most cells
  • Other secretory cells in the pancreas
Blood levels, storage and cellular uptake of nutrients, notably glucose, but also proteins and fatsBlood levels of nutrients; autonomic nervous system; other gastrointesinal hormones
Alimentary tract
StomachGastrinGastric acid-secreting cellsGastrointestinal functions: motility, digestive juices and other secretionsLocal chemical and mechanical factors in the alimentary tract
Small intestine
  • Secretin
  • Cholecystokinin- pancreozymin (CCK-PZ)
  • Somatostatin, motilin
  • Other peptide hormones including vasoactive intestinal peptide (VIP)
  • Widespread on
  • GI tract
Several GI functions including bile flow, pancreatic enzyme and exocrine secretionsIngestion of food, distension of GI tract

testis

the male gonad, the site of spermatogenesis, whence sperm are discharged via the vas deferens into the urethra at ejaculation. This and also testicular endocrine function (secretion of testosterone and related hormones) are under the control of gonadotrophic hormones from the anterior pituitary, and in turn of the hypothalamus.

testosterone

male hormone (released primarily from interstitial cells of testes), but also from adrenal cortex and ovaries, in much smaller amounts

tes·tos·ter·one

(tes-tos'tĕ-rōn)
Most potent naturally occurring androgen, formed in greatest quantities by interstitial cells of testes; used to treat some carcinomas, and other conditions.

testosterone

the most important male sex hormone (androgen) produced by the Leydig cells of the testes in response to luteinizing hormone (LH) secreted by the pituitary. Its chief function is to stimulate the development of the male reproductive organs and the secondary sex characters, such as the crest. It is necessary for the appearance of normal male sexual behavior. It encourages growth of bone and muscle, and helps maintain muscle strength. It is occasionally secreted in large amounts also by granulosa-theca cell tumors of the ovary, especially in mares.

testosterone cyclopentylpropionate, testosterone cypionate, testosterone propionate
esters with a long period of activity.
testosterone-responsive dermatosis
a bilaterally symmetrical alopecia, primarily affecting the flanks, ventral abdomen and caudomedial aspect of the thighs of male dogs. The cause is believed to be hypotestosteronism.
References in periodicals archive ?
Testosterone gel 1% is contraindicated in women who are or may become pregnant, or who are breast feeding.
What the FDA and conventional medical community still do not comprehend is that when natural testosterone is administered to men, it is imperative that estradiol blood levels be tested to ensure that the testosterone is not converting to excess estrogen.
It is not known if FORTESTA Gel and Testosterone Gel are safe or effective in children younger than 18 years old.
Among both groups, all biochemical recurrences were seen in men with high-risk features (Gleason score 8 or higher, positive surgical margins or lymph nodes), suggesting that the characteristics of the cancer themselves drive recurrences versus testosterone levels or replacement.
For most men (and women), however, fatigue has nothing to do with testosterone levels.
A drug company, AbbVie, maker of AndroGel, stated that testosterone has been found to improve health and lower the risk of death.
Commonly used testosterone medications include Androgel, Depo-Testosterone, Axiron, Testim, Androderm, Fortesta, Delatestryl, Methiest, Testred, Android and Straint.
Older men who had testosterone in the middle range survived longer than their counterparts who had either low or high levels of the hormone," the study's lead author, Bu Beng Yeap, MBBS, FRACP, PhD, of the University of Western Australia, based in Fremantle Hospital, Western Australia, said.
This in turn suggests that the current approach to assessing and managing the condition--a onetime measurement of serum testosterone only, an across-the-board designation of a "low" level, and simple replenishment with endogenous testosterone only--should be replaced by more rational, nuanced approaches, said Dr.
Steve Braun, a writer hired to generate articles supporting the use of testosterone therapy in various publications, described ghostwriting an article to appear under an endocrinologist's byline, for Life After 50 magazine.
The measurement of testosterone plays an important part in the diagnosis and treatment of many conditions in males and females of all ages.
propose that the reduction in Hsd17b2 expression in the protective labyrinth zone may allow more testosterone to reach the fetus and play a role in fetal programming of hypertension.