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What are androgens?

Hormones are chemical messengers madeby glands in the body that are carried inthe blood to act on other organs in thebody. Hormones are needed for growth,reproduction and well-being.

Androgens are male sex hormones thatincrease at puberty and are needed for aboy to develop into a sexually mature adultwho can reproduce. The most importantandrogen is testosterone.

Testosterone is the most important androgen(male sex hormone) in men and it is neededfor normal reproductive and sexual function.Testosterone is important for the physicalchanges that happen during male puberty,such as development of the penis and testes,and for the features typical of adult mensuch as facial and body hair. Testosterone alsoacts on cells in the testes to make sperm.

Testosterone is also important for overallgood health. It helps the growth of bonesand muscles, and affects mood and libido(sex drive). Some testosterone is changed intooestrogen, the female sex hormone, and thisis important for bone health in men.Testosterone is mainly made in the testes. Asmall amount of testosterone is also made bythe adrenal glands, which are walnut-sizedglands that sit on top of the kidneys.

The pituitary gland and the hypothalamus,located at the base of the brain, controlthe production of male hormones andsperm. Luteinizing hormone (LH) andfollicle stimulating hormone (FSH) arethe two important messenger hormonesmade by the pituitary gland that act onthe testes.

LH is needed for the Leydig cells in thetestes to make testosterone, the male sexhormone. Testosterone and FSH from thepituitary gland then act together on theseminiferous tubules (sperm-producingtubes) in the testes to make sperm.

Androgen, or testosterone, deficiency iswhen the body is not able to make enoughtestosterone for the body to functionnormally. Although not a life-threateningproblem, androgen deficiency can affectyour quality of life.

Androgen deficiency due to diseases of thetestes or hypothalamus-pituitary affectsabout one in 200 men under 60 years ofage. It is likely that androgen deficiency isunder-diagnosed and that many men aremissing out on the benefits of treatment.About one in 10 older men may have testosterone levels lower than those inyoung men, but this is usually linked withchronic illness and obesity. The benefits oftestosterone treatment for such men arenot yet known.

Testosterone levels in men are highestbetween the ages of 20 and 30 years. Asmen age there is a small, gradual drop intestosterone levels; they may drop by up toone third between 30 and 80 years of age.

Some men will have a greater drop intestosterone levels as they age, especiallywhen they are obese or have other chronic(long-term) medical problems. On the otherhand, healthy older men with normal bodyweight may not experience any drop inserum testosterone levels.

There is no such thing as male menopauseor andropause that can be compared tomenopause in women.

Low energy levels, mood swings, irritability,poor concentration, reduced muscle strengthand low sex drive can be symptoms ofandrogen deficiency (low testosterone).Symptoms often overlap with those of otherillnesses. The symptoms of androgen deficiencyare different for men of different ages.

Androgen deficiency can be caused bygenetic disorders, medical problems, ordamage to the testes or pituitary gland.Androgen deficiency happens when thereare problems within the testes or withhormone production in the brain. A commonchromosomal disorder that causes androgendeficiency is Klinefelters syndrome.

A diagnosis of androgen deficiency involveshaving a thorough medical evaluation andat least two blood samples (taken in themorning on different days) to measurehormone levels. Diagnosis should not be simply based on symptoms as these could becaused by other health problems that needdifferent treatment. A diagnosis of androgendeficiency is only confirmed when blood testsshow a lower than normal testosterone level.

A reference range is used as a guide bytesting laboratories and doctors to decide whether a persons hormone levels arenormal or low, and whether treatment is needed. Testosterone is measured in units called nanomalor. The normal testosterone reference range for healthy, young adult men is about 8 to 27 nanomolar but these numbers vary between measurement systems.

Androgen deficiency is treated with testosterone therapy; this means giving testosterone in doses that return the testosterone levels in the blood to normal. Testosterone is prescribed for men with androgen deficiency confirmed by blood tests. Once started, testosterone therapy is usually continued for life and the man needs to be checked regularly by a doctor.

In Australia testosterone therapy is available in the form of injections, gels, lotions, creams, patches and tablets, and works very well for men with confirmed androgen (testosterone) deficiency. The type of treatment prescribed can depend on patient convenience, familiarity and cost.

Commercial testosterone products contain only the natural testosterone molecule that is chemically produced from plant materials.

Side-effects are not expected because testosterone therapy aims to bring a mans testosterone levels back to normal. However, testosterone therapy can increase the growth of the prostate gland which can make the symptoms of benign prostate enlargement (such as needing to urinate more often) worse. In the case of prostate cancer, testosterone therapy is not used because of concerns that it can make the tumour grow.

Too high a dose of testosterone can lead to acne, weight gain, gynaecomastia (breast development), male-pattern hair loss and changes in mood. Any side-effects should be managed by a doctor and the testosterone dose lowered.

There are many herbal products marketed, particularly on the Internet, as treatmentsthat can act like testosterone and improve muscle strength and libido (sex drive). However, there are no known herbal products that can replace testosterone in the body and be used to treat androgen deficiency.

Testosterone therapy generally stops the production of the pituitary hormones FSH and LH, which reduces the size of the testes and can lower or stop sperm being made.

Testosterone treatment should not be given to a man wanting to become a father in the foreseeable future. If sperm production was normal before testosterone therapy, it usually recovers after treatment stops but it can take many months to go back to normal.

Testosterone therapy in men with androgen deficiency aims to bring testosterone levels back to normal and to return muscle strength and energy levels back to normal. However, the use of androgens (anabolic steroids) by normal men to improve athletic performance is illegal and has important short-term and long-term health risks.

Men who use anabolic steroids will lower or even turn off their own testosterone and sperm production. It may take many months for testosterone levels and sperm counts to return to normal after stopping anabolic steroids.

There are no known ways to prevent androgen deficiency caused by damage to the testes or pituitary gland. However, if you live a healthier lifestyle and manage other health problems your testosterone levels may improve, if your low testosterone levels are caused by other illness.

Not all men have a drop in testosterone levels with age. A healthy lifestyle may help you to keep testosterone levels normal.

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Androgen (testosterone) deficiency | Andrology Australia

Testosterone is a major sex hormone produced in the testes of men. The pituitary gland is responsible for controlling the production of testosterone hormone. In the testes, luteinizing hormone binds to receptors on Leydig cells; this stimulates production and secretion of testosterone. Testosterone helps to develop the primary and secondary sexual characteristics in males. Development of sex organs, deeper voice, muscle mass, and facial hair all result from the sufficient production of this hormone. Testosterone deficiency as happens with age needs effective testosterone treatment.

Along with the development of sexual features, testosterone hormone also controls the following actions in a body:

With age, testosterone production declines, thus disturbing overall body functioning. Low levels of testosterone hormone lead to a condition termed as hypogonadism that can be treated with testosterone replacement therapy. Hypogonadism can be divided into two categories depending on the occurrence of pathology.

Primary Hypogonadism: It occurs at testicular level with high release of follicle stimulating hormone (FSH), luteinizing hormone (LH), and low release of testosterone.

Secondary Hypogonadism: It occurs at pituitary hypothalamic level with low or in some cases normal release of luteinizing hormone and follicle stimulating hormone along with low levels of testosterone hormone.

Testosterone replacement therapy effectively works to improve upon the conditions of primary and secondary hypogonadism.

Along with aging, there are some other factors that contribute toward low testosterone production and make a man go for testosterone treatment.

Deficient testosterone hormone levels can lead to many undesirable symptoms, like poor libido, lack of vitality, erectile dysfunction, declining muscle mass, osteoporosis, loss of body hair, depression, lower blood hemoglobin, memory loss, poor concentration, mood swings, mild anemia, disturbed cholesterol profile and a decrease in cognitive function that effects all of your activities. Testosterone therapy is the only possible way to cope with testosterone deficiency.

Before start of the testosterone treatment, there should be the right detection of the hormone deficiency. If you consult an expert doctor for testosterone therapy, he may prescribe you the blood test in the morning because testosterone levels are at peak during that time.

We, at Nationwide Synergy Inc, provide patients with best available options to treat their hormone deficiency.

Choosing one best option for testosterone therapy requires consultation with your physician. We have qualified physicians and doctors at our panel who provide expert guidance to the patients.

Stay Young and Healthy with Balanced Hormones Testosterone Replacement Therapy Is Your best Choice!

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Testosterone Replacement Therapy - Testosterone Treatment

Dr. Matthias Heck, Dr. Silvia Thne und Dr. Christof Winter(from left to right). Image: Andreas Heddergott / TUM

When bacteria develop antibiotic resistance, treatment with these medications becomes ineffective. Similarly, tumor cells can also change in such a way that renders them resistant to particular medications. This makes it vitally important for cancer patients and their doctors to determine as early as possible whether a specific therapy is working or not. A new blood test developed by researchers at the Technical University of Munich (TUM) can predict drug resistance in patients with advanced prostate cancer.

Prostate cancer tumor cells require the androgen hormone, testosterone, to grow. They possess a receptor to which testosterone binds and then signals the cancer cells to divide and grow. If a prostate tumor has already grown to a large size and started spreading throughout the body, therapeutic drugs are used to block the growth at its molecular origin either by targeting tumor cell receptors to prevent testosterone from binding, or by entirely blocking the bodys overall production of testosterone. Two of the drugs most frequently used in this type of therapy are abiraterone and enzalutamide.

THE HUNT FOR RESISTANT TUMOR CELLS

During the course of treatment, however, some tumor cells develop resistance to these drugs, and continue to grow and metastasize. The culprit: the tumors testosterone receptors have changed their structure, and the new variant can signal the cancer cells to continue dividing and spreading even without testosterone. The most common receptor variant seen in patients is called AR-V7. If we know in advance whether or not a tumor has developed cells with this receptor, we can provide advice on an individual basis at an early stage this can spare seriously-ill patients from undergoing an ineffective therapy, explains Assistant Professor Dr. Matthias Heck, co-leader of the study and a specialist for Urology at the University Hospital TUM Klinikum rechts der Isar in Munich.

Heck and his team collaborated with colleagues led by Dr. Christof Winter, a physician and bioinformatician and the head of the Liquid Profiling and Bioinformatics lab at the TUM Institute of Clinical Chemistry and Pathobiochemistry, to develop a new blood test. Until now, blood tests used to detect prostate tumor cells have looked for specific surface structures on the cells. Its not only a time-consuming and expensive process because of the special equipment required for the tests, but its also not always efficacious. If the cells being tested lack the specific structure being searched for, these tests fail to detect their presence. The new test developed by TUM researchers utilizes a completely different method in order to reliably, quickly and inexpensively measure the presence of the modified receptor AR-V7 at an early stage. Moreover, it can also determine whether or not the tumor is resistant to treatment with abiraterone and enzalutamide.

HIGH TESTING SENSITIVITY AND ACCURACY

The new blood test provides an alternative to existing models and potential to improve them: It analyzes the amount of AR-V7 RNA molecules in the blood. In each and every one of the cells in our body, RNA is responsible for the translation of genetic information into protein molecules, including receptor molecules. If the test detects high levels of AR-V7 RNA in the blood, it is likely that the patient already has tumor cells resistant to therapy with abiraterone and enzalutamide. Dr. Silvia Thne, co-lead author of the study, emphasizes the high sensitivity and accuracy of the new testing method: Only minute amounts of RNA are needed in a sample for the test to work. Additionally, since AR-V7 RNA is present in every tumor cell that possesses the resistant receptors, it means that no tumor cells are slipping by undetected.

For the study, TUM researchers analyzed blood samples from 85 patients with advanced stages of prostate cancer. They were able to successfully demonstrate that approximately one fifth of the patients had large amounts of AR-V7 RNA in their blood an indication of large quantities of resistant tumor cells. It was exactly these patients who failed to respond to therapy with abiraterone and enzalutamide. They also had poorer prognoses during the subsequent course of their illness: Their tumors returned more quickly and they had shorter survival times than other patients.

MORE WORK AHEAD

We were able to demonstrate that we can accurately predict whether or not resistance against abiraterone or enzalutamide is present in a patient, explains Winter. The next step for researchers will be to further improve upon the testing method and also compare its efficacy to that of existing testing methods using a larger sample of patients. The goal? TUM researchers want to determine if their new blood test can be incorporated into the routine battery of clinical examinations for prostate cancer patients in the future.

Reference

Seitz, A. K., Thoene, S., Bietenbeck, A., Nawroth, R., Tauber, R., Thalgott, M., ... & Ruland, J. (2017). AR-V7 in Peripheral Whole Blood of Patients with Castration-resistant Prostate Cancer: Association with Treatment-specific Outcome Under Abiraterone and Enzalutamide. European Urology.

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Blood Test Predicts Prostate Tumor Resistance - Technology Networks

Don't settle for being fat and strong. Here's why relative strength should be one of your goals.

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Filipino Express

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Side effects of brain radiation for small cell lung cancer - Testosterone enanthate and nandrolone decanoate cycle - Filipino Express

Although delayed ejaculation (DE) is typically characterized as a persistently longer than anticipated or desired time to ejaculation (or orgasm) during sexual activity, a timing-based definition of DE and its association with serum testosterone has not been established in a large cohort.

To examine in an observational study estimated intravaginal ejaculatory latency time (IELT) and masturbatory ejaculation latency time (MELT) in men self-reporting DE, assess the association of IELT and MELT withserum testosterone levels, and determine whether correlation with demographic and sexual parameters exist.

Men who resided in the United States, Canada, and Mexico were enrolled from 2011 to 2013. Self-estimated IELT and MELT were captured using an Ejaculatory Function Screening Questionnaire in a sample of 988 men screened for possible inclusion in a randomized clinical trial assessing testosterone replacement therapy for ejaculatory dysfunction (EjD) and who self-reported the presence or absence of DE and symptoms of hypogonadism. Additional comorbid EjDs (ie, anejaculation, perceived decrease in ejaculate volume, and decreased force of ejaculation) were recorded. Men with premature ejaculation were excluded from this analysis. IELT and MELT were compared between men self-reporting DE and men without DE. The associations of IELT and MELT with serum testosterone were measured.

IELT, MELT, and total testosterone levels.

Sixty-two percent of screened men self-reported DE with or without comorbid EjDs; 38% did not report DE but did report at least one of the other EjDs. Estimated median IELTs were 20.0 minutes for DE vs 15 minutes for no DE (P < .001). Estimated median MELTs were 15.0 minutes for DE vs 8.0 minutes for no DE (P < .001). Ejaculation time was not associated with serum testosterone levels. Younger men and those with less severe erectile dysfunction had longer IELTs and MELTs.

Estimated ejaculation times during vaginal intercourse and/or masturbation were not associated with serum testosterone levels in this study; thus, routine androgen evaluation is not indicated in these men.

This large systematic analysis attempted to objectively assess the ejaculation latency in men with self-reported DE. Limitations were that ejaculation time estimates were self-reported and were queried only once; the questionnaire did not distinguish between failure to achieve orgasm and ejaculation; and assessment of DE was limited to heterosexual vaginal intercourse and masturbation.

IELT and MELT were longer in men with DE, and there was no association of ejaculation times with serum testosterone levels in this study population. Morgentaler A, Polzer P, Althof S, etal. Delayed Ejaculation and Associated Complaints: Relationship to Ejaculation Times and Serum Testosterone Levels. J Sex Med 2017;XX:XXX-XXX.

The journal of sexual medicine. 2017 Aug 11 [Epub ahead of print]

Abraham Morgentaler, Paula Polzer, Stanley Althof, Alexander Bolyakov, Craig Donatucci, Xiao Ni, Ankur B Patel, Shehzad Basaria

Men's Health Boston, Chestnut Hill, MA, USA. Electronic address: ., Eli Lilly and Company, Indianapolis, IN, USA., Center for Marital and Sexual Health of South Florida, West Palm Beach, FL, USA., Weill Cornell Medical College, New York, NY, USA., Section on Men's Health, Aging and Metabolism, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.

PubMed http://www.ncbi.nlm.nih.gov/pubmed/28807505

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Delayed Ejaculation and Associated Complaints: Relationship to Ejaculation Times and Serum Testosterone Levels. - UroToday

Testosterone booster supplements

Testosterone is a male hormone. Hormones are chemical messengers that are secreted by the brain directly into the blood, which carries them to organs and tissues of the body to perform their functions. Testosterone is produced by the testicles, two oval organs that produce sperm in men. Dietary supplements help with increasing the levels of hormones if we have low levels in the body. In men, testosterone plays a key role in the development of male reproductive organs. In addition, it helps with increasing muscle mass, bone mass, and the growth of body hair. It is also good for general health and well-being. It also prevents loss of bone mass and density. Testosterone also helps maintain the sex drive and energy levels. Moreover, it helps with production of sperm and red blood cells. Testosterone levels start to fall with age. As a result, some men who have low testosterone levels may benefit from testosterone prescribed by their doctor. Testosterone booster supplements may also help.

The ingredients in testosterone supplements may be different. Some testosterone supplements contain zinc and magnesium. They increase testosterone levels in men who exercise. Some other testosterone supplements have hormones like DHEA (dehydroepiandrosterone) and pregnenolone. They help with making new testosterone and may help improve the ability to have an erection. But it doesn't seem to be helpful if the problem with erections is caused by diabetes or nerve disorders. Some testosterone booster supplements contain natural ingredients like herbs and botanicals. They may increase testosterone by increasing a hormone produced by the brain, which signals the testicles to produce more testosterone. In addition, others work by releasing bound testosterone, so it is in a form the body can use. Studies do not provide strong evidence that women benefit from taking these supplements. You need to talk to your doctor or pharmacist before starting a testosterone booster supplement. Discuss your medical history and current prescribed medications, over the counter medications, and any supplements that you are taking. Your doctor or pharmacist can tell you if a testosterone booster supplement is right for you. Once you know if a testosterone booster supplement is right for you, Walgreens has a variety of testosterone booster supplements to choose from and they come in different forms like tablets, capsules or gels.

This summary is intended for general informational purposes only, and should not be interpreted as specific medical advice. The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of purity, strength, or safety of the products. As a result, effects may vary. You should read product labels. In addition, if you are taking medications, herbs, or other supplements you should consult with a qualified healthcare provider before taking a supplement as supplements may interact with other medications, herbs, and nutritional products. If you have a medical condition, including if you are pregnant or nursing, you should speak to your physician before taking a supplement. Consult a healthcare provider if you experience side effects.

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Testosterone Supplements | Walgreens

Testosterone

Testosterone is a steroid hormone that acts in vertebrates to regulate many sexually dimorphic traits and express many fitness related traits in males (Zysline et al. 2006). A hormone is a secreted chemical messenger that coordinates cell-to-cell communication. Testosterone belongs to the class of steroid hormones known as androgensthe generic term for any natural or synthetic compound that stimulates or controls the development and maintenance of masculine characteristics in vertebrates by binding to androgen receptors, including the activity of the accessory male sex organs and development of male secondary sex characteristics.

Steroid hormones such as testosterone (and estradiol on the female side) act early in development to organize male or female phenotypes that are activated later (Zysline et al. 2006). Testosterone's chemical formula is C19H28O2.

Although testosterone in vertebrates can activate male-typical phenotypes, testosterone's presence and action is not limited to males, and both sexes of most vertebrate taxa naturally produce testosterone (Zysline et al. 2006; Nelson 2000). In mammals, including humans, testosterone is primarily synthesized in the male's testes, but small amounts are also secreted by the female ovaries, the placenta, and the adrenal glands of both sexes.

Scientists have isolated testosterone and developed procedures for utilizing it medically to treat a wide variety of medical and psychological conditions, including low libido and even depression. This represents one aspect of human creativityutilizing it in service to others. However, human creativity can also be applied toward ill purposes, and testosterone provides a good example. Despite known side effects, some have used testosterone and other steroids to gain unfair competitive advantage in sports. Some athletes have admitted winning competitions, such as track and field events while circumventing the rules with performance enhancing drugs, to the detriment of honest competitors. This case of sacrificing others and the sport for one's personal gain reveals an unethical application of human creativity.

Testosterone's effects can be classified as either anabolic (related to protein synthesis and growth) or virilizing (related to the biological development of male sex characteristics). However, the two categories are closely related:

Greatly differing amounts of testosterone prenatally, at puberty, and throughout life account for a share of biological differences between males and females. On average, the adult male human produces about 20 to 30 times the amount of testosterone synthesized by an adult female (Larsen, et al. 2002). Nonetheless, like men, women rely on testosterone (albeit in significantly smaller quantities) to maintain libido, bone density, and muscle mass throughout their lives.

Since testosterone was isolated by scientists in the 1930s, it has been used to treat a host of clinical issues, ranging from hypogonadism (the underproduction of natural testosterone) to certain forms of cancer, osteoporosis, and depression. More recently, testosterone replacement therapy has become available to older men, whose testosterone levels naturally decline with age; however, large-scale trials to assess the efficiency and long-term safety of this treatment are still lacking.

Anabolic steroids, a category which includes testosterone and its derivatives, have also received attention due to their controversial use to increase muscle mass and enhance athletic performance. Anabolic steroids were designated a controlled substance by the United States Congress in 1990, under the Anabolic Steroid Control Act; Canada, the United Kingdom, Australia, Argentina, and Brazil also have laws controlling their use and distribution (The Steroid Group, 2006).

Like other steroid hormones, testosterone is derived from cholesterol, a sterol lipid with the chemical formula C27H45OH. Steroids are characterized by a carbon skeleton with four fused rings; they are distinguished by the functional groups attached to the rings.

Androgens (such as testosterone) are a major class of steroid hormones responsible for the development of male secondary sex characteristics. Testosterone is derived from the androgen androstenedione via a reduction of its 17-keto group.

The presence of a hydroxyl group (-OH) at position C-17 has enabled the development of synthetic forms of testosterone that can be administered in therapeutic treatments:

Most hormones are synthesized in a specialized tissue, then released to target cells as needed. The largest amount of testosterone is produced by the testes in men, but it is also synthesized in smaller quantities in women by the thecal cells of the ovaries, the placenta, and the zona reticularis of the adrenal cortex in both sexes.

In the testes, testosterone is specifically produced by the Leydig cells. The male generative glands also contain the Sertoli cells, which require testosterone for spermatogenesis (the synthesis of spermatozoa).

Because testosterone is not soluble in water, it is transported to target cells bound to a specific plasma protein called sex hormone binding globulin (SHBG). When a hormone arrives at the target cell, it binds to, or fits, a site on the receptor protein. Binding creates a ligand-receptor complex, causing a conformational change (a change in the molecule's structural arrangement) that initiates a sequence of reactions leading to a change in cellular function.

The effects of testosterone in humans and other vertebrates are triggered via two main mechanisms: (1) by activation of the androgen receptor and (2) by conversion of testosterone to the steroid estradiol, the major estrogen in humans, which in turn activates certain estrogen receptors.

The rate of hormone biosynthesis and secretion is often regulated by feedback circuits, in which changes in the level of one hormone affects the levels of other hormones. Luteinizing hormone (LH), which is synthesized and secreted by the anterior lobe of the pituitary gland, functions in the regulation of testosterone levels. LH acts upon the Leydig cells of the testis to stimulate testosterone production. LH's release is controlled by pulses of gonadotropin-releasing hormone (GnRH) from the hypothalamus. These pulses, in turn, are subject to estrogen feedback from the gonads.

Testosterone has its greatest impact on sexual differentiation during two stages of life: (1) Before birth and (2) during puberty.

Most prenatal androgen effects in humans occur between the 7th and 12th weeks of gestation, and are responsible for the masculinization of the developing fetus. Changes include closure of the perineum, thinning and rugation of the scrotum, growth of the penis, and closure of the urethral groove to the tip of the penis.

Prenatal virilization of genetic females and undervirilization of genetic males are common causes of ambiguous genitalia and intersex conditions. Undervirilization can occur if a genetic male cannot produce enough androgen or the body tissues are unable to respond to it. In females, intrauterine exposure to heightened levels of testosterone leads to profound genital abnormalities. In humans, for example, excessive exposure to androgens in the womb gives a girl a greatly enlarged clitoris and a vagina that is partially fused shut. In the most severe form of congenital adrenal hyperplasia, complete masculinization of a genetically female fetus results in an apparently normal baby boy with no palpable testes. More often, the virilization is partial and the genitalia are ambiguous.

Postnatal effects in both males and females are mostly dependent on the levels and duration of circulating free testosterone.

Early postnatal effects are the first visible effects of rising androgen levels in childhood, and occur in both boys and girls during puberty. They include adult-type body odor, increased oiliness of skin (acne), appearance of pubic hair and underarm hair, growth spurts (accelerated bone maturation), and the appearance of fine upper lip and sideburn hair.

In males, the following advanced postnatal effects typically manifest themselves during late puberty:

Adult testosterone effects are more clearly demonstrable in males than in females, but are likely important to both sexes. Some of these effects may decline as testosterone levels decrease in the later decades of adult life. They include maintenance of muscle mass, maintenance of bone density, libido, and clitoral engorgement/penile erection frequency.

Behavioral effects of hormones are difficult to understand and to attribute to a given cause; in addition, a given hormone can have very different effects on behavior depending on the region of the central nervous system on which it acts. Nonetheless, high levels of circulating testosterone have been correlated to aggression in a variety of vertebrate species. For elephant bulls in musth (period condition in bull elephants), the amount of testosterone in the blood soars to levels fifty times higher than usual; during this period, male elephants demonstrate a mix of desperate lust and rage and are likely to engage in fights with other similarly affected males. Moreover, abnormal intrauterine exposure to androgens fosters aggression in females: Female mice that are snuggled between their brothers during fetal life are exposed to higher levels of androgens than females nestled between sisters and are more aggressive adults (Judson 2002).

The aggression associated with high levels of naturally circulating testosterone seems to be closely related to reproduction. For example, in male red-winged blackbirds (agelaius phoeniceus), testosterone levels peak during the two-week period when males are defending breeding territories and guarding their mates from rivals (Barnard 2003).

A experimental study on female dark-eyed juncos, a species of bird, found that exogenously increased testosterone levels led to increased intrasexual aggression (as well as decreased cell-mediated immune function) (Zysling et al. 2006). Increased aggressive behavior in female birds might help them acquire high quality mates or nesting sites, be more active in nest defense, or help win territorial interactions with other females, but might also lead to increased energy expenditure, potential for injury, or risk of predation (Zysling et al. 2006).

Various forms of exogenous (externally produced) testosterone and other anabolic steroids are used in medical treatment and (more controversially) as a bodybuilding tool or performance enhancer; they are most commonly administered in oral, injectable, and transdermal form.

Testosterone was originally used for the treatment of males who have little or no natural testosterone productionthat is, males with hypogonadism. Hormone replacement therapy maintains blood testosterone levels in the normal range.

Over the years, testosterone has been administered to treat a variety of conditions, including infertility, lack of libido or erectile dysfunction, osteoporosis, and for penile enlargement, height growth, bone marrow stimulation and reversal of anemia, and even appetite stimulation.

To take advantage of its virilizing effects, testosterone is often administered to female-to-male transsexual men as part of hormone replacement therapy, with a "target level" of the normal male testosterone level.

Decline of testosterone production with age has led to a demand for androgen replacement therapy, though there is disagreement within the medical community about the efficacy and safety of such treatments. Caution about embracing testosterone replacement therapy stems in part from the lessons of female hormone replacement therapy trials, where initially promising results were later refuted by larger studies. Still, testosterone replacement therapies in women to treat or prevent osteoporosis have yet to show the risks now associated with estrogen replacement therapies.

Women may use testosterone to treat low libido, often a symptom or outcome of hormonal contraceptive use. Women may also use testosterone therapies to treat or prevent loss of bone density and muscle mass and to treat certain kinds of depression.

Some drugs work to reduce testosterone's effects. For example, finasteride inhibits the conversion of testosterone into its metabolite dihydrotestosterone (DHT). By lowering levels of DHT, finasteride may be used to treat benign prostatic hyperplasia (BPH) and androgenetic alopecia (male-pattern baldness).

Testosterone administered to an athlete in order to improve performance is considered to be a form of doping in most sports. After a series of scandals and publicity in the 1980s (such as runner Ben Johnson's improved performance at the 1988 Summer Olympics), prohibitions of anabolic steroid use were renewed or strengthened by many sports organizations. Testosterone and other anabolic steroids were designated a controlled substance by the United States Congress in 1990.

Anabolic steroids have been associated with numerous side effects when administered in excessive doses; these include elevated cholesterol levels, acne, elevated blood pressure, hepatotoxicity, and alterations in left ventricle morphology. Adolescents who abuse anabolic steroids also risk stunted growth.

Some side effects are gender specific. Development of breast tissue in males, a condition called gynecomastia, is usually caused by high levels of circulating estrogen, the result of the increased conversion of testosterone to estrogen via an aromatase enzyme. Another male-specific side effect is testicular atrophy, a temporary reduction in the size of the testes. Possible female-specific side effects include increases in hair, deepening of the voice, enlarged clitoris (clitoral hypertrophy), as well as temporary decreases in menstrual cycles. When taken during pregnancy, anabolic steroids can affect fetal development.

A popular conception, perhaps misconception, regarding the side effects of anabolic steroids is that use leads to increased aggression, known in popular parlance as roid rage. Some early studies have shown a slight correlation between manic symptoms and anabolic steroid use; however, more comprehensive and recent studies have brought into question their methodology and conclusions (Pope and Katz 1988). Many scientists and medical professionals have concluded that anabolic steroids do not markedly increase aggressive behaviors (Fudala et al. 2003; Pope et al. 2000; OConner 2002).

All links retrieved November 20, 2015.

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Testosterone - New World Encyclopedia

Testosterone, hormone produced by the male testis that is responsible for development of the male sex organs and masculine characteristics, including facial hair and deepening of the voice. Testosterone was isolated from testicular extracts in 1935. Its discovery followed that of an androgen (male hormone) called androsterone, which was isolated from urine in 1931. However, testosterone proved to be more potent than androsterone, which was later shown to be a biochemical product (a metabolite) of testosterone.

A healthy man produces about 5 mg (1.8 104 ounces) of testosterone daily. Testosterone serves as a circulating prohormone for a more active androgen called dihydrotestosterone. Testosterone is converted to dihydrotestosterone in most tissues that are sensitive to androgens, including the testes, prostate gland, hair follicles, and muscles. Although testosterone itself has androgenic actions, its conversion to dihydrotestosterone is critical to the development of external genitalia in boys. Testosterone is also converted to estradiol in adipose tissue (and to a lesser extent in some other tissues), which is the most important source of estrogen in men. Furthermore, testosterone is interconvertible with androstenedione, which can be converted into estrogens. When androstenedione is formed in adipose tissue, it may be converted to a form of estrogen called estrone.

Similar to other steroid hormones, testosterone exists in serum in two forms. Most testosterone in the serum is bound to sex hormone-binding globulin and to albumin, while the remaining amount (about 1 percent) is free, or unbound. Free testosterone is in equilibrium with bound testosterone so that when free testosterone enters cells, some bound testosterone is immediately freed. In the cytoplasm of target cells, testosterone or dihydrotestosterone binds to specific androgen receptors, and the hormone-receptor complexes enter the cell nucleus, where they modulate protein synthesis by influencing the rate at which particular genes are transcribed (see transcription).

Testosterone has several major actions. It provides negative feedback inhibition on the secretion of gonadotropin-releasing hormone from the hypothalamus and the secretion of luteinizing hormone from the pituitary gland. It also directs the development of the embryonic Wolffian ducts into the vas deferens (ductus deferens) and seminal vesicles and stimulates the formation of muscle and bone. Dihydrotestosterone is responsible for sperm maturation during spermatogenesis, for the formation of the prostate gland and external genitalia, and for sexual maturation at puberty.

Testosterone can be manufactured by chemical and microbiological modification of inexpensive steroids, such as diosgenin. It is used clinically to treat testicular insufficiency, to suppress lactation (milk production), and to treat certain types of breast cancer.

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testosterone | hormone | Britannica.com

It's no secret financial tradershave always beenpredominately male.

So, when a group of researchers with the Ivey Business School at Western University in London, Ont., set out toat look at the role of testosterone on the markets, it wasn't a far-flung idea.

"We wanted to simulate what happens when people are at elevated levels ... how would they trade with high testosterone," saidIveyassistant finance professorand researcher AmosNadlerin an interview with CBC Radio's London Morning.

For their "experimental market" study, researchers divided 140 men into two groups and let them do mock trading amongstthemselves. One group received a placebo treatment the other, a topical gel containing testosterone.

Amos Nadler is an assistant finance professor with the Ivey Business School at Western University. He was involved in the study on financial trading and testosterone. (Courtesy: Ivey School of Business, Western University)

The result? The testosterone-fuelled group was more reckless in its trading, willing to bid well above the value of a given commodity in hopes of a higher return. Researchers say the behaviour increased the odds of a market crash.

By comparison, the placebo group was trading more rationally, buying low to sell high, instead of buying high to sell higher.

"Your body produces more testosterone when you prepared for a challenge ... even more testosterone when you are winning," said Nadler.

When the financial crash hit Wall Street a decade ago, a funny thing happened. Male financial executives started turning to doctors for testosterone supplements in hopes it would boost their output and sharpen their faculties.

"All of these men are under tonnes of stress, and stress will reduce their levels of testosterone," said Manhattan-based Dr. LionelBissoonin a story in the Financial Times in 2012

Nadler said studies based on gender rather than the male hormone found that women also tend to keep a more level head in the high-adrenalin setting of a trading floor.

"Single males over-traded and lost the most money, while women tend to be more conservative and actually make more money than men," said Nadler

The Ivey study was done in collaboration with the University of Oxford and Claremont Graduate University in Claremont, Calif.

While it found that testosterone clearly played a role in more reckless trading and spending, Nadler cautions male traders aren't all bad.

"Being slightly more impulsive can be a good thing ... there are some results that showed the higher-testosterone guys made a bit more money than their counterparts," said Nadler.

"It can also be very harmful in some situations if you are being impulsive."

The research paper, titledThe Bull of Wall Street: Experimental Analysis of Testosterone and Asset Trading, will appear in an upcoming issue ofthe publication, Management Science.

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Elevated testosterone linked to 'reckless' financial trading, study ... - CBC.ca

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