Testosterone Wikipedia

Immunofluorescence assays exhibit considerable variability in quantifying testosterone concentrations in blood samples due to the cross-reaction of structurally similar steroids, leading to overestimating the results. In measurements of testosterone in blood samples, different assay techniques can yield different results. Several professional medical groups have recommended that 350 ng/dL generally be considered the minimum normal level, which is consistent with previous findings.non-primary source neededmedical citation needed Levels of testosterone in men decline with age.
A small portion of approximately 3% of testosterone is reversibly converted in the liver into androstenedione by 17β-HSD. In the hepatic 17-ketosteroid pathway of testosterone metabolism, testosterone is converted in the liver by 5α-reductase and 5β-reductase into 5α-DHT and the inactive 5β-DHT, respectively. The conjugates of testosterone and its hepatic metabolites are released from the liver into circulation and excreted in the urine and bile. Androsterone and etiocholanolone are then glucuronidated and to a lesser extent sulfated similarly to testosterone.
Testosterone and the classical nuclear androgen receptor first appeared in gnathostomes (jawed vertebrates). They named the hormone testosterone, from the stems of testicle and sterol, and the suffix of ketone. Suffering  clenbuterol kopen nederland forum  of his colleagues, he abandoned his work on the mechanisms and effects of androgens in human beings. A testicular action was linked to circulating blood fractions – now understood to be a family of androgenic hormones – in the early work on castration and testicular transplantation in fowl by Arnold Adolph Berthold (1803–1861).
nhand  does not appear to increase the risk of developing prostate cancer. Prenatal androgens apparently influence interests and engagement in gendered activities and have moderate effects on spatial abilities. Specifically, testosterone, along with anti-Müllerian hormone (AMH) promote growth of the Wolffian duct and degeneration of the Müllerian duct respectively. Testosterone can be described as having anabolic and androgenic (virilising) effects, though these categorical descriptions are somewhat arbitrary, as there is a great deal of mutual overlap between them. In addition to its role as a natural hormone, testosterone is used as a medication to treat hypogonadism and breast cancer. Like other androsteroids, testosterone is manufactured industrially from microbial fermentation of plant cholesterol (e.g., from soybean oil).
In non-human primates, it may be that testosterone in puberty stimulates sexual arousal, which allows the primate to increasingly seek out sexual experiences with females and thus creates a sexual preference for females. The reflexive testosterone increases in male mice is related to the male's initial level of sexual arousal. When testosterone-deprived rats were given medium levels of testosterone, their sexual behaviours (copulation, partner preference, etc.) resumed, but not when given low amounts of the same hormone.
In women with hyperandrogenism, mean levels of total testosterone have been reported to be 62.1 ng/dL. Total levels of testosterone in the body have been reported as 264 to 916 ng/dL (nanograms per deciliter) in non-obese European and American men age 19 to 39 years, while mean testosterone levels in adult men have been reported as 630 ng/dL. It is bound 65% to sex hormone-binding globulin (SHBG) and 33% bound weakly to albumin. When testosterone levels are low, gonadotropin-releasing hormone (GnRH) is released by the hypothalamus, which in turn stimulates the pituitary gland to release FSH and LH.
5α-DHT binds to the same androgen receptor even more strongly than testosterone, so that its androgenic potency is about 5 times that of T. Free testosterone (T) is transported into the cytoplasm of target tissue cells, where it can bind to the androgen receptor, or can be reduced to 5α-dihydrotestosterone (5α-DHT) by the cytoplasmic enzyme 5α-reductase. Androgens such as testosterone have also been found to bind to and activate membrane androgen receptors. The relationship between sex steroids and SHBG in physiological and pathological conditions is complex, as various factors may influence the levels of plasma SHBG, affecting bioavailability of testosterone. Only the free amount of testosterone can bind to an androgenic receptor, which means it has biological activity.
Men who produce less testosterone are more likely to be in a relationship or married, and men who produce more testosterone are more likely to divorce. However, the testosterone changes observed do not seem to be maintained as relationships develop over time. Testosterone may be a treatment for postmenopausal women as long as they are effectively estrogenized. Women's level of testosterone is higher when measured pre-intercourse vs. pre-cuddling, as well as post-intercourse vs. post-cuddling. This reaction engages penile reflexes (such as erection and ejaculation) that aid in sperm competition when more than one male is present in mating encounters, allowing for more production of successful sperm and a higher chance of reproduction.
goldfieldstvet  found that administering testosterone increased verbal aggression in some participants. In one experiment, subjects who interacted with handguns showed higher testosterone levels and aggression than those who interacted with toys. The rise in testosterone during competition predicted aggression in males, but not in females. Higher testosterone levels in men reduce the risk of becoming or staying unemployed. Physical presence may be required for women who are in relationships for the testosterone–partner interaction, where same-city partnered women have lower testosterone levels than long-distance partnered women.