There's more to testosterone than guys behaving badly. When you think of testosterone, what comes to mind? Can men hold off on treating recurring prostate cancer? Cited by other articles As surprising as it may be, women can also be bothered by symptoms of testosterone deficiency. Also, as men get older, their livers make more sex hormone binding globulin (SHBG), which binds to testosterone circulating in the bloodstream. Women with high testosterone levels, due to either disease or drug use, may experience a decrease in breast size and deepening of the voice, in addition to many of the problems men may have. One treatment available for many of these problems is spironolactone, a special type of diuretic (water pill) that blocks the action of male sex hormones. This is an open access article distributed under the terms of the Creative Commons Attribution License CC-BY 4.0., which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Stay on top of latest health news from Harvard Medical School. 25 Gut Health Hacks is yours absolutely FREE when you sign up to receive health information from Harvard Medical School. Get the latest in health news delivered to your inbox! However, the optimal amount of testosterone is far from clear. Testosterone is also metabolized to dihydrotestosterone—a potent, non-aromatizable AR agonist—through steroid 5α-reductases. In female adults, high levels of testosterone may be a sign of polycystic ovary syndrome (PCOS). High levels of testosterone in female infants may lead to enlargement of their clitoris that can look almost like a penis. Excess testosterone in male children can lead to precocious (early) puberty, which is when puberty begins before the age of nine. Professional development Libido, or sexual desire, is significantly influenced by testosterone, which regulates various brain regions involved in sexual motivation, including the hypothalamus; in men, testosterone plays a crucial role in sexual desire and arousal . The enzyme aromatase in men can aromatize testosterone into estrogen, which affects a variety of physiological processes, such as bone health and reproductive capabilities; the average testosterone level in healthy men is between 264 and 916 ng/dL . The production of testosterone in men is primarily controlled by negative feedback mechanisms, whereby high levels of testosterone prevent the release of GnRH from the hypothalamus and LH from the pituitary, thereby limiting further testosterone synthesis; testosterone is made from cholesterol by a variety of enzymatic pathways in the testes . Testosterone is converted to dihydrotestosterone in most tissues that are sensitive to androgens, including the testes, prostate gland, hair follicles, and muscles. 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. It’s natural for testosterone levels to vary depending on your age and overall health. It affects male fetuses as they develop in the uterus, as well as teenage sexual development during puberty. Testosterone is a hormone that your gonads (sex organs) mainly produce.Additionally, it aims to clarify the effects of testosterone dysregulation on men's mental and physical wellness while advancing clinical procedures and treatment approaches.Here, we highlight key milestones in the history of testosterone’s discovery and therapeutic applications.Considering the prospective benefits of testosterone therapy, more investigation and clinical testing are necessary to completely comprehend its effects and improve therapeutic modalities.In men, testosterone is primarily synthesized in the testes and the adrenal gland, with smaller amounts produced in the ovaries and adrenal glands in women .However, the optimal amount of testosterone is far from clear.Testosterone is essential for the production of sperm. In men, the endocrine system, which includes glands like the pituitary, thyroid, adrenal, and gonads, releases hormones that control important functions like growth, metabolism, reproduction, and mood . A key component of human physiology is hormonal regulation, which intricately regulates a wide range of biological processes and maintains homeostasis across multiple systems; from the many hormones that regulate bodily functions, testosterone stands out for its significant and complex effects on male health . Testosterone therapy has modest advantages, especially for men who have hypogonadism symptoms and low testosterone levels. Testosterone supplements can have a good impact on a number of important aspects of men's health, such as vascular endothelial function, mood (particularly in lowering depression), muscle strength, bone health, and sexual function. For men with low blood testosterone levels and symptoms most likely caused by a low level, the benefits of hormone replacement therapy usually outweigh potential risks. Part of this may be due to the difficulty defining "normal" testosterone levels and "normal" behavior. While the specifics are uncertain, it's possible that androgens also play an important role in normal brain function (including mood, sex drive and cognitive function). It's one of several androgens (male sex hormones) in females. The pituitary gland then relays signals to the testes to produce testosterone. It is essential to the development of male growth and masculine characteristics. About Nature Portfolio Late-onset male hypogonadism happens when the decline in testosterone levels is linked to general aging and/or age-related conditions, particularly obesity and Type 2 diabetes. Lower-than-normal testosterone levels typically only cause symptoms in males. If any of these organs — your hypothalamus, pituitary gland or gonads — aren’t working normally, that can cause abnormal testosterone levels. Moreover, by encouraging the synthesis of nitric oxide, aiding in the development and repair of endothelial cells, and lowering inflammation, testosterone improves endothelial function, which is essential for preserving vascular health and underscoring testosterone's complex role in general physiological well-being . What happens when testosterone levels are too low? Additionally, testosterone plays a vital role in vascular health by improving endothelial function, which is crucial for maintaining cardiovascular health in men. Currently, there are various approaches to treating patients with testosterone insufficiency, including the use of testosterone pellets and formulations combined with aromatase inhibitors, which need more studies for a better understanding of their effects . Furthermore, via binding to androgen receptors in muscle cells, testosterone stimulates protein synthesis and muscular growth, which is crucial for the regulation of muscle mass . Because it promotes protein synthesis and muscle hypertrophy through androgen receptor binding in muscle cells, testosterone is a critical regulator of muscle mass; this anabolic impact is required for muscle development and repair, making testosterone crucial for preserving muscle mass . Regarding mental health, testosterone may help certain people with their depression symptoms; this is especially important for patients with hypogonadism, such as elderly people, for whom testosterone replacement therapy may be quite beneficial . Our understanding of the relative advantages of both physiological and pharmacological therapies for aging men is greatly improved by the effects of testosterone treatment and exercise on factors such as strength, aerobic fitness, and body composition . Additionally, there is a significant correlation between bone density and testosterone levels; a decrease in testosterone can result in decreased bone density . In men with hypogonadism, including elderly individuals, testosterone replacement therapy may offer antidepressant effects, providing therapeutic benefits for those with testosterone deficiency . nature.com sitemap If testosterone levels are too high or too low, it can cause certain symptoms. Long recognized for its role as a sex hormone, mounting evidence underscores the importance of testosterone in the regulation of systemic metabolism in both male and female organisms. In both men and women, testosterone functions directly through the androgen receptor (AR) and indirectly as a prohormone, converted by aromatase into 17β-oestradiol (oestradiol), which activates the oestrogen receptors ERα and ERβ. At around week seven in utero, the sex-related gene on the Y chromosome initiates the development of the testicles in male infants. Synthetic testosterone is the main drug of masculinizing hormone therapy. "Anabolic" refers to muscle building, and "androgenic" refers to increased male sex characteristics. It’s unlikely — and difficult to tell — that a male adult has higher-than-normal levels of testosterone. It’s important to note that the normal ranges for testosterone levels can vary based on the type of blood test done and the laboratory where it is done. The two charts below list the general normal ranges of testosterone based on age and sex. Men taking testosterone replacement must be carefully monitored for prostate cancer. Testosterone may stimulate the prostate gland and prostate cancer to grow. Affected women may experience low libido, reduced bone strength, poor concentration or depression. For example, a man with osteoporosis and low testosterone can increase bone strength and reduce his fracture risk with testosterone replacement. Some men who have a testosterone deficiency have symptoms or conditions related to their low testosterone that will improve when they take testosterone replacement. Testosterone, a steroid hormone predominantly synthesized in the testes, is integral to a wide range of physiological processes that are crucial to male health; the regulation of testosterone levels operates through a feedback mechanism that is essential for understanding its physiological control.It is used clinically to treat testicular insufficiency, to suppress lactation (milk production), and to treat certain types of breast cancer.Its discovery followed that of an androgen (male hormone) called androsterone, which was isolated from urine in 1931.Natural testosterone is a steroid — an anabolic-androgenic steroid.Seven studies were eventually included in the systematic review (Table 1), and all of them showed beneficial impacts on a range of health outcomes, including depression, vascular endothelial function, muscle strength, bone health, and sexual function.Testosterone deficiency during fetal development doesn’t allow male characteristics to develop normally.Among women, perhaps the most common cause of a high testosterone level is polycystic ovary syndrome (PCOS).Additionally, testosterone supports endothelial function by increasing nitric oxide production, encouraging endothelial cell growth and repair, and lowering inflammation; it also has a significant impact on the vascular endothelium, the thin layer of cells lining blood vessels, which is essential for preserving cardiovascular health .However, the wisdom and effectiveness of testosterone treatment to improve sexual function or cognitive function among postmenopausal women is unclear.Testosterone is an essential part of reproductive health. Testosterone deficiency during fetal development doesn’t allow male characteristics to develop normally. This condition is very common — up to 15% of females of reproductive age have it. LH then travels to your gonads and stimulates the production and release of testosterone. For adult females, testosterone enhances libido. The Leydig cells of the testes are the main source of testosterone in men; although testosterone is frequently regarded as a male hormone, it is essential for many physiological processes outside of sexual differentiation, including maintaining muscle mass, bone density, mood regulation, and metabolic processes . Conclusively, testosterone is an essential hormone that is involved in many physiological processes throughout men's lives; in addition to controlling libido, testosterone is closely linked to bone density, muscle growth, and repair; its influence on mental health, especially in reducing symptoms of depression, emphasizes its complex nature. Seven studies were eventually included in the systematic review (Table 1), and all of them showed beneficial impacts on a range of health outcomes, including depression, vascular endothelial function, muscle strength, bone health, and sexual function. Descriptive, observational, and experimental studies including healthy men-more especially, those assessing the effects of testosterone therapy-were required for inclusion. Beyond these physical advantages, testosterone plays a crucial role in male reproductive health by affecting spermatogenesis (the generation of sperm), libido, and erectile function. However, the wisdom and effectiveness of testosterone treatment to improve sexual function or cognitive function among postmenopausal women is unclear. Blood levels of testosterone vary dramatically over time and even during the course of a day. These hormones are thought to have important effects on There may be other important functions of this hormone that have not yet been discovered. For example, did you know that testosterone is a key player in prostate cancer? For example, a man with osteoporosis and low testosterone can increase bone strength and reduce his fracture risk with testosterone replacement.The increase in sex steroid production during puberty speeds up bone mineral accumulation and causes sex-specific variations in bone growth; after mid-puberty, the male population experiences a greater increase in periosteal bone growth than the female population, who shows more pronounced endocortical bone formation .Free testosterone is in equilibrium with bound testosterone so that when free testosterone enters cells, some bound testosterone is immediately freed.Some men and women experience immediate side effects of testosterone treatment, such as acne, disturbed breathing while sleeping, breast swelling or tenderness, or swelling in the ankles.As a result, there is some controversy about which men should be treated with supplemental testosterone. Similar articles In fact, as men age, testosterone levels drop very gradually, about 1% to 2% each year — unlike the relatively rapid drop in estrogen that causes menopause. Signals sent from the brain to the pituitary gland at the base of the brain control the production of testosterone in men. Excess testosterone affects your body differently depending on your sex and age. If you thought testosterone was only important in men, you'd be mistaken. For example, the genitals may not enlarge, facial and body hair may be scant, and the voice may not deepen normally. Adolescent boys with too little testosterone may not experience normal masculinization. A "feedback loop" closely regulates the amount of hormone in the blood. They travel from one organ or another place in the body, usually through the bloodstream, and affect many different bodily processes. As testosterone in your blood increases, it suppresses the production of gonadotropin-releasing hormone, which helps maintain normal levels of testosterone. However, the majority of testosterone produced in the ovaries is converted to the primary female sex hormone, estradiol. Your adrenal glands also produce the hormone dehydroepiandrosterone (DHEA), which your body transforms into testosterone and estrogen. Testosterone therapy may make sense for women who have low testosterone levels and symptoms that might be due to testosterone deficiency. Testosterone therapy is approved for the treatment of delayed male puberty and abnormally low production of testosterone secondary to malfunction of the testes, pituitary or hypothalamus. Additionally, testosterone supports endothelial function by increasing nitric oxide production, encouraging endothelial cell growth and repair, and lowering inflammation; it also has a significant impact on the vascular endothelium, the thin layer of cells lining blood vessels, which is essential for preserving cardiovascular health . It has been demonstrated that testosterone replacement treatment (TRT) improves muscle mass, strength, and physical function in hypogonadal men, while research indicates that men with low testosterone levels have decreased muscle mass and strength . Essential for bone maturation, testosterone helps bones reach maximal mass and preserves bone density, all during adulthood; it also promotes skeletal growth by improving mechanical loading . The brain's hypothalamus starts the hormonal cascade by secreting gonadotropin-releasing hormone (GnRH), which causes the pituitary gland to release follicle-stimulating hormone (FSH) and luteinizing hormone (LH) . The hypothalamic-pituitary-gonadal (HPG) axis, a crucial part of the endocrine system, controls the production of testosterone. In men, testosterone is primarily synthesized in the testes and the adrenal gland, with smaller amounts produced in the ovaries and adrenal glands in women . 25 Gut Health Hacks is yours absolutely FREE when you sign up to receive health information from Harvard Medical School.While the specifics are uncertain, it's possible that androgens also play an important role in normal brain function (including mood, sex drive and cognitive function).The testes produces less testosterone, there are fewer signals from the pituitary telling the testes to make testosterone.Levels of testosterone are naturally much higher in males.Additionally, testosterone plays a vital role in vascular health by improving endothelial function, which is crucial for maintaining cardiovascular health in men.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 triggers the development of the male internal and external reproductive organs during fetal development.Testosterone levels are naturally much higher in males. Testosterone levels are too carefully controlled by the brain for that to occur. But having high cholesterol doesn't mean your testosterone will be high. Testosterone is synthesized in the body from cholesterol. The proper balance between testosterone (along with other androgens) and estrogen is important for the ovaries to work normally. Testosterone is produced in the ovaries and adrenal gland. If you think you may have symptoms of low testosterone or excess testosterone, talk to your healthcare provider. Testosterone levels in males naturally decline with age. This is called androgen insensitivity syndrome (AIS) and occurs when someone is genetically male but is insensitive to androgens (male sex hormones). The symptoms of low testosterone vary based on your age. Your hypothalamus releases gonadotropin-releasing hormone (GnRH), which triggers your pituitary gland to release luteinizing hormone (LH). Your hypothalamus and pituitary gland control the amount of testosterone your gonads (testicles or ovaries) produce and release. Your body controls the levels of testosterone in your blood. Based on the predetermined criteria, publications that evaluated the effects of testosterone using descriptive, observational, or experimental designs involving human subjects were included. It involves dynamic interactions between the gonads, pituitary gland, and hypothalamus. Additionally, it aims to clarify the effects of testosterone dysregulation on men's mental and physical wellness while advancing clinical procedures and treatment approaches. Checking testosterone levels is as easy as having a blood test. Men and women need the proper amount of testosterone to develop and function normally. Because prostate cancer is so common, doctors tend to be leery of prescribing testosterone to men who may be at higher than average risk of having undiagnosed prostate cancer. These advantages include better vascular function, mood, muscle strength, bone density, and sexual health in healthy men. Classical male hypogonadism is when low testosterone levels are due to an underlying medical condition or damage to your testicles, pituitary gland or hypothalamus. The synthesis and regulation of testosterone, a vital steroid hormone, are highly complicated procedures that involve intricate interactions among multiple endocrine glands, including the hypothalamus, pituitary gland, and gonads, as well as feedback mechanisms that maintain homeostasis within the body. Testosterone, a steroid hormone predominantly synthesized in the testes, is integral to a wide range of physiological processes that are crucial to male health; the regulation of testosterone levels operates through a feedback mechanism that is essential for understanding its physiological control. It is used clinically to treat testicular insufficiency, to suppress lactation (milk production), and to treat certain types of breast cancer. Free testosterone is in equilibrium with bound testosterone so that when free testosterone enters cells, some bound testosterone is immediately freed. Furthermore, testosterone is interconvertible with androstenedione, which can be converted into estrogens. The objective of this systematic review is to critically analyze the various functions of testosterone, including its physiological importance, regulatory processes, and possible repercussions if it is dysregulated in men. Further research will better define the function of testosterone in both healthy and deficient men, which will eventually result in more accurate and successful treatment plans. Considering the prospective benefits of testosterone therapy, more investigation and clinical testing are necessary to completely comprehend its effects and improve therapeutic modalities. The goal of this study is to learn more about the critical and varied roles that testosterone plays in healthy men's physiological functioning. It's best to measure free testosterone levels in the morning. Small sample sizes and a dearth of studies, however, limit these findings, highlighting the need for more investigation to completely comprehend the wider impacts of testosterone on men's health. It has an effect on many body systems, underscoring its importance for men's physical health and fertility. Even with an abnormally low level that is replicated on a repeat test, the decision to begin testosterone replacement therapy and the proper dose requires a careful conversation with your doctor. Although testosterone may make prostate cancer grow, it is not clear that testosterone treatment actually causes cancer. Testosterone triggers the development of the male internal and external reproductive organs during fetal development. Healthcare providers use synthetic testosterone to treat and manage various medical conditions. Levels of testosterone are naturally much higher in males. Testosterone is the main androgen, meaning it stimulates the development of male characteristics. However, testosterone proved to be more potent than androsterone, which was later shown to be a biochemical product (a metabolite) of testosterone. If they’re consistently high or low, you may experience unpleasant symptoms worth discussing with your provider. Testosterone is an essential part of reproductive health. AIS prevents male genitals from developing as they should and almost always results in infertility (it’s difficult or impossible to father children) during adulthood. Late-onset hypogonadism affects about 2% of men over the age of 40. This is called androgen insensitivity syndrome (AIS) and occurs when someone is genetically male but is insensitive to androgens (male sex hormones).Adolescent boys with too little testosterone may not experience normal masculinization.Testosterone is synthesized in the body from cholesterol.They travel from one organ or another place in the body, usually through the bloodstream, and affect many different bodily processes.Get the latest in health news delivered to your inbox!The hypothalamic-pituitary-gonadal (HPG) axis, a crucial part of the endocrine system, controls the production of testosterone.Essential for bone maturation, testosterone helps bones reach maximal mass and preserves bone density, all during adulthood; it also promotes skeletal growth by improving mechanical loading . As a result, there is some controversy about which men should be treated with supplemental testosterone. The most common example is probably prostate cancer. There are times when low testosterone is not such a bad thing. The ovaries of women with PCOS contain multiple cysts. Having too much naturally-occurring testosterone is not a common problem among men. Estrogen therapy increases sex hormone binding globulin and, like aging men, this reduces the amount of free, active testosterone in the body. For example, problem with function of pituitary gland or adrenal glands may lead to reduced testosterone production. When testosterone levels rise too high, the brain sends signals to the pituitary to reduce production. Dihydrotestosterone is responsible for sperm maturation during spermatogenesis, for the formation of the prostate gland and external genitalia, and for sexual maturation at puberty. The likelihood of sarcopenia (age-related muscle loss) and diminished muscle strength rises as testosterone levels naturally fall with age; however, research indicates that testosterone therapy may mitigate these effects in older men, enhancing physical performance, sexual drive, and muscle mass . In addition to having significant effects on health and illness, these hormonal changes are necessary for preserving physiological balance; one particularly significant time of hormonal change is during puberty, when a rise in sex hormones, such as testosterone, promotes the growth of secondary sexual traits like increased muscle mass, body and facial hair, and a deeper voice . The research paper provides a thorough summary of the selection criteria and covers testosterone's effects on depression, vascular endothelium, muscle strength, bone health, and sexual function (Figure 1). A higher level of evidence would be provided by a well-conducted RCT, improving the consistency and dependability of the results and providing a more thorough knowledge of the effects seen across studies, so we could find more evidence in the future. A further 239 records were subsequently removed during the full-text screening stage; seven articles were, thus, left for an in-depth examination. Dysregulation of this feedback mechanism can lead to a variety of pathophysiological conditions, particularly testosterone deficiency; such disruptions may occur due to aging, disease processes, or lifestyle factors, underscoring the importance of accurate diagnosis and appropriate therapeutic interventions . Human development involves hormonal changes that start in fetal life and last into adulthood. An outline of the major hormonal changes that take place in men throughout their lives is given in this introduction, with special attention to testosterone's crucial role in controlling a wide range of physiological processes. About this article Testosterone is the major sex hormone in males. Learn all about the sex hormone here, including its primary benefits. 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. 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. 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. Similar to other steroid hormones, testosterone exists in serum in two forms.Testosterone therapy does not appear to increase the risk of prostate cancer, but it can stimulate the growth of prostate cancer cells.Your hypothalamus and pituitary gland control the amount of testosterone your gonads (testicles or ovaries) produce and release.Additionally, we synthesize the current understanding of testosterone as a key messenger promoting metabolic homeostasis in preclinical models and humans.Classical male hypogonadism is when low testosterone levels are due to an underlying medical condition or damage to your testicles, pituitary gland or hypothalamus.Testosterone serves as a circulating prohormone for a more active androgen called dihydrotestosterone.However, many men with normal testosterone levels have similar symptoms, so a direct connection between testosterone levels and symptoms is not always clear.The enzyme aromatase in men can aromatize testosterone into estrogen, which affects a variety of physiological processes, such as bone health and reproductive capabilities; the average testosterone level in healthy men is between 264 and 916 ng/dL . What's more, testosterone plays other important roles in health and disease that may surprise you. Similar to other steroid hormones, testosterone exists in serum in two forms. Although testosterone itself has androgenic actions, its conversion to dihydrotestosterone is critical to the development of external genitalia in boys. Testosterone serves as a circulating prohormone for a more active androgen called dihydrotestosterone. Its discovery followed that of an androgen (male hormone) called androsterone, which was isolated from urine in 1931. The increase in sex steroid production during puberty speeds up bone mineral accumulation and causes sex-specific variations in bone growth; after mid-puberty, the male population experiences a greater increase in periosteal bone growth than the female population, who shows more pronounced endocortical bone formation . As a primary hormone influencing bone metabolism, testosterone directly affects osteoclasts, osteoblasts, and osteocytes, promoting periosteal bone formation during puberty and decreasing bone resorption during adulthood; testosterone is also strongly correlated with bone density; lower testosterone levels result in decreased bone density . DHT has a stronger androgenic effect and is essential for the maintenance of prostate health and the development of secondary sexual traits in men . Specifically, when testosterone levels rise, the body reduces the production of its primary source, while a decline in testosterone levels prompts an increase in its production; this intricate feedback loop plays a critical role in maintaining hormonal balance and is essential for understanding the regulatory mechanisms governing testosterone in men . Testosterone is a hormone that your gonads (testicles or ovaries) mainly produce. Additionally, we synthesize the current understanding of testosterone as a key messenger promoting metabolic homeostasis in preclinical models and humans. Here, we highlight key milestones in the history of testosterone’s discovery and therapeutic applications. Testosterone therapy does not appear to increase the risk of prostate cancer, but it can stimulate the growth of prostate cancer cells. Some men and women experience immediate side effects of testosterone treatment, such as acne, disturbed breathing while sleeping, breast swelling or tenderness, or swelling in the ankles. Women may have a testosterone deficiency due to diseases of the pituitary, hypothalamus or adrenal glands, in addition to removal of the ovaries. Testosterone is a hormone that your gonads (sex organs) mainly produce. Testosterone levels are naturally much higher in males. Testosterone, discovered during the endocrine gold rush of the 1930s, was the first hormone chemically synthesized for replacement therapy. By identifying limitations in existing studies and suggesting directions for future investigations, we hope to encourage the research community to pursue more robust and methodologically sound studies that will further strengthen the evidence base. It is also critical to comprehend how the Free Androgen Index (FAI), which is connected with bone density, is used; a low FAI indicates a higher likelihood of bone density loss . It can also lead to precocious (early) puberty, which is when puberty begins before the age of eight. (LH more often stimulates the production of estrogen and progesterone in ovaries.) Testosterone is essential for the production of sperm. Natural testosterone is a steroid — an anabolic-androgenic steroid. More specifically, both testicles and ovaries produce testosterone. The development and maintenance of muscular mass, bone density, and general physical strength depend heavily on testosterone, a hormone that plays a complicated and significant role in men's physiology. However, many men with normal testosterone levels have similar symptoms, so a direct connection between testosterone levels and symptoms is not always clear. That's why medications that lower testosterone levels (for example, leuprolide) are common treatments for men with prostate cancer. All of this reduces the active (free) form of testosterone in the body. The testes produces less testosterone, there are fewer signals from the pituitary telling the testes to make testosterone. In recent years, researchers (and pharmaceutical companies) have focused on the effects of testosterone deficiency, especially among men. Among women, perhaps the most common cause of a high testosterone level is polycystic ovary syndrome (PCOS). In addition, what may seem like a symptom of testosterone excess (see below) may actually be unrelated to this hormone.