Testosterone Wiki Page

 

Testosterone is a steroid hormone from the androgen group. It is present in both men and women as well as in other vertebrates. Testosterone is responsible for physical changes in men during puberty, including deepening of the voice, growth of the penis, testes, muscles, facial, pubic and body hair, getting taller, and the production of sperm to be able to have children.[1] In addition, testosterone plays a great role in fat distribution, red blood cell production and maintaining bone density.[2]

In women, testosterone is present in smaller amounts. It functions to maintain sex drive, keep bones healthy, manage pain levels, and preserve cognitive health.[3] Also, it gives women a sense of motivation, assertiveness, and a feeling of well-being.

In men, the brain and pituitary gland (small gland at the base of the brain) control testosterone production by the testes.[4] From there, it moves through the blood to do its work. In women, testosterone is produced in various locations. One quarter of testosterone is produced in the ovaries, a quarter is produced in the adrenal glands, and one half is produced in the peripheral tissues from the various precursors in the ovaries and adrenal glands.[5]

Testosterone in Men

The levels of testosterone change from hour to hour and vary from person to person. They tend to be highest in the morning (that’s why early morning erections are common) and lowest at night. In general, the normal testosterone levels in males ranges from 270 to 1,070 ng/dL.[6] From the age of 30 onward, total testosterone levels in men decrease by 1% per year.[7]

Testosterone in Women

The production rate of testosterone in normal female is 0.2 to 0.3 mg/day.[8] Normal blood testosterone levels in females can range from 30 to 95 nanograms per deciliter (ng/dL).[9] The testosterone level in women is highest around age 20 and slowly declines until it is half as high in their 40s.[10] For those who had their ovaries removed, testosterone production significantly drops by half, sometimes resulting in less than the normal blood testosterone levels.  

Testosterone Replacement Therapy

The promise of testosterone therapy in both men and women may seem enticing, but there are a lot of misconceptions about what the treatment can and can’t do. Millions of American men rely on testosterone therapy to restore normal levels of the hormone and to help them feel more alert, young, energetic, sexually functional, mentally sharp, and feel good about themselves. However, legitimate safety concerns linger. For those who want to undergo testosterone replacement therapy, it is recommended to consult with a qualified and experienced physician first for further medical assessment and evaluation.

 

Andropause

Testosterone levels generally peak during the adolescent period and early adulthood. As men age and when they reach andropause or sometimes called male menopause (usually between the ages of 40 and 80), they can experience a number of symptoms related to natural decline in testosterone levels.[11]  

One of the most common symptoms is a decrease in sexual function. They experience reduced sex drive, fewer erections, hot flashes, and infertility. Other physical changes related to low testosterone levels include increased body fat, decreased muscle mass and body hair, fragile bones, swelling or tenderness in the breast tissue, increased fatigue, and disordered cholesterol metabolism.[12]

Despite the fact that low testosterone can cause decreased energy levels, it can also cause insomnia and changes in sleep patterns. The affected individual can also experience emotional changes such as feelings of sadness or depression, low self-esteem and motivation, lack of concentration or focus, and an overall decreased in sense of well-being. While each of these symptoms is related to low testosterone, they may also be related to other medical conditions such as thyroid problems, autoimmune disorders, side effects of medications and mental problems. Testosterone replacement therapy can help improve the signs and symptoms of low testosterone in men. Depending on the nature and severity of testosterone deficiency, doctors may prescribe testosterone in the form of injections, pellets, tablets, patches, or gels.

Insufficiency

Hypogonadism or testosterone deficiency is a condition in which the body does not produce sufficient levels of testosterone as a result of an underlying medical condition or other causes. It is likely that testosterone deficiency is under-diagnosed and is often mistaken for other medical conditions as its signs and symptoms resemble other diseases especially psychiatric disorders. Testosterone deficiency is classified according to the location of its cause:[13]

  • Primary: This type of testosterone deficiency is also known as primary testicular failure. The causes of the deficiency originate from a testicular problem.
  • Secondary: In this type of testosterone deficiency, the testicles are normal but its functions are altered due to a problem with the pituitary gland or hypothalamus (brain region that regulates temperature).

Hypogonadism may be present at birth (congenital) or may develop later in life (acquired). Congenital causes of hypogonadism include the following:

  • Klinefelter’s Syndrome: This condition results from a congenital abnormality of the sex chromosomes, X and Y. Normally, a male only has one X and one Y chromosome.[14] In this condition, two or more X chromosomes are present in addition to one Y chromosome. This causes the testicles to develop abnormally, which in turn affects the production of testosterone.
  • Undescended testicles (Cryptorchidism): Normally, the testicles move down the scrotum after birth.[15] Sometimes, one or both of the testicles may not descend and remain inside the abdomen. If not corrected in early childhood, it may affect the function of the testicles and reduce the rate at which testosterone is produced.
  • Kallmann syndrome: This condition is referred to as an abnormal development of the hypothalamus.[16] This abnormality can also affect the ability to smell (anosmia) and can lead to red-green color blindness.
  • Hemochromatosis: This condition occurs when there is too much iron in the blood.[17] As a result, the testicles or pituitary gland malfunctions, affecting the production of testosterone.

Acquired causes of testosterone deficiency include the following:

  • Injury or trauma to the testicles: This can impair blood flow going to the testicles and affect the production of testosterone.
  • Cancer treatment: Chemotherapy or radiation therapy can interfere with the production of sperm and testosterone.[18] Although the effects are temporary, there is still a chance that permanent infertility may occur.
  • Pituitary disorders: Any abnormality in the pituitary gland such as tumors can hinder the release of hormones from the pituitary gland to the testicles, thus affecting the production of testosterone.
  • Inflammatory disease: Tuberculosis, sarcoidosis and histiocytosis can affect the hypothalamus and pituitary gland, which in turn impair the production of testosterone.[19]
  • Autoimmune disorders: HIV/AIDS (Acquired immunodeficiency syndrome) can impair testosterone production by affecting the hypothalamus, the pituitary gland and the testes.[20]
  • Medications: Long-term use of medications for high cholesterol such as statins can lower testosterone levels as a side effect.[21]
  • Stress: Chronic stress raises the levels of the stress hormone called cortisol in response to the situation. This in turn suppresses the central hormone pathways which includes testosterone.[22]

Testosterone replacement in women

In women, testosterone may have a direct effect on libido and sexual response. However, there is no solid link between high testosterone level and high sex drive nor low testosterone and low sex drive.[23] Women can have low testosterone levels and have a normal sex drive or have high testosterone levels and little sexual desire. Sex drive in women may vary and is not affected by testosterone alone.

Research shows that testosterone replacement therapy for women does impact the sex drive and may help reduce symptoms associated with sexual dysfunction in women.[24] But the long-term safety of testosterone supplementation for women is still unclear. For this reason, prescription of testosterone for women might be appropriate if:

  • You have reduced sexual desire, depression, extreme fatigue, and mood changes after surgically induced menopause (if a woman had removal of the ovaries), and estrogen (hormone in women) therapy does not relieve your symptoms.[25]
  • You are postmenopausal and on estrogen therapy and have a decreased libido with no other identifiable causes.[26]

Testosterone Therapy for Specific Conditions

Increased longevity and population aging will increase your risk of developing late onset hypogonadism. It is a common condition, but is often mistaken for other medical conditions, making it frequently underdiagnosed and undertreated. The start of testosterone replacement therapy (TRT) requires the presence of below the normal testosterone levels, along with signs and symptoms of hypogonadism.

Although controversy remains regarding its use for the elderly due to lack of large-scale, long-term studies investigating its benefits and risks, reports indicate that TRT may produce a wide array of benefits for those with testosterone deficiency, including improvements in sexual desire and function, muscle mass, bone density, body composition, cognition, mood, erythropoiesis (red blood cell production), quality of life, and cardiovascular disease.[27]

Mood disorders and depression

Low testosterone can alter a person’s mood. Researchers first noticed the effects of low testosterone in animals. Since then, they have studied this effect in different kinds of mammals. The researchers observed that males with decreased testosterone become much more aggressive and prone to fighting instead of becoming docile and quiet.[28] Generally, questionnaires are used to monitor psychological factors, such as positive mood responses and negative mood responses.[29] Other studies have assessed similar attributes such as being angry, alert, energetic, irritable, tired, sad, nervous, and changes in well-being.[30] However, changes in mood parameters such as having low mood are generally experienced by hypogonadal men.

Testosterone replacement may have an antidepressant effect in individuals suffering from depression. To prove this, Zarrouf et al conducted both a systematic review of the literature and a meta-analysis that explores the effect of testosterone administration on depression.[31] The results of the meta-analysis of the data from seven studies showed a significant positive effect of testosterone therapy on Hamilton Rating Scale for Depression (HAM-D) response in depressed patients when compared with placebo. A related study by Pope et al also showed improvement in scores on the Hamilton Depression Rating Scale in men who had refractory depression and low or borderline testosterone levels who received transdermal testosterone gel supplementation for 8 weeks than subjects receiving placebo.[32]

Testosterone replacement therapy is considered as an effective treatment for depression related to low testosterone levels. Its efficacy is roughly equivalent to antidepressants such as selective serotonin reuptake inhibitor (SSRI) in minimizing the symptoms of depression. In one study, Seidman et al reported that 400 mg testosterone replacement biweekly for 8 weeks in five depressed men who had low testosterone levels and had not responded to SSRI showed improvements in depressive symptoms.[33]

Type 2 diabetes

Over the years, researchers have uncovered a significant connection between low testosterone and diabetes. In fact, men with type 2 diabetes are twice as likely to have low testosterone levels compared to men who don’t have diabetes.[34] Low levels of testosterone in men are associated with insulin resistance or reduced insulin sensitivity.[35] Insulin resistance is a medical condition wherein your body produces insulin but does not use it properly. This in turn leads to high blood glucose levels. Over time, insulin resistance can lead to type 2 diabetes and other health problems.

In one study, Kapoor et al investigated the effect of testosterone treatment on insulin resistance and glycemic control (blood sugar levels) in 24 hypogonadal men aged 30 and above with type 2 diabetes.[36] The researchers found that testosterone replacement therapy (TRT) reduces insulin resistance and improves blood sugar levels in all participants. A similar study involving 48 middle-aged men (24 subjects received testosterone for 3 months and 24 did not) with type 2 diabetes and symptoms of testosterone deficiency showed that oral testosterone treatment improves blood sugar levels, decreases visceral obesity, and improves symptoms of testosterone deficiency including erectile dysfunction.[37] In all of the participants, the benefit of oral testosterone supplementation therapy exceeds the correction of symptoms of testosterone deficiency.

Cognitive decline

As testosterone declines with age, so does cognitive function. Treating older men with testosterone may help improve spatial intelligence (deals with judgment and the ability to visualize) and verbal memory, according to a small study conducted by researchers at the University of Washington in Seattle.[38]

In another study, Cherrier et al investigated the effects of 6-week testosterone supplementation via injection among 19 men aged 63 to 85 years with Alzheimer disease (AD) or mild cognitive impairment (MCI).[39] Improvements in spatial memory, constructional abilities and verbal memory were evident and their levels of testosterone was raised by an average of 295%. In a related study by Ackermann et al, healthy subjects encoded pictures taken from the International Affective Picture System (IAPS) and they underwent a free recall test 10 minutes after memory encoding.[40] The study revealed that higher levels of testosterone were related to increased brain activation and that testosterone has a male-specific role in enhancing memory by increasing the biological salience of incoming information.

Osteoporosis and decreased bone density

As men age, their testosterone concentrations in the blood start to decline, as do their bone densities. When the level of bone density falls below the normal, osteoporosis can occur. The main characteristic of osteoporosis is reduction in bone density and quality, making affected individuals susceptible to fractures or bone breaks. There is a high incidence of early bone loss and low bone density (osteopenia) in men with low levels of testosterone which increases their risk for osteoporosis.[41] And the longer the duration of testosterone deficiency, the greater the risk.

Sex steroids in both sexes play a pivotal role in the maintenance of bone quality.[42] Because bone density is also low in hypogonadal men, testosterone replacement therapy would help increase their bone densities. In one study investigating the effect of testosterone treatment on bone mineral density in men over 65 years of age, Snyder et al reported that testosterone patch did increase bone mineral density of the lumbar spine as well as serum testosterone concentrations after 36 months of treatment.[43] In a similar study, Amory et al investigated the effects of testosterone therapy and finasteride, a 5 alpha-reductase inhibitor (prevents conversion of testosterone ) among 70 men aged 65 years and older with low testosterone levels for over 36 months.[44] The study showed that the combination of testosterone therapy and finasteride increases vertebral and hip bone mineral density (BMD).

Catabolic wasting

When a person suffers from loss of muscle and fat tissue due to chronic illness, this condition is called cachexia.[45] The general loss of weight and muscle mass that naturally occurs with advancing age is called sarcopenia.[46] The term “catabolic wasting” encompasses both of these medical conditions.

Testosterone plays a critical role in muscle building and maintaining muscle mass, and many muscle-wasted patients are deficient in testosterone.[47] One study reported that testosterone levels was deficient in over 70% of men with cancer cachexia.[48] The researchers observed that total testosterone levels were lower in cancer patients with cachexia compared to cancer patients without cachexia. A number of studies have reported that testosterone replacement therapy has been useful in promoting lean weight gain for patients with HIV/AIDS- or COPD-related cachexia.[49]

The oral testosterone derivative oxandrolone has been used for several years as a therapeutic intervention against unintentional weight loss associated with HIV/AIDS-related muscle wasting.[50] In a double-blind, randomized study, oxandrolone at doses of either 5 mg or 15 mg daily was effective in improving body weight and well-being in 63 HIV-positive men with weight loss of more than 10% of initial body weight.[51]  

HIV/AIDS

Most HIV-infected men with decreased testosterone levels have testosterone deficiency. Treatment of hypogonadal HIV-infected men with testosterone supplementation can lead to increased muscle mass and improvements in quality of life, and improvements in depression. In women, testosterone treatment has shown increase in weight and social functioning.[52]

In one study involving seventy-four HIV-infected patients who received bi-weekly testosterone injections followed by 12 weeks of open-label maintenance treatment for a period of 6 weeks, the results showed improvement in symptoms of clinical hypogonadism, thus restoring sex drive and energy, alleviating depression, and increasing muscle mass.[53] In another study, Coodley et al reported that 200 mg of testosterone cypionate injections every 2 weeks for 3 months in HIV-infected patients did appear to produce an improved overall sense of well-being and muscle strength.[54] The same researchers also investigated the effects of a steroid hormone called dehydroepiandrosterone (DHEA) in treating persistent depression in patients with HIV/AIDS.[55]   DHEA appears to be a useful treatment in reducing symptoms of non-major depression in HIV-infected patients.

Erectile dysfunction

Erections are clearly androgen-dependent. Testosterone has always been assumed to play a major role in erectile dysfunction (ED) because of the following reasons:

  • A decline in testosterone levels happens with ageing and a time period when the incidence of ED increases.[56]
  • Castration usually lead to impairment in sexual function.[57]
  • Sexual function returns to normal in castrated men with severe testosterone deficiency who undergo testosterone replacement therapy.[58]

In one study assessing the benefits of testosterone for ED, Kalinchenko et al reported that combining oral testosterone undecanoate with anti-diabetic drugs in diabetic patients who do not respond to Viagra therapy, has been observed to restore sexual function.[59] In a double-blind placebo controlled, cross-over study, Schiavi et al treated healthy men with erectile dysfunction with biweekly injections of 200 mg of testosterone enanthate for over a period of 6 weeks separated by a washout period of 4 weeks.[60] Results suggest that androgen administration among the subjects was able to increase ejaculatory frequency, reported sexual desire, masturbation, sexual experiences with partner, and sleep erections.

Testosterone in Athletics

Testosterone can be used to improve one’s performance. In sports, testosterone shots or creams are often promotes as magic bullets that spur athletes to run, jump, swim and to recover faster, and to become more aggressive and focused. However, it is considered to be a form of doping in most sports. Testosterone hormone supplements stimulate the endocrine system to adjust its production and lower the natural production of testosterone, so when it is discontinued, the natural production of the hormone is lower than before.[61] Anabolic steroids (including testosterone) have also been taken to build muscles, enhance strength, or endurance. They work directly by increasing the protein synthesis of the muscles leading to large muscle fibers and enhanced repairing ability.[62]   

After a series of scandals and publicity, such as Ben Johnson’s improved performance at the 1988 Summer Olympics, the use of anabolic steroids was banned by many sports organizations. In 1990, the United States Congress prohibited testosterone and other anabolic steroids, which were designated as controlled substances, resulting in the creation of the Anabolic Steroid Control Act.[63]   

Some female athletes may have naturally higher levels of the hormone testosterone than others, and may be asked by certain sports regulating bodies to consent to a “therapeutic proposal,” either surgery or drugs, to decrease testosterone levels to an acceptable level to compete fairly.[64]

History of testosterone’s use as an anabolic steroid

There is a significant difference between testosterone boosters and steroids. Testosterone boosters consist of natural ingredients and supplements such as those from plants,[65] while steroids are synthetic substances that are created in a laboratory and are usually prescribed by doctors to treat a variety of health related issues.[66] However, the use of steroids for the purpose of muscle building or enhancing an athlete’s performance without a prescription is illegal. There are two common steroids in the market: anabolic and androgenic steroids. Anabolic steroids are designed to promote muscle growth, while androgenic steroids are designed to assist with sexual dysfunction such as decreased libido and erectile dysfunction.[67] Most anabolic steroids are taken orally, through a pill, while others are injected.

Anabolic steroids did not receive a worldwide recognition until the 20th century, but the use of pure testosterone can be traced back to the original Olympic Games.[68] Early Olympic athletes were known to ingest animal testicles before a competition to improve their performance.[69] In 1935, researchers in the Netherlands were the first to isolate a few pure milligrams of testosterone. They named the substance “testosterone” from the words testicle, sterol, and the suffix of ketone.[70] Also during this year, Butenandt and Hanisch created the first synthetic version of testosterone from cholesterol.[71] It was made available to the medical community for experimentation and treatment purposes. Later, during World War II, it was found that this artificial form of testosterone helped malnourished soldiers gain weight and improved performance during combat.[72]

After the war, athletes began to use steroids to have an edge over other competitors. In the 1956 Olympics in Moscow, Soviet wrestlers performed at exceptionally high levels after using the male anabolic steroid testosterone.[73] After learning about this incident, an American physician named John Bosley Ziegler created a more selective form of what we know as anabolic steroids.[74] From that point until the early 1970s, the use of anabolic steroids became increasingly popular among Olympic athletes and professional sports players. In 1975, the International Olympic Committee finally prohibited the use of steroids and other performance-enhancing drugs in Olympic competition.[75] However, black market sales continued to increase in the following years.

In 1988, the Anti-Drug Abuse Act was introduced in order to stiffen the penalties for the sale and possession of anabolic steroids. In 1990, the United States Congress prohibited anabolic steroids and other performance-enhancing drugs and placed certain anabolic steroids on Schedule III of the Controlled Substances Act (CSA).[76] Previously, the use of steroids was controlled only by state laws. Today, illegal sales of steroids are still prevalent among athletes, bodybuilders, and even adolescents.

Effects and side effects of steroid use

There is a wide array of mild to serious side effects associated with abuse of anabolic steroids. The use of steroids in the long run can alter normal hormonal production in the body.[77] The user generally experiences an increase in muscle mass and strength very quickly. They experience heightened ability to lift heavier weights and train for more often and for longer periods of time because of their improved recovery rate.[78] However, the user can experience fluid retention, causing the muscle tissue to look soft and bloated. Side effects of steroid use vary depending on the user’s gender. Men may experience shrinkage of the penis and testicles, reduced sperm count, prostate problems, impotence, gynaecomastia (breast development), and baldness.[79] For women, steroid use can cause amenorrhea (loss of the menstrual cycle), facial and body hair, shrunken breasts, deepened voice, and abnormal growth of the clitoris.[80]

Users of anabolic steroids can display drug-seeking behavior as a result of physical and psychological drug dependency. Physical withdrawal can lead to mood swings, fatigue, loss of appetite, restlessness, sleep deprivation, reduced sex drive, steroid cravings, and in worst cases, depression that can lead to suicide.[81] Management for severe anabolic steroid addiction focuses on supportive treatments and medication intervention. However, most side effects can be reversed if steroid use is stopped.

Adverse effects and risks of testosterone use

Most of the studies done on the negative side effects of testosterone are anecdotal and based on case reports—no large retrospective or prospective studies investigating its adverse effects and risks have been conducted.[82] Some of the known adverse effects of testosterone use include the following:

  • Cardiovascular disease and stroke: Testosterone increases low density lipoproteins (LDL) or also known as the “bad cholesterol,” which can lead to clogs in the blood vessels and impair blood flow to heart and brain.[83]
  • Growth Defects: Steroid use especially among high school athletes can cause premature closure of the growth plate, leading to stunted growth.[84]
  • Kidney Problems: Toxic products like steroids put a great deal of strain on the kidneys and can lead to electrolyte imbalances and high blood pressure.[85]
  • Liver Problems: Steroids place great deal of stress on the liver which can lead to cholestasis (decrease in bile flow), hemorrhage, jaundice and even cancer.[86]
  • Skin Problems: Steroid use can lead to acne, oily skin and itchy rashes.[87]

The Food and Drug Administration (FDA) has required pharmaceutical companies to include warning information about the possibility of adverse effects such as increased risk of heart attacks and strokes in testosterone products.[88]

Testosterone and prostate cancer

Today, androgen deprivation or suppression therapy remains a cornerstone of treatment for men with advanced cancer of the prostate, so it’s no surprise that testosterone replacement therapy is contraindicated for those diagnosed with the disease. The traditional view was that testosterone fuels growth of cancer cells in the prostate and high levels of testosterone can possibly contribute to its spread.[89] Experts thought that cutting off the fuel supply—by administering androgen deprivation therapy to reduce testosterone levels—was an effective treatment.

In the past few years, some research has challenged many of these beliefs. Recently, there has been a paradigm shift whereby testosterone replacement therapy administration in prostate cancer patients has increased despite its supposed risk. Many longitudinal studies focusing on the relationship of endogenous testosterone levels and subsequent risk of prostate cancer failed to find any association.[90]

In a large meta-analysis of 18 prospective studies involving 3,886 men, there was no association between the risk of prostate cancer development and serum concentrations of testosterone.[91] Morgentaler et al proposed a saturation theory that explains why testosterone does not directly cause prostate cancer. According to his model, prostate cancer cells require a certain amount of testosterone in order to grow and multiply, and there is a limit to the ability of androgens to stimulate growth of prostate cancer cells.[92] That is why drastically reducing the levels of testosterone through hormone therapy can keep existing prostate cancer cells from growing. Normal prostate cells and even cancer cells seem to have a saturation point and are not affected as testosterone levels increase.      

In the latest meta-analysis presented in the American Urological Association 2015 Annual Meeting, Dr. Peter Boyle reported that testosterone, whether occurring naturally or taken as replacement therapy, does not cause prostate cancer or stimulate increases in the levels of prostate-specific antigen (PSA) in men.[93] However, even with the newest advances in testosterone research, most primary care physicians and various specialists continue to be hesitant about prescribing testosterone.

Testosterone and cardiac disease

Cardiovascular diseases are associated with insufficient level of the sex hormone testosterone.[94] In the largest study to date, Khaw et al investigated the effects of testosterone levels and mortality among 11,606 healthy men aged 40 to 79 years old over a 6- to 10-year follow-up period and observed a significant association between low levels of testosterone and increased risk of cardiovascular diseases.[95]

In the most recent study, Dr. Barua, an assistant professor of medicine at the University of Kansas School of Medicine, and his colleagues reported that testosterone supplementation can reduce the risk of myocardial infarction (MI), stroke, and all-cause mortality at normal levels.[96] In hopes of providing some answers to testosterone and cardiac disease association, the study team retrospectively examined national data on 83,010 men (aged 50 and above) with documented low testosterone who received care from the Veteran’s Administration between 1999 and 2014. The results of the study showed that treated men with testosterone levels at normal range were 56% less likely to die during the follow-up period, 24% less likely to suffer a myocardial infarction, and 36% less likely to have a stroke.[96]

Measuring testosterone levels and route of administration

Symptoms associated with low testosterone level may resemble other medical conditions such as thyroid problems, hormonal imbalance, side effects of medications and illegal drugs, and mental problems. To determine what’s causing these symptoms, it is recommended to schedule an appointment with your doctor for a blood test. Test to determine testosterone levels should be done in the morning between 7:00 and 10:00 am.[97] For normal results, the test should be repeated to make sure that the result is accurate. In healthy men, the levels of testosterone can change a lot from day to day, so a second test is required.

 

After the decision to restore testosterone levels has been made, the next step is deciding on the most effective route of administration. There are several different modes in which testosterone can be delivered, but the best method varies from person to person. A number of factors should be considered when selecting a specific testosterone modality for replacement therapy. These factors include the following:[98]

 

  • Acceptability of the therapy to the individual patient
  • Adverse effects of the therapy in general and of a particular preparation
  • Efficacy of the treatment, which relates to the levels of the testosterone obtained

 

Types of testosterone tests

A testosterone test, also called serum testosterone test, measures the amount of testosterone in the blood. This test is ordered to determine if a person has low levels of testosterone. It is important to inform your doctor about your current medications as it may affect the result of the test. Medications that can alter testosterone test results are steroids, anticonvulsants, barbiturates, clomiphene, and estrogen therapy.[99]

The levels of testosterone in the blood can be measured in terms of total, bio-available, or free testosterone and there are various tests which can be used to measure each type of testosterone:

  • Total testosterone: This test measures free, albumin-bound and sex hormone binding globulin (SHBG) bound testosterone and is the most commonly used blood test.[100] Total testosterone blood test is used to assess testosterone levels in patients with suspected hypogonadism.
  • Bioavailable testosterone: This test measures both free and albumin-bound testosterone, both of which are available for use by cells in the body.[100]
  • Free testosterone: This test measures only the 2% of testosterone that remains unbound to proteins in the blood.[101] Free testosterone levels can also be measured through the saliva.

Types of testosterone therapy

The different methods of testosterone delivery are the following:

 

  • Intramuscular Injections: This method of testosterone delivery has been used for years because it is cost-effective and has longer duration of action. It has a 100% success rate in providing usable hormone. This method allows precise control of the dosage of testosterone administered and is considered the most effective testosterone replacement method.[102] However, intramuscular testosterone injections are deep and painful, and can lead to site reactions or itchiness.[103] It can also cause mild gynecomastia (breast enlargement in men) early in the treatment process which usually resolve within a few months.
  • Implantable Testosterone: This method makes use of pellets containing 75 mg of crystalline testosterone that are implanted beneath the skin of the upper thighs, deltoid, gluteal muscles, or lower abdomen to provide slow release over 4 to 6 months.[104] Pellets can be quite painful as it requires surgical implantation. They have also a higher rate of thrusting out of the implanted area. Furthermore, testosterone pellets have long duration of action and reversibility is difficult, thus making them incompatible for elderly patients, in whom adverse effects are more common.
  • Transbuccal System: It is administered through a small tablet that adheres to the gum tissue. It is slowly absorbed. Transbuccal tablets contain 30 mg of testosterone, which peaks within 30 minutes and attain steady state within 24 hours.[105] This mode of treatment can lead to mild to moderate gum or mouth irritation, tenderness, and bitter taste. Other potential concerns include inadvertent swallowing of the transbuccal tablets and transfer of salivary testosterone to the partner.
  • Transdermal Testosterone: This method can be applied through a patch or gel. Transdermal testosterone mimics the normal circadian rhythm of testosterone, peaking in the morning and declining to its lowest point at night.[106] Another advantage is that it doesn’t affect the levels of cholesterol such as high density lipoprotein the way injectable and oral testosterone formulation does.[107] The patch is applied at bedtime to the abdomen, upper thighs, upper arms, or back. The most common problem encountered with testosterone patches is the high incidence of skin irritation at the application site. TRT gel is the most expensive of the TRT modalities but is currently the most commonly used.[108] Testosterone gel is applied to dry skin on the abdomen, upper arm, or shoulder after bathing. Compared with the patch, the testosterone gel rarely causes skin irritation at the application site.
  • Oral Testosterone: Oral testosterones such as oxandrolone, danazol, fluoxynesterone, or methyltestosterone are available for clinical use, but are not recommended for long-term use as they can increase liver enzymes, block liver drainage pathways, and cause liver damage and tumors.[109] Testosterone undecanoate is an oral testosterone compound commonly used today because it is able to bypass the liver, thus minimizing adverse side effects.[110]

 


 

References:

  1. Michael Selzer; Stephanie Clarke; Leonardo Cohen; Pamela Duncan, Fred Gage (16 February 2006). Textbook of Neural Repair and Rehabilitation: Volume 2, Medical Neurorehabilitation. Cambridge University Press. pp. 401–. ISBN 978-1-139-45084-3.
  2. Carol Leth Stone (2011). Geriatrics. ABC-CLIO. pp. 34–. ISBN 978-0-313-37618-4.
  3. Shawn M. Talbott; William J. Kraemer (2007). The Cortisol Connection: Why Stress Makes You Fat and Ruins Your Health – And What You Can Do about It. Hunter House. pp. 67–. ISBN 978-0-89793-492-3.
  4. Gary Null (2003). Bottom Line’s Power Aging: The Revolutionary Program to Control the Symptons of Aging Naturally. Stranger Journalism. pp. 53–. ISBN 978-0-88723-445-3.
  5. Theresa Cheung (1999). Androgen Disorders in Women: The Most Neglected Hormone Problem. Hunter House. pp. 30–. ISBN 978-0-89793-259-2.
  6. Frances Talaska Fischbach; Marshall Barnett Dunning (2009). A Manual of Laboratory and Diagnostic Tests. Lippincott Williams & Wilkins. pp. 407–. ISBN 978-0-7817-7194-8.
  7. Victor R. Preedy (2 February 2012). Handbook of Anthropometry: Physical Measures of Human Form in Health and Disease. Springer Science & Business Media. pp. 1483–. ISBN 978-1-4419-1788-1.
  8. Marc A. Fritz; Leon Speroff (28 March 2012). Clinical Gynecologic Endocrinology and Infertility. Lippincott Williams & Wilkins. pp. 48–. ISBN 978-1-4511-4847-3.
  9. David Stuart Sobel; Tom Ferguson (1985). The People’s Book of Medical Tests. Summit Books. ISBN 978-0-671-44172-2.
  10. Staness Jonekos; Marjorie Jenkins (1 April 2014). Eat Like a Woman: A 3-Week, 3-Step Program to Finally Drop the Pounds and Feel Better Than Ever. pp. 55–. ISBN 978-1-4603-2868-2.
  11. Michał Karasek (2006). Aging and Age-related Diseases: The Basics. Nova Publishers. pp. 41–. ISBN 978-1-59454-426-2.
  12. Aldo Pinchera; Xavier Bertagna; Lewis Edward Braverman; Jan Fischer (2001). Endocrinology and Metabolism. McGraw-Hill International (UK) Limited. ISBN 978-0-07-709520-8.
  13. Basu SC (30 May 2011). Male Reproductive Dysfunction. Jaypee Brothers Publishers. pp. 59–. ISBN 978-93-5025-220-8.
  14. Virginia Isaacs Cover (1 March 2012). Living with Klinefelter Syndrome (47, Xxy) Trisomy X (47, XXX) and 47, Xyy: A Guide for Families and Individuals Affected by X and Y Chromosome Variation. Virginia Isaacs Cover. ISBN 978-0-615-57400-4.
  15. Carol Porth (2011). Essentials of Pathophysiology: Concepts of Altered Health States. Lippincott Williams & Wilkins. pp. 1029–. ISBN 978-1-58255-724-3.
  16. Shlomo Melmed; P.Michael Conn (5 November 2007). Endocrinology: Basic and Clinical Principles. Springer Science & Business Media. pp. 237–. ISBN 978-1-59259-829-8.
  17. Zina Kroner (8 April 2011). Vitamins and Minerals. ABC-CLIO. pp. 166–. ISBN 978-0-313-38225-3.
  18. Teri Moser Woo; Anita Lee Wynne (2 August 2011). Pharmacotherapeutics for Nurse Practitioner Prescribers.A. Davis. pp. 1393–. ISBN 978-0-8036-2660-7.
  19. Larry Jameson (13 July 1998). Principles of Molecular Medicine. Springer Science & Business Media. pp. 604–. ISBN 978-1-59259-726-0.
  20. Gene M. Shelling (2006). AIDS Policies and Programs. Nova Publishers. pp. 165–. ISBN 978-1-60021-217-8.
  21. Khaldoun Sharif; Arri Coomarasamy (19 January 2012). Assisted Reproduction Techniques: Challenges and Management Options. John Wiley & Sons. pp. 49–. ISBN 978-1-4443-9883-0.
  22. Mary Frances Asterita (1985). The Physiology of Stress: With Special Reference to the Neuroendocrine System. Human Sciences Press. ISBN 978-0-89885-176-2.
  23. Roy F. Baumeister; Brad Bushman (1 January 2013). Social Psychology and Human Nature, Comprehensive Edition. Cengage Learning. 425–. ISBN 978-1-305-16166-5.
  24. Douglas E. Rosenau (21 November 2002). A Celebration Of Sex: A Guide to Enjoying God’s Gift of Sexual Intimacy. Thomas Nelson. pp. 234–. ISBN 978-1-4185-9040-6.
  25. Jason Abbott; Lucy Bowyer; Martha Finn (2 June 2014). Obstetrics and Gynaecology: an evidence-based guide. Elsevier Health Sciences APAC. pp. 255–. ISBN 978-0-7295-8073-1.
  26. Nanette Santoro (7 September 2015). Postmenopausal Endocrinology, an Issue of Endocrinology and Metabolism Clinics of North America. Elsevier Health Sciences. pp. 657–. ISBN 978-0-323-39561-8.
  27. Bassil N, Alkaade S, Morley JE. The benefits and risks of testosterone replacement therapy: a review. Ther Clin Risk Manag. 2009;5(3):427-48.
  28. Tom Sherlock (15 April 2013). Colorado’s Healthcare Heritage: A Chronology of the Nineteenth and Twentieth Centuries Volume One — 1800-1899. iUniverse. pp. 46–. ISBN 978-1-4759-8026-4.
  29. The Journal of Clinical Endocrinology & Metabolism, Aug 1 2000, 85(8):2839-2853, “Transdermal Testosterone Gel Improves Sexual Function, Mood, Muscle Strength, and Body Composition Parameters in Hypogonadal Men”.
  30. J Clin Endocrinol Metab, 1996 Oct, 81(10):3578-83, “Testosterone replacement therapy improves mood in hypogonadal men–a clinical research center study”.
  31. Zarrouf FA, Artz S, Griffith J, Sirbu C, Kommor M. Testosterone and depression: systematic review and meta-analysis. J Psychiatr Pract. 2009;15(4):289-305.
  32. Pope HG, Cohane GH, Kanayama G, Siegel AJ, Hudson JI. Testosterone gel supplementation for men with refractory depression: a randomized, placebo-controlled trial. Am J Psychiatry. 2003;160(1):105-11.
  33. Seidman SN, Rabkin JG. Testosterone replacement therapy for hypogonadal men with SSRI-refractory depression. J Affect Disord. 1998;48(2-3):157-61.
  34. Roger S. Kirby; Culley C. Carson; Michael G. Kirby; Alan White (29 January 2009). Men’s Health, Third Edition. Taylor & Francis. ISBN 978-0-415-44733-1.
  35. Eberhard Nieschlag; Hermann M. Behre; Susan Nieschlag (26 July 2012). Testosterone: Action, Deficiency, Substitution. Cambridge University Press. pp. 241–. ISBN 978-1-107-01290-5.
  36. Kapoor D, Goodwin E, Channer KS, Jones TH. Testosterone replacement therapy improves insulin resistance, glycaemic control, visceral adiposity and hypercholesterolaemia in hypogonadal men with type 2 diabetes. Eur J Endocrinol. 2006;154(6):899-906.
  37. Boyanov MA, Boneva Z, Christov VG. Testosterone supplementation in men with type 2 diabetes, visceral obesity and partial androgen deficiency. Aging Male. 2003;6(1):1-7.
  38. Can testosterone improve memory in men? Study provides initial findings. Available at: http://www.washington.edu/news/1998/06/25/can-testosterone-improve-memory-in-men-study-provides-initial-findings/. Accessed January 29, 2016.
  39. Cherrier MM, Matsumoto AM, Amory JK, et al. Testosterone improves spatial memory in men with Alzheimer disease and mild cognitive impairment. 2005;64(12):2063-8.
  40. Ackermann S, Spalek K, Rasch B, et al. Testosterone levels in healthy men are related to amygdala reactivity and memory performance. 2012;37(9):1417-24.
  41. Markus J. Seibel; Simon P. Robins; John P. Bilezikian (24 July 2006). Dynamics of Bone and Cartilage Metabolism: Principles and Clinical Applications. Academic Press. pp. 677–. ISBN 978-0-08-045626-3.
  42. Cilotti A, Falchetti A. Male osteoporosis and androgenic therapy: from testosterone to SARMs. Clin Cases Miner Bone Metab. 2009;6(3):229-33.
  43. Snyder PJ, Peachey H, Hannoush P, et al. Effect of testosterone treatment on bone mineral density in men over 65 years of age. J Clin Endocrinol Metab. 1999;84(6):1966-72.
  44. Exogenous testosterone or testosterone with finasteride increases bone mineral density in older men with low serum testosterone. Available at: http://www.pubfacts.com/detail/14764753/Exogenous-testosterone-or-testosterone-with-finasteride-increases-bone-mineral-density-in-older-men-. Accessed January 30, 2016.
  45. Karl G. Hofbauer; Stefan D. Anker; Akio Inui; Janet R. Nicholson (22 December 2005). Pharmacotherapy of Cachexia. CRC Press. ISBN 978-1-4200-4895-7.
  46. Gordon S. Lynch (30 November 2010). Sarcopenia – Age-Related Muscle Wasting and Weakness: Mechanisms and Treatments. Springer Science & Business Media. ISBN 978-90-481-9713-2.
  47. Jacob Teitelbaum (2001). From Fatigued to Fantastic!: A Proven Program to Regain Vibrant Health, Based on a New Scientific Study Showing Effective Treatment for Chronic Fatigue and Fibromyalgia. Penguin. pp. 48–. ISBN 978-1-58333-097-5.
  48. Burney BO, Hayes TG, Smiechowska J, et al. Low testosterone levels and increased inflammatory markers in patients with cancer and relationship with cachexia. J Clin Endocrin Metab 2012;97(5):E700-E709.
  49. Gullett NP, Hebbar G, Ziegler TR. Update on clinical trials of growth factors and anabolic steroids in cachexia and wasting. Am J Clin Nutr 2010;91(supplement):1143-1147S.
  50. Nicholas H. Fiebach; Lee Randol Barker; John Russell Burton; Philip D. Zieve (2007). Principles of Ambulatory Medicine. Lippincott Williams & Wilkins. pp. 425–. ISBN 978-0-7817-6227-4.
  51. Berger JR, Pall L, Hall CD, Simpson DM, Berry PS, Dudley R. Oxandrolone in AIDS-wasting myopathy. AIDS (London, England). Dec 1996;10(14):1657-1662.
  52. Wayne Meikle (24 April 2003). Endocrine Replacement Therapy in Clinical Practice. Springer Science & Business Media. pp. 419–. ISBN 978-1-59259-375-0.
  53. Rabkin JG, Wagner GJ, Rabkin R. A double-blind, placebo-controlled trial of testosterone therapy for HIV-positive men with hypogonadal symptoms. Arch Gen Psychiatry. 2000;57(2):141-7.
  54. Coodley GO, Coodley MK. A trial of testosterone therapy for HIV-associated weight loss. 1997;11(11):1347-52.
  55. Rabkin JG, Mcelhiney MC, Rabkin R, Mcgrath PJ, Ferrando SJ. Placebo-controlled trial of dehydroepiandrosterone (DHEA) for treatment of nonmajor depression in patients with HIV/AIDS. Am J Psychiatry. 2006;163(1):59-66.
  56. Morley JE, Kaiser FE, Perry HM, et al. Longitudinal changes in testosterone, luteinizing hormone, and follicle-stimulating hormone in healthy older men. Metab Clin Exp. 1997;46(4):410-3.
  57. Rousseau L, Dupont A, Labrie F, Couture M. Sexuality changes in prostate cancer patients receiving antihormonal therapy combining the antiandrogen flutamide with medical (LHRH agonist) or surgical castration. Arch Sex Behav. 1988;17(1):87-98.
  58. Davidson JM, Camargo CA, Smith ER. Effects of androgen on sexual behavior in hypogonadal men. J Clin Endocrinol Metab. 1979;48(6):955-8.
  59. Kalinchenko SY, Kozlov GI, Gontcharov NP, Katsiya GV. Oral testosterone undecanoate reverses erectile dysfunction associated with diabetes mellitus in patients failing on sildenafil citrate therapy alone. Aging Male. 2003;6(2):94-9.
  60. Schiavi RC, White D, Mandeli J, Levine AC. Effect of testosterone administration on sexual behavior and mood in men with erectile dysfunction. Arch Sex Behav. 1997;26(3):231-41.
  61. William D. Schraer; Herbert J. Stoltze (1 January 1992). Biology: the study of life. Prentice Hall. ISBN 978-0-13-083304-4.
  62. William N. Taylor, M.D. (16 January 2002). Anabolic Steroids and the Athlete, 2d ed. pp. 31–. ISBN 978-0-7864-1128-3.
  63. Nicolae Sfetcu (2 May 2014). Health & Drugs: Disease, Prescription & Medication. Nicolae Sfetcu. pp. 1157–. GGKEY:JPFE1Q59083.
  64. Karkazis K, Jordan-Young R (April 11, 2014). “The Trouble With Too Much T”. New York Times. Retrieved April 12, 2014.
  65. Kimberly Mueller; Josh Hingst (2013). The Athlete’s Guide to Sports Supplements. Human Kinetics. pp. 91–. ISBN 0-7360-9369-9.
  66. Larry J. Siegel; Brandon C. Welsh (14 May 2010). Juvenile Delinquency: The Core. Cengage Learning. pp. 257–. ISBN 0-495-80986-1.
  67. Mechanism of Action of Anabolic-androgenic Steroids. ProQuest. 2008. pp. 4–. ISBN 978-0-549-65265-6.
  68. Facts On File, Incorporated (2007). Drugs and Sports. Infobase Publishing. pp. 111–. ISBN 978-1-4381-2444-5.
  69. Linda E. Swayne; Mark Dodds (8 August 2011). Encyclopedia of Sports Management and Marketing. SAGE Publications. pp. 610–. ISBN 978-1-5063-2037-3.
  70. Edmund Vincent Cowdry (1944). A textbook of histology: functional significance of cells and intercellular substances. Lea & Febiger.
  71. A4M American Academy of Anti-Aging Medicine (13 March 2015). Anti-Aging Therapeutics Volume XVI. A4M American Academy of Anti-Aging Medicine. pp. 98–. ISBN 978-1-934715-17-8.
  72. Aharon W. Zorea Ph.D. (25 April 2014). ABC-CLIO. pp. 25–. ISBN 978-1-4408-0300-0.
  73. David Levinson; Karen Christensen (1999). Encyclopedia of World Sport: From Ancient Times to the Present. Oxford University Press. pp. 110–. ISBN 978-0-19-513195-6.
  74. Danielle Sarver Coombs; Bob Batchelor (2013). American History Through American Sports: From Colonial Lacrosse to Extreme Sports. ABC-CLIO. pp. 2–. ISBN 978-0-313-37988-8.
  75. Thomas M. Hunt (15 January 2011). Drug Games: The International Olympic Committee and the Politics of Doping, 1960–2008. University of Texas Press. pp. 54–. ISBN 978-0-292-73957-4.
  76. Edith Fairman Cooper (2002). The Emergence of Crack Cocaine Abuse. Nova Publishers. pp. 63–. ISBN 978-1-59033-512-3.
  77. William David Hager; Linda Carruth Hager (1 September 1998). Stress and the Woman’s Body. Baker Publishing Group. ISBN 978-0-8007-5665-9.
  78. Gross (11 December 2013). Protein Metabolism: Influence of Growth Hormone, Anabolic Steroids, and Nutrition in Health and Disease. An International Symposium Leyden, 25th–29th June, 1962. Springer. pp. 212–. ISBN 978-3-642-53147-7.
  79. Gerard Thorne; Phil Embleton (1997). Robert Kennedy’s Musclemag International Encyclopedia of Bodybuilding: The Ultimate A-Z Book on Muscle Building!. Musclemag International. ISBN 978-1-55210-001-1.
  80. Linda Lewis Alexander (1 March 2013). New Dimensions in Women’s Health. Jones & Bartlett Publishers. pp. 264–. ISBN 978-1-4496-8375-7.
  81. Thomas J. Rundquist (1 March 2001). Drug Addict Trivia Game. Nova Media Inc. pp. 138–. ISBN 978-1-884239-55-7.
  82. Dan J Stein, MD; David J. Kupfer; Alan F. Schatzberg (2005). The American Psychiatric Publishing Textbook of Mood Disorders. American Psychiatric Pub. ISBN 978-1-58562-151-4.
  83. Hans Selye (17 April 2013). Hormones and Resistance: Part 1 and. Springer Science & Business Media. pp. 219–. ISBN 978-3-642-65192-2.
  84. William Llewellyn (2011). Anabolics. Molecular Nutrition Llc. pp. 67–. ISBN 978-0-9828280-1-4.
  85. Jeff Rutstein (1 July 2005). The Steroid Deceit: A Body Worth Dying For?. Custom Fitness Publishing, LLC. pp. 63–. ISBN 978-0-9760170-2-8.
  86. Arnold Schwarzenegger (3 July 2012). The New Encyclopedia of Modern Bodybuilding: The Bible of Bodybuilding, Fully Updated and Revis. Simon and Schuster. pp. 1565–. ISBN 978-1-4516-9713-1.
  87. Lawrence Clayton (1 October 1998). Steroids. The Rosen Publishing Group. pp. 30–. ISBN 978-0-8239-2888-0.
  88. Staff (3 March 2015). “Testosterone Products: Drug Safety Communication – FDA Cautions About Using Testosterone Products for Low Testosterone Due to Aging; Requires Labeling Change to Inform of Possible Increased Risk of Heart Attack And Stroke”. Retrieved 2 February 2016.
  89. James Gilbaugh (11 May 2010). Men’s Private Parts: A Pocket Reference to Prostrate, Urologic, and Sex. Simon and Schuster. pp. 74–. ISBN 978-1-4391-4550-0.
  90. Morgentaler A. Testosterone therapy for men at risk for or with history of prostate cancer. Curr Treat Options Oncol. 2006;7(5):363-9.
  91. Roddam AW, Allen NE, Appleby P, Key TJ. Endogenous sex hormones and prostate cancer: a collaborative analysis of 18 prospective studies. J Natl Cancer Inst. 2008;100(3):170-83.
  92. Morgentaler A, Traish AM. Shifting the paradigm of testosterone and prostate cancer: the saturation model and the limits of androgen-dependent growth. Eur Urol. 2009;55(2):310-20.
  93. American Urological Association (AUA) 2015 Annual Meeting: Abstract MP4-09. Presented May 15, 2015.
  94. Granata; J. Isgaard (12 June 2014). Cardiovascular Issues in Endocrinology. Karger Medical and Scientific Publishers. pp. 70–. ISBN 978-3-318-02674-0.
  95. Khaw KT, Dowsett M, Folkerd E, et al. Endogenous testosterone and mortality due to all causes, cardiovascular disease, and cancer in men: European prospective investigation into cancer in Norfolk (EPIC-Norfolk) Prospective Population Study. 2007;116(23):2694-701.
  96. No Cardiovascular Risk Seen in Latest Testosterone Study. Medscape. Aug 14, 2015.
  97. Lynne M Dunphy; Jill Winland-Brown; Brian Porter; Debera Thomas (19 February 2015). Primary Care: Art and Science of Advanced Practice Nursing. F.A. Davis. pp. 643–. ISBN 978-0-8036-4494-6.
  98. Tenover JL. The androgen-deficient aging male: current treatment options. Rev Urol. 2003;5 Suppl 1:S22-8.
  99. Kathleen Deska Pagana (8 November 2013). Mosby’s Manual of Diagnostic and Laboratory Tests. Elsevier Health Sciences. pp. 477–. ISBN 978-0-323-08949-4.
  100. John Whyte (2 August 2011). Is This Normal?: The Essential Guide to Middle Age and Beyond. pp. 194–. ISBN 978-1-60961-122-4.
  101. Eberhard Nieschlag; Hermann Behre (29 June 2013). Andrology: Male Reproductive Health and Dysfunction. Springer Science & Business Media. pp. 102–. ISBN 978-3-662-04491-9.
  102. M. Swartz M.D.; Y.L. Wright M.A. (9 March 2015). MEN’S HORMONES MADE EASY!: How to Treat Low Testosterone, Low Growth Hormone, Erectile Dysfunction, BPH, Andropause, Insulin Resistance, Adrenal Fatigue, Thyroid, Osteoporosis, High Estrogen, and DHT!. Lulu.com. pp. 130–. ISBN 978-1-312-86059-9.
  103. Dobs AS, Meikle AW, Arver S, Sanders SW, Caramelli KE, Mazer NA. Pharmacokinetics, efficacy, and safety of a permeation-enhanced testosterone transdermal system in comparison with bi-weekly injections of testosterone enanthate for the treatment of hypogonadal men. J Clin Endocrinol Metab. 1999;84(10):3469-3478.
  104. Russell La Fayette Cecil; Lee Goldman (MD.); Andrew I. Schafer (2012). Goldman’s Cecil Medicine,Expert Consult Premium Edition — Enhanced Online Features and Print, Single Volume,24: Goldman’s Cecil Medicine. Elsevier Health Sciences. pp. 1525–. ISBN 1-4377-1604-0.
  105. Ross RJ, Jabbar A, Jones TH, et al. Pharmacokinetics and tolerability of a bioadhesive buccal testosterone tablet in hypogonadal men. Eur J Endocrinol. 2004;150(1):57-63.
  106. Meikle AW, Mazer NA, Moellmer JF, et al. Enhanced transdermal delivery of testosterone across nonscrotal skin produces physiological concentrations of testosterone and its metabolites in hypogonadal men. J Clin Endocrinol Metab. 1992;74(3):623-628.
  107. Tenover JL. The androgen-deficient aging male: Current treatment options. Rev Urol. 2003;5(suppl 1):S22-S28.
  108. The extent and nature of testosterone use. IMS web site. www.imshealth.com/portal/front/articleC/0,2777,6599_5266_43871355,00.html. Accessed February 3, 2016.
  109. Peter R McNally (17 November 2014). GI/Liver Secrets Plus. Elsevier Health Sciences. pp. 188–. ISBN 978-0-323-31577-7.
  110. Marcus I. Portallis (2004). Focus on Hormone Replacement Research. Nova Publishers. pp. 137–. ISBN 978-1-59033-963-3.

Categories

Testosterone Fights Inflammation

Friday, February 12th, 2016 | No Comment

Chronic inflammation is one of the most insidious threats to health today—and research is increasingly establishing a link between testosterone deficiency and inflammation. This is especially true for women, who have naturally lower levels of testosterone than men, which may help explain why they are at higher risk for certain […]

Read More