Testosterone begins with cholesterol. In fact, every single sex hormone you make you synthesize from cholesterol – that’s one reason a “heart healthy” low-fat, low-cholesterol diet limits your performance. Fat and cholesterol don’t make you fat. They give your body the building blocks to create abundant testosterone and other sex hormones, which actually makes you lose weight and build muscle, especially if your current testosterone levels are low [1].

Some self-administered measures may be useful in the primary care setting to screen for and evaluate the degree of ED.12 The most commonly used instrument is the International Index of Erectile Function, a 15-item questionnaire that has been validated in many populations and is considered the gold standard to evaluate patients for ED.13 The Sexual Health Inventory for Men is a short-form, 5-item questionnaire developed to monitor treatment progress.12 It is important to recognize that short-form questionnaire does not evaluate specific areas of the sexual cycle, such as sexual desire, ejaculation, and orgasm; however, it may be useful in discussing ED with patients and evaluating treatment results over time.
Other factors leading to erectile dysfunction are diabetes mellitus, which is a well-known cause of neuropathy).[1] ED is also related to generally poor physical health, poor dietary habits, obesity, and most specifically cardiovascular disease, such as coronary artery disease and peripheral vascular disease.[1] Screening for cardiovascular risk factors, such as smoking, dyslipidemia, hypertension, and alcoholism is helpful.[1]
Impotence is a common problem among men and is characterized by the consistent inability to sustain an erection sufficient for sexual intercourse or the inability to achieve ejaculation, or both. Erectile dysfunction can vary. It can involve a total inability to achieve an erection or ejaculation, an inconsistent ability to do so, or a tendency to sustain only very brief erections.
A physical cause can be identified in about 80% of cases.[1] These include cardiovascular disease, diabetes mellitus, neurological problems such as following prostatectomy, hypogonadism, and drug side effects. Psychological impotence is where erection or penetration fails due to thoughts or feelings; this is somewhat less frequent, in the order of about 10% of cases.[1] In psychological impotence, there is a strong response to placebo treatment.
THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for general informational purposes only and does not address individual circumstances. It is not a substitute for professional medical advice, diagnosis or treatment and should not be relied on to make decisions about your health. Never ignore professional medical advice in seeking treatment because of something you have read on the WebMD Site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
Diabetes is a well-recognized risk factor for ED. A systematic review and meta-analysis found that the prevalence of ED was 37.5% in type 1 diabetes, 66.3% in type 2 diabetes, and 52.5% in diabetes overall—a rate approximately 3.5 times higher than that in controls. [39]  The etiology of ED in diabetic men probably involves both vascular and neurogenic mechanisms. Evidence indicates that establishing good glycemic control can minimize this risk.
When stimulated by the nerves, the spongy tissue arranges itself in such a way that more blood can be stored in the penis. The veins running through the outer sheath of the penis then compress which stops the blood from leaving the penis. As the blood is stopped from flowing out, the penis fills with blood and stretches within the outer casing, giving an erection.
Hypogonadism (as well as age-related low testosterone) is diagnosed with blood tests that measure the level of testosterone in the body. The Endocrine Society recommends testing for suspected low T with a total testosterone test. It may be performed in the morning when testosterone levels tend to be highest in young men, although this isn't necessarily the case in older men. The test may be repeated on another day if the results show a low T level. (5)
Camacho EM1, Huhtaniemi IT, O'Neill TW, Finn JD, Pye SR, Lee DM, Tajar A, Bartfai G, Boonen S, Casanueva FF, Forti G, Giwercman A, Han TS, Kula K, Keevil B, Lean ME, Pendleton N, Punab M, Vanderschueren D, Wu FC; EMAS Group. “Age-associated changes in hypothalamic-pituitary-testicular function in middle-aged and older men are modified by weight change and lifestyle factors: longitudinal results from the European Male Ageing Study.” Eur J Endocrinol. 2013 Feb 20;168(3):445-55. doi: 10.1530/EJE-12-0890. Print 2013 Mar.

ED can also occur among younger men. A 2013 study found that one in four men seeking their first treatment for ED were under the age of 40. The researchers found a stronger correlation between smoking and illicit drug use and ED in men under 40 than among older men. That suggests that lifestyle choices may be a main contributing factor for ED in younger men.
“Although having sex at 70 is not the same as having sex at 20, erectile dysfunction is not a normal part of aging,” according to Michael Feloney, MD, urologic surgeon and expert on sexual dysfunction issues at the Nebraska Medical Center in Omaha. “You should still be able to have a satisfying sex life as you age." If you are experiencing erectile dysfunction, these 10 dos and don'ts may help.
The effects of testosterone in humans and other vertebrates occur by way of multiple mechanisms: by activation of the androgen receptor (directly or as DHT), and by conversion to estradiol and activation of certain estrogen receptors.[105][106] Androgens such as testosterone have also been found to bind to and activate membrane androgen receptors.[107][108][109]
When a man becomes sexually excited, muscles in their penis relax. This relaxation allows for increased blood flow through the penile arteries. This blood fills two chambers inside the penis called the corpora cavernosa. As the chambers fill with blood, the penis grows rigid. Erection ends when the muscles contract and the accumulated blood can flow out through the penile veins.

The bones and the brain are two important tissues in humans where the primary effect of testosterone is by way of aromatization to estradiol. In the bones, estradiol accelerates ossification of cartilage into bone, leading to closure of the epiphyses and conclusion of growth. In the central nervous system, testosterone is aromatized to estradiol. Estradiol rather than testosterone serves as the most important feedback signal to the hypothalamus (especially affecting LH secretion).[111] In many mammals, prenatal or perinatal "masculinization" of the sexually dimorphic areas of the brain by estradiol derived from testosterone programs later male sexual behavior.[112]
Overall, it seems that both estrogen and testosterone are important for normal bone growth and maintenance. Deficiency or failure of action of the sex hormones is associated with osteoporosis and minimal trauma fractures. Estrogen in males is produced via metabolism of testosterone by aromatase and it is therefore important that androgens used for the treatment of hypogonadism be amenable to the action of aromatase to yield maximal positive effects on bone. There is data showing that testosterone treatment increases bone mineral density in aging males but that these benefits are confined to hypogonadal men. The magnitude of this improvement is greater in the spine than in the hip and further studies are warranted to confirm or refute any differential effects of testosterone at these important sites. Improvements seen in randomized controlled trials to date may underestimate true positive effects due to relatively short duration and/or baseline characteristics of the patients involved. There is no data as yet to confirm that the improvement in bone density with testosterone treatment reduces fractures in men and this is an important area for future study.

Regular exercise for about 20 to 30 minutes a day may act as a libido enhancer and certainly will improve your overall health. "Exercising improves blood flow to all areas of your body and that includes the pelvic region where the blood vessels needed for sexual functioning are located," says Feloney. Some other ways that regular exercise can improve your sexual performance include building up your stamina, lowering your blood pressure, relieving stress, and helping you look and feel better.


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).[174] Research on the action of testosterone received a brief boost in 1889, when the Harvard professor Charles-Édouard Brown-Séquard (1817–1894), then in Paris, self-injected subcutaneously a "rejuvenating elixir" consisting of an extract of dog and guinea pig testicle. He reported in The Lancet that his vigor and feeling of well-being were markedly restored but the effects were transient,[175] and Brown-Séquard's hopes for the compound were dashed. Suffering the ridicule of his colleagues, he abandoned his work on the mechanisms and effects of androgens in human beings.
A larger national study, the National Health and Social Life Survey, looked at sexual function in men and women.4 This study surveyed 1,410 men aged 18 to 59 and also documented an increase in ED with age. Additionally, the study found a decrease in sexual desire with increasing age. Men in the oldest cohort (50 to 59) were more than 3 times as likely to experience erection problems and to report low sexual desire compared with men 18 to 29. Experience of sexual dysfunction was more likely among men in poor physical and emotional health. The study also concluded that sexual dysfunction is an important public health concern and that emotional issues are likely to contribute to the experience sexual dysfunction.
The chemical synthesis of testosterone from cholesterol was achieved in August that year by Butenandt and Hanisch.[180] Only a week later, the Ciba group in Zurich, Leopold Ruzicka (1887–1976) and A. Wettstein, published their synthesis of testosterone.[181] These independent partial syntheses of testosterone from a cholesterol base earned both Butenandt and Ruzicka the joint 1939 Nobel Prize in Chemistry.[179][182] Testosterone was identified as 17β-hydroxyandrost-4-en-3-one (C19H28O2), a solid polycyclic alcohol with a hydroxyl group at the 17th carbon atom. This also made it obvious that additional modifications on the synthesized testosterone could be made, i.e., esterification and alkylation.

Overall, it seems that both estrogen and testosterone are important for normal bone growth and maintenance. Deficiency or failure of action of the sex hormones is associated with osteoporosis and minimal trauma fractures. Estrogen in males is produced via metabolism of testosterone by aromatase and it is therefore important that androgens used for the treatment of hypogonadism be amenable to the action of aromatase to yield maximal positive effects on bone. There is data showing that testosterone treatment increases bone mineral density in aging males but that these benefits are confined to hypogonadal men. The magnitude of this improvement is greater in the spine than in the hip and further studies are warranted to confirm or refute any differential effects of testosterone at these important sites. Improvements seen in randomized controlled trials to date may underestimate true positive effects due to relatively short duration and/or baseline characteristics of the patients involved. There is no data as yet to confirm that the improvement in bone density with testosterone treatment reduces fractures in men and this is an important area for future study.


A common and important cause of ED is vasculogenic. Many men with ED have comorbid conditions such as hyperlipidemia, hypercholesterolemia, tobacco abuse, diabetes mellitus, or coronary artery disease (CAD). [6] The Princeton III Consensus recommends screening men who present with ED for cardiovascular risk factors; ED may be the earliest presentation of atherosclerosis and vascular disease. [7]
Currently available testosterone preparations in common use include intramuscular injections, subcutaneous pellets, buccal tablets, transdermal gels and patches (see Table 2). Oral testosterone is not widely used. Unmodified testosterone taken orally is largely subject to first-pass metabolism by the liver. Oral doses 100 fold greater than physiological testosterone production can be given to achieve adequate serum levels. Methyl testosterone esters have been associated with hepatotoxicity. There has been some use of testosterone undecanoate, which is an esterified derivative of testosterone that is absorbed via the lymphatic system and bypasses the liver. Unfortunately, it produces unpredictable testosterone levels and increases testosterone levels for only a short period after each oral dose (Schurmeyer et al 1983).
Osteoporosis refers to pathological loss of bone density and strength. It is an important condition due to its prevalence and association with bone fractures; most commonly of the hip, vertebra and forearm. Men are relatively protected from the development of osteoporosis by a higher peak bone mass compared with women (Campion and Maricic 2003). Furthermore, women lose bone at an accelerated rate immediately following the menopause. Nevertheless, men start to lose bone mass during early adult life and experience an increase in the rate of bone loss with age (Scopacasa et al 2002). Women of a given age have a higher prevalence of osteoporosis in comparison to men but the prevalence increases with age in both sexes. As a result, men have a lower incidence of osteoporotic fractures than women of a given age but the gap between the sexes narrows with advancing age (Chang et al 2004) and there is evidence that hip fractures in men are associated with greater mortality than in women (Campion and Maricic 2003).
"One of the reasons erectile dysfunction increases with age is that the diseases that lead to it also increase with age," notes Dr. Feloney. Evaluating the causes of erectile dysfunction starts with your doctor taking a good health history and giving you a physical exam. Common medical issues that can lead to erectile dysfunction include diabetes, high blood pressure, hardening of the arteries, low testosterone, and neurological disease. Talk to your doctor about better managing these health conditions.
If a trial of oral therapy and withdrawal of offending medications do not restore erectile function or if a patient has medical or financial contraindications to pharmacologic therapy, most primary care practitioners should consider referring the patient to a specialist for additional evaluation and discussion of alternative treatment options. However, some primary care practitioners may recommend vacuum constriction devices.
A vacuum erection device helps draw blood into the penis by applying negative pressure. This type of device is sometimes referred to as penis pump and may be used just prior to sexual intercourse. Several types of FDA approved vacuum therapy devices are available under prescription. When pharmacological methods fail, a purpose-designed external vacuum pump can be used to attain erection, with a separate compression ring fitted to the base of the penis to maintain it. These pumps should be distinguished from other penis pumps (supplied without compression rings) which, rather than being used for temporary treatment of impotence, are claimed to increase penis length if used frequently, or vibrate as an aid to masturbation. More drastically, inflatable or rigid penile implants may be fitted surgically.
In males, testosterone is required for the development of male sex organs such as increased penis and testes size. The hormone also promotes the development of sexual male characteristics during puberty such as voice deepening and the growth of armpit, chest and pubic hair. Testosterone plays an important role in maintaining sex drive, sperm production, muscle strength and bone mass. A healthy level of testosterone is also protective against bone disorders such as osteoporosis.
Effective treatment for erectile dysfunction is available, and for most men will allow the return to a fulfilling sex life. The side effects of the treatment for erectile dysfunction vary depending on the treatment that is used. Some may interrupt the spontaneity of sexual activity. For example, PDE-5 inhibitors typically need to be taken one hour before sex. Side effects may include headaches, indigestion, vasodilation, diarrhoea and blue tinge to vision. Other treatments such as penile injections may cause pain at the injection site, or an erection that will not go down. Treatment options need to be carefully discussed with your doctor to determine which one is best suited to you.
Epidemiological studies have also assessed links between serum testosterone and non-coronary atherosclerosis. A study of over 1000 people aged 55 years and over found an inverse correlation between serum total and bioavailable testosterone and the amount of aortic atherosclerosis in men, as assessed by radiological methods (Hak et al 2002). Increased intima-media thickness (IMT) is an early sign of atherosclerosis and has also been shown to predict cardiovascular mortality (Murakami et al 2005). Cross-sectional studies have found that testosterone levels are negatively correlated with carotid IMT in independently living men aged 74–93 years (van den Beld et al 2003), diabetic men (Fukui et al 2003) and young obese men (De Pergola et al 2003). A 4-year follow up study of the latter population showed that free testosterone was also inversely correlated with the rate of increase of IMT (Muller et al 2004).
"One of the reasons erectile dysfunction increases with age is that the diseases that lead to it also increase with age," notes Dr. Feloney. Evaluating the causes of erectile dysfunction starts with your doctor taking a good health history and giving you a physical exam. Common medical issues that can lead to erectile dysfunction include diabetes, high blood pressure, hardening of the arteries, low testosterone, and neurological disease. Talk to your doctor about better managing these health conditions.

Erectile dysfunction is known to be associated with general health status, thus, lifestyle modification improves erectile function and decreases the rate of decline of function with aging. One year after discontinuation of smoking, patients were found to have a 25% improvement in erectile quality.16 In addition, multivariate analysis found obesity is associated with erectile dysfunction with an approximately 50% increase in ED in obese men as compared with normal weight men.17
Qaseem, A., Snow, V., Denberg, T. D., Casey, D. E., Forciea, M. A., Owens, D. K., & Shekelle, P. (2009). Hormonal testing and pharmacologic treatment of erectile dysfunction: A clinical practice guideline from the American College of Physicians. Annals of internal medicine, 151(9), 639-649. Retrieved from http://annals.org/aim/article/745155/hormonal-testing-pharmacologic-treatment-erectile-dysfunction-clinical-practice-guideline-from
Testosterone begins with cholesterol. In fact, every single sex hormone you make you synthesize from cholesterol – that’s one reason a “heart healthy” low-fat, low-cholesterol diet limits your performance. Fat and cholesterol don’t make you fat. They give your body the building blocks to create abundant testosterone and other sex hormones, which actually makes you lose weight and build muscle, especially if your current testosterone levels are low [1].
In a prospective, multicenter, single-armed study of ED patients who exhibited a suboptimal response to PDE5 inhibitors, the investigators found that percutaneous implantation of zotarolimus-eluting stents in focal atherosclerotic lesions was both safe and feasible and was associated with clinically meaningful improvement on subjective and objective measures of erectile function. [3]
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Erectile dysfunction is the inability to develop or maintain an erection that is rigid enough to allow penetration of the vagina, and therefore functional sexual intercourse. Generally, the term erectile dysfunction is applied if this occurs frequently (75% of the time) over a significant period if time (several weeks to months). If this is the case, the term impotence may also be used.
Erectile dysfunction (ED) is the inability to get and keep an erection firm enough for sexual intercourse. Estimates suggest that one of every 10 men will suffer from ED at some point during his lifetime. It is important to understand that in most cases, ED is a symptom of another, underlying problem. ED is not considered normal at any age, and may be associated with other problems that interfere with sexual intercourse, such as lack of desire and problems with orgasm and ejaculation.
There are treatments available to help you to get and maintain an erection. In addition, making healthy changes to your lifestyle could help with impotence. Switching to a healthier balanced diet, taking more exercise and cutting down on or giving up alcohol and cigarettes could help you to see an improvement in sexual function. If you think that the problem may be related to stress or anxiety, counselling can also help.

The effect excess testosterone has on the body depends on both age and sex. It is unlikely that adult men will develop a disorder in which they produce too much testosterone and it is often difficult to spot that an adult male has too much testosterone. More obviously, young children with too much testosterone may enter a false growth spurt and show signs of early puberty and young girls may experience abnormal changes to their genitalia. In both males and females, too much testosterone can lead to precocious puberty and result in infertility. 
Clinical trials of the effect of testosterone on glucose metabolism in men have occurred in diabetic and non-diabetic populations. Data specific to aging males is not available. A series of studies investigated the effects of testosterone or dihydrotestosterone given for 6 weeks or 3 months to middle aged, non-diabetic obese men (Marin, Holmang et al 1992; Marin, Krotkiewski et al 1992; Marin et al 1993). It was found that physiological treatment doses led to improved insulin resistance, as measured by the gold standard technique using a euglycemic clamp and/or serum glucose and insulin responses during glucose tolerance test. These improvements were associated with decreased central obesity, measured by computered tomography (CT) or waist-hip ratio, without reduced total fat mass. Insulin resistance improved more with testosterone than dihydrotestosterone treatment and beneficial effects were greater in men with lower baseline testosterone levels. Increasing testosterone levels into the supraphysiological range lead to decreased glucose tolerance.

It may also become a treatment for anemia, bone density and strength problems. In a 2017 study published in the journal of the American Medical Association (JAMA), testosterone treatments corrected anemia in older men with low testosterone levels better than a placebo. Another 2017 study published in JAMA found that older men with low testosterone had increased bone strength and density after treatment when compared with a placebo. 

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