Men usually experience a decrease in testosterone from the age of 40. Unlike menopause in women which is defined as a sharp fall in oestrogen, testosterone decreases more gradually (perhaps a rate of 2% from the age of 40) and then continues to fall gradually, rather than plateauing. Men are less likely than women to feel symptoms of hormone decline, but at least 20% of men over 50 do experience symptoms of testosterone deficiency, and many others have probably accepted changes and forgotten how good they used to feel! It is particularly the free testosterone (the testosterone that is not bound up in proteins and therefore biologically available to act) that declines. Testosterone levels need to be adequate to maintain normal sexual function (sexual desire, plus the ability to get and maintain an erection) and to prevent a decline in stamina and muscle mass. Symptoms of low testosterone can cause depression, insomnia, irritability, fatigue, poor concentration and even hot flushes. Age, genetics and lifestyle all play a factor: stress, alcohol, smoking, obesity, lack of exercise, vasectomy and conditions such as diabetes will lower testosterone levels even more. Erectile problems can be an early warning sign of diabetes or cardiovascular disease so if these are a problem it is important to see a doctor and exclude concomitant disease. If low testosterone is identified as the cause of the symptoms, then testosterone therapy is an excellent cure. For erectile problems, testosterone is perhaps a more holistic option than other standard treatments such as Viagra, which gets the blood supply to the right place but doesn't necessarily restore mood, well-being or desire. Testosterone can be given in combination with other treatments like Viagra, but testosterone is about more than sexual function: many men on testosterone replacement therapy describe it as giving them their life back because of testosterone’s role in sleep, mood and energy. Like hormones for women, testosterone can be expected to have a number of health benefits for men.
There are over 40 years of well-designed, randomized controlled trials and observational studies that all support the safety and efficacy of testosterone administration. These studies demonstrate that low endogenous levels of testosterone are associated with an increased risk of cardiovascular disease and heart attacks. Testosterone has been shown to prevent plaque deposition (atherosclerosis) which is the primary cause of heart attacks. Testosterone also helps prevent lower urinary tract symptoms and prevents against osteoporosis. Higher levels of testosterone are associated with a decreased risk of prostate cancer and less severe types of cancer if one develops a cancer. (In fact low levels of testosterone are associated with a greater risk of prostate cancer and a more severe and aggressive type of prostate cancer.) Some recent studies showed that testosterone treatment decreases morbidity and mortality from all causes, including heart disease and all cancer.
My preferred route for testosterone replacement therapy is by far transdermal - eg a gel applied once every morning to the skin. Transdermal testosterone allows for easy, physiologica dosing. Testosterone injections are more invasive and can cause symptoms to fluctuate between doses depending on the frequency of injections.
Most men stay on testosterone replacement therapy long term because they feel so much better on it and because their own natural levels may continue to decline.
Interesting articles in the press: