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Testosterone is a hormone made by the testes and the adrenal gland that has many effects throughout the body.
Testosterone is important for muscle mass, bone strength, hair growth, and sexual function. Low testosterone can cause symptoms such as low energy, poor concentration, depression, low libido, and erectile dysfunction. Testosterone deficiency is the condition of having low testosterone and 1 or more of these symptoms. Testosterone deficiency is common, affecting approximately 7% of men in their 50s, and increases with age.
In some cases, the testes are not able to make enough testosterone. In other cases, the brain is not making enough luteinizing hormone, which signals the testes to make testosterone. Both can result from infection, trauma, exposure to toxins such as chemotherapy, or genetic conditions. Chronic illnesses such as diabetes, obesity, anemia, and HIV infection are also linked to low testosterone. Certain medications such as opioids, corticosteroids, and anabolic steroids can lead to low testosterone.
When testosterone deficiency is suspected, a man should undergo a medical history and physical examination by either his primary care physician or a specialist. Blood tests to check the morning total testosterone level are typically performed twice to confirm the diagnosis. Other blood or imaging tests may also be necessary.
The standard treatment for testosterone deficiency is testosterone therapy (TT), which comes in formulations such as topical gels, self-injection, and pellets under the skin. These medications should be avoided in men interested in having children, as they can decrease sperm production and fertility.
Men taking TT should be seen regularly by their physician. Side effects of TT can include changes in mood, headache, hair growth, male pattern baldness, breast tenderness, acne, and decreased testicular size. Regular blood tests are necessary to check testosterone levels and blood counts, which can become abnormally high. There is no strong evidence that TT increases risk of blood clots.
Testosterone can affect the prostate, and some men with prostate conditions should not use TT. While TT does not cause prostate cancer, men with untreated prostate cancer or men recently treated for high-risk prostate cancer should avoid TT. Men taking TT should ask their physician about prostate cancer screening. The evidence is not conclusive whether TT can worsen urinary symptoms from an enlarged prostate.
The relationship between testosterone and cardiovascular disease (CVD) is complex. Early studies found that TT may be linked to stroke and heart attack, which led to a warning from the US Food and Drug Administration. However, additional studies showed no link between TT and these events, so it is not known if TT increases risk of stroke or heart attack.
Men with low testosterone are at increased risk of CVD. It is not known whether this risk is due to low testosterone or because men with low testosterone are more likely to have other medical conditions linked to CVD, such as high blood pressure, obesity, and high cholesterol. Further research is needed on the risks and benefits of TT for cardiovascular health.
National Institutes of Healthwww.nih.gov/news-events/nih-research-matters/understanding-how-testosterone-affects-men
Conflict of Interest Disclosures: None reported.
Source: Sargis RM, Davis AM. Evaluation and treatment of male hypogonadism. JAMA. 2018;319(13):1375-1376.
Halpern JA, Brannigan RE. Testosterone Deficiency. JAMA. 2019;322(11):1116. doi:10.1001/jama.2019.9290
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