Testosterone is a hormone that helps men to maintain male characteristics. Formed in the testes, it affects:
- Sex drive
- Sperm production
- Bone density
- Fat location
- Muscle mass and strength
- Red blood cell production
The range of "normal" testosterone levels varies. The testes of aging men may make less of the hormone than during the teens and early adult years. But a sudden drop-off in production, like women have during menopause, is uncommon.
Though levels decline gradually, a health problem can cause a drop in the hormone. Some changes in older men are wrongly blamed on low testosterone. Erectile dysfunction may be tied to low levels, for instance, but it is often due to problems with blood circulation.
Diagnosing low testosterone (hypogonadism) must be done with caution because levels in each man can vary greatly. There is no standard scale of what symptoms may be caused by specific levels of the hormone. And doctors in other countries can have different standards for low levels.
Along with getting a testosterone level, the medical workup should include psychological and physical assessments. Repeat measuring of morning total testosterone levels may be needed too. This can help rule out variations that may be due to other health problems.
Is more better?
More testosterone is not always better.
Testosterone levels raised through performance-enhancing steroids may cause:
- Liver cancer
- Heart attacks
- Prostate cancer
But low testosterone can also raise risks for:
- Memory loss
- Mood changes
- Heart disease
- Metabolic syndrome
Treating low testosterone
It is not known if raising low testosterone to "normal" levels can help relieve any of these health problems. Replacing the hormone can't fix some things. This includes problems that come with normal aging.
Testosterone therapy has been used in men since the 1940s. If you have a low testosterone level and treatment is suggested, find a doctor who is an expert on the psychological, metabolic and sexual effects of the hormone. Sometimes a three- to six-month test can determine whether a man can be helped by this therapy.
Some claims have been made that testosterone can raise muscle mass, sharpen memory, boost sex drive and improve energy. But none of these are proven.
One study shows testosterone replacement in men with angina or chronic heart failure raises their exercise tolerance. Another study says men ages 40 to 79, who naturally produce higher levels, have lower death rates from many diseases.
But these results are uncertain. Even the study on exercise tolerance noted that the effects trail off after one year. And, there is no proof that replacement therapy improves disease survival rates for those with low testosterone.
Experts say more studies are still needed to understand the role - if any - that testosterone replacement therapy plays in the treatment of many conditions.
Created on 02/15/2001
Updated on 11/20/2008
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- Gooren L, Meryn S, Shabsigh R. The metabolic syndrome: when is testosterone treatment warranted. Journal of Men's Health. 2008;(5S);S40-S45.
- Channer KS. Testosterone and cardiovascular disease. Journal of Men's Health. 2008;(5S):S18-S20.
- 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. Circulation. 2007;(116);2694-2701.