Testosterone, the primary hormone produced by the testicle, promotes most of the masculine characteristics of the body. These ‘secondary sexual characteristics’ include development of the penis, increased muscle strength and mass, facial and body hair and male sexual function. There are many medical conditions in men that result in low testosterone levels, a condition known as hypogonadism. Hypogonadism can cause symptoms such as loss of energy, depression, thinning of the bone (osteoporosis), loss of sexual interest and function and muscle wasting. Men are less likely than women to be evaluated for osteoporosis. Osteoporosis increases the risk of hip fracture which has a mortality rate of 30% during the first year. For that reason screening for low testosterone and associated osteoporosis before a fracture occurs can result in life saving treatment.

Trauma to the testicles such as sports injuries or mumps, tumors of the pituitary gland or simply prolonged and severe illnesses can all cause low testosterone levels. Testosterone levels in men typically decline with aging and by the age of 60 about 20% of men have low testosterone levels. Hypogonadism developing due to aging is sometimes called ‘andropause’. The first challenge for those suffering from a low testosterone level is to have the condition properly diagnosed since symptoms are non-specific and may be attributed to age alone. Diagnosing low testosterone can usually be done with a simple blood test. Doctors disagree about the best test to use for diagnosing low testosterone but in general the total or free testosterone level (not bound to a carrier substance in the blood) or both together, are the most frequently used.

Once a low testosterone level is detected and if there is no reversable cause of this problem then testosterone replacement is generally advised. The use of an injection to administer testosterone has been the most commonly used method until the last decade or so. Testosterone containing patches and gels have been developed that can be applied to the skin. The hormone is then absorbed through the skin into the blood stream. Although testosterone can be taken by mouth this method is not advised due to the risk of liver toxicity.

Among the first preparations designed for skin application was Testoderm which employs a testosterone containing patch applied directly to the testicle. Due to inconvenience and discomfort this product has not been very popular. Another patch is Androderm which can be placed on any area of skin on the body which is free of hair. The adhesive on the patch occasionally causes a skin rash, and the patch itself is cumbersome. Up to one third of individuals using a testosterone patch experience some discomfort.

Avoiding the inconvenience of a patch is Androgel which was approved by the FDA in 1999. Testim is another testosterone gel product. The gel is rubbed directly into the skin every day without the need for a patch. Many men find this the easiest and least irritating of the transdermal preparations of testosterone. Studies have shown high levels of patient satisfaction with gel product. In a study conducted at Duke University researchers found that men with testosterone levels less than 300 ng/dl treated with Androgel (testosterone gel) had significant improvement in sexual function, muscle strength and lean body mass. Overall satisfaction was better with Androgel than with the testosterone patch.

Can testosterone gel be of benefit to women too? Some physicians have used small amounts of testosterone gel applied to the clitoris and labia to improve sex drive and orgasm in women with sexual dysfunction. Controlled studies of testosterone gel used in this manner in women are currently not available although some experts assert that testosterone is beneficial to a woman�s sexual response.

There are several important precautions to follow when using testosterone supplementation. Although testosterone probably does not cause cancer to develop within the prostate, it will promote the growth of prostate cancers that otherwise may have been indolent. For this reason PSA levels should be monitored and the prostate examined regularly in testosterone users. Excessive amounts of testosterone may cause breast enlargement (gynecomastia) due to the body’s conversion of excess testosterone to estrogen. Aggressive behavior may be promoted as well.

Testosterone is a controlled substance which can be obtained by prescription from a licensed physician only. When used appropriately it can make a substantial contribution to the well being of men with hypogonadism.