There are many causes of decreased production of testosterone from the testes in men or from the adrenal glands. Some of these include: drugs, radiation, alcohol, chronic obstructive pulmonary disease, renal failure, cancer, cirrhosis of the liver, hemochromatosis, chronic diseases, nutritional deficiencies, genetics, trauma, pituitary tumors, and obesity. Estrogen will fill some of the testosterone receptors in the brain, such that the hypothalamus will send a message to the testes to produce less testosterone.

As we age, our production of Sex Hormone Binding Globulin (SHBG) increases possibly due to the stimulus of extra estrogens that occur. This protein actually binds the testosterone to make it unavailable for its role in stimulating receptor sites around the body. Normally only 2-3% of the testosterone is free from attachment to proteins.

In an area crucial to males - that of sexual function - testosterone replacement has produced results that are very positive: increases in libido and sexual activity. Also, testosterone has been shown to promote increases in bone density and muscle mass, while at the same time bringing about decreases in body fat.

Dr. Eugene Shippen from PA, USA recognizes that the estrogen/free testosterone ratio is the important predictor of male well-being, and thus the method of testosterone replacement is the most important decision to be made to keep the conversion to estrogen at a minimum. If we allow the testosterone levels to peak to enormous non-physiological levels as by testosterone injections, then we are priming our patients for symptom swings, and conversions to the unwanted estrogens.

We generally use methods to slowly increase the levels of testosterone in the serum. We have used Andriol in pill form, as well as the testosterone patch (Androderm or Testoderm) which will gain more popularity and we routinely supply prescriptions for testosterone cream, usually a 5% cream, with 1 cc applied each night to the armpits before bed. We never allow the cream to be applied to the scrotum for fear of conversion to dihydrotestosterone, another hormone that we will discuss.