Testosterone has additional profound metabolic effects. It plays a role in preventing and treating diabetes mellitus. This disease is characterized by high blood sugar because the cells are not able to take in sugar and metabolize it properly. Sugar enters the cells of the body as a result of the action of insulin combining with insulin receptors on the cells. A problem with these insulin receptors may result in a reduction of sugar entering the cells and consequently an increase in blood sugar characteristic of diabetes. Testosterone helps the insulin receptors to work more efficiently, thus reducing the tendency toward diabetes, which increases with age.
Another role of testosterone is to help regulate the immune system. Patients with autoimmune disorders, such as rheumatoid arthritis, systemic lupus erythematosus and multiple sclerosis appear to benefit from testosterone. It has been used to improve appetite, increase weight in malnourished patients, improve wound healing and increase resistance to infection. By building protein, it builds body mass while at the same time reducing obesity. It also seems to lower serum lipids, such as cholesterol and triglycerides and has been used in Europe to treat patients with gangrene of the feet, coronary artery heart disease, high blood pressure, and other cardiovascular diseases. A man’s general motivation, aggression and drive also seem to be related to tissue levels of testosterone.
So, the reduced production of testosterone by the testes with aging may indeed contribute to many of the physical, emotional and mental changes that are seen during this andropausal period. The question then becomes whether or not men may benefit by the administration of natural testosterone in physiologic doses to replace deficient testosterone of andropause. This is directly analogous to the use of natural female hormones, estrogen and progesterone during menopause in women. Furthermore, just as younger women may benefit from the administration of natural female sex hormones if they are deficient for various reasons, so may younger men benefit from the administration of natural testosterone if they are deficient.
What is testosterone and how does it relate to other hormones? Testosterone, like all of the other sex hormones, is chemically a steroid hormone. A steroid is an organic (carbon containing) compound consisting of a four-ring structure. In addition to the sex hormones, estrogen and progesterone, other steroid compounds important to the body are vitamin D, cholesterol, and hormones from the adrenal cortex, including cortisone, hydrocortisone, aldosterone, and DHEA. Cholesterol, that most maligned compound, is the mother of all of these compounds.
Testosterone works directly on many tissues of the body. But, dihydrotestosterone or DHT, a hormone derived from testosterone, is much more potent than testosterone, and acts on the prostate gland and other sexual organs. DHT is produced within the prostate gland and some other organs from testosterone by the enzyme 5-alpha reductase. Without DHT a male would not develop his external sexual organs or his prostate. DHT is necessary for the normal growth and development of the prostate. Its presence is also necessary for the pathologic enlargement of the prostate, known as benign prostatic hyperplasia (or BPH) in older men. Because the presence of DHT is necessary for the development of BPH, a recent therapeutic approach to treating this condition is to reduce the formation of DHT by blocking the enzyme 5-alpha reductase. This can be done by the new, highly promoted drug finasteride (or Proscar), which has been approved by the FDA for this purpose. The herb serenoa repens (or saw palmetto) also has this effect, as one of its actions. What is not discussed in the literature of these 5-alpha reductase inhibitors is that testosterone may be converted to one of two compounds. The first is DHT as we’ve been discussing. The second is estradiol, the female sex hormone. So, a blockage of DHT formation, may lead to an increased level of estradiol via the enzyme aromatase. Increased levels of estrogen may play a role in the development both of prostate cancer and BPH.