Harvard psychiatrist, Dr. Susan Bako, titled her book on testosterone replacement in women, The Hormone of Desire. Both the title and the message of Dr. Bako's book expresses an effect of testosterone exuberantly obvious to any testosterone deficient person after only a few days of adequate replacement therapy of this powerful, but largely misunderstood hormone.

Although after fifty years of scientific inquiry, researchers still debate and study the exact mechanisms responsible for sexual arousal and performance, there is no doubt that when testosterone levels drop below a critical point, in man or woman, both interest and action will decline and ultimately cease completely. Testosterone is truly the hormone of sexual desire for both men and women.

Most lay and professional people alike still describe testosterone as, "the male hormone". Testosterone is far and away the most powerful hormone determining male physiology. Men naturally posses in excess of ten times the amount of testosterone found in women. However, testosterone is the most abundant sex hormone in both men and women. In fact, testosterone is the most abundant sex hormone in women. A young woman with optimal hormone levels has, in her blood, about 1,000 times more testosterone, by weight, than estrogen!

Good testosterone levels increase energy and endurance, raise the pain threshold, reduce muscle and joint pains, strengthen the heart and clear the mind. Without adequate testosterone, exercise, even intense exercise, will do little to increase muscle mass and strength or reduce body fat.

I have treated patients, both men and women, who suffered from chest pain diagnosed as angina without typical signs of significant coronary artery occlusion, obtain complete relief from their pain within a few weeks of starting testosterone replacement. I am not suggesting that testosterone is a cure-all for heart disease. However, it does decrease cardiac muscle oxygen demand, increase blood flow to cardiac muscle and both strengthens and increases cardiac muscle mass. These are all parameters which, when they worsen, are involved in angina and ultimately heart attack and heart damage. Testosterone also reduces cholesterol in men. Clearly, even when the symptoms of heart disease are caused by factors other than the ones discussed, replacement therapy can only help, not hurt, recovery.

Testosterone is often the first hormone in women to decline with age. Testosterone deficiency in young men due to stress and other unknown causes is surprisingly common. I do not recommend the routine replacement of testosterone in very young men who present with sudden deficiency symptoms. Often in such cases, all that is needed to regain depressed endocrine function is rest, stress reduction, and an escalating exercise regimen.

Patients start with mild workouts and increase effort slowly to strenuous high intensity levels. The situation of young men with persistently low testosterone levels presents a difficult clinical problem.

Hard physical training is the most potent natural stimulant, aside from actual testosterone replacement, to increase blood levels of testosterone in people of all ages. In older men or women, this response to exercise is not sufficient to produce enough additional testosterone to alleviate deficiency symptoms. When testosterone is replaced in older adults the results are immediate, dramatic and gratifying.