Hailed as a "prescription for passion" by some and condemned as the "rage steroid" by others, testosterone is the most celebrated, feared and misunderstood of all hormones.

Our culture lauds this substance's leading role in male virility and casts it as the villain in acts of violent crime. In truth, testosterone is neither miracle nor monster, but rather, a key player in the complex chemistry of human hormones. When balanced by other hormones, testosterone, also known as androgen, plays a lead role in the health and well-being of both sexes.

These days, many menopausal women are turning to testosterone to provide what estrogen alone cannot—renewed sexual desire. Psychiatrist Dr. Susan Rako believes testosterone therapy is a major breakthrough for midlife women. Understanding that testosterone deficiency may be to blame for a loss of interest in sex in an otherwise happy relationship, she points out, could prevent much unnecessary anguish.

Dr. Rako's book, "The Hormone of Desire: The Truth About Sexuality, Menopause and Testosterone," is one of a growing wave of publications heralding the importance of this hormone to women's health. Although androgen therapy is controversial, several small-scale studies and anecdotal evidence from women and clinicians suggest that individualized dosages provide a number of therapeutic benefits.