No harm adding a little testosterone.

Adding testosterone to estrogen replacement therapy (ERT) can help women combat postmenopausal mood symptoms such as depression and loss of libido. Now, new research indicates that the male hormone, contrary to some fears, doesn't reduce the established cardiovascular benefits of ERT. Researchers from the Bowman Gray School of Medicine at Wake Forest University in Winston-Salem, N.C., found that postmenopausal macaques treated with estrogen plus testosterone experienced the same degree of protection from heart disease as animals receiving estrogen alone.

Veterinarian Janice D. Wagner reported the results in San Francisco this week at an American College of Obstetricians and Gynecologists meeting. She says the work may significantly "increase the quality of life" of millions of women.

ERT is commonly prescribed to relieve symptoms associated with menopause, such as hot flashes and vaginal dryness. It also helps to prevent osteoporosis and cardiovascular disease.

Despite the benefits, only 10 percent of postmenopausal women use ERT. Wagner says the number one complaint of women getting replacement estrogen is that they "don't feel well." When testosterone is added, Wagner says, women have far fewer complaints.

But estrogen-testosterone formulations are approved only for mood symptoms and hot flashes because of fears that testosterone might undo estrogen's cardiovascular benefits.

The Bowman Gray team tested an estrogen-testosterone formulation in macaques made postmenopausal by removal of their ovaries. The animals provide a good model to test cardiovascular effects of menopause because "they rapidly develop cardiovascular disease after surgery while on a high-fat diet," says veterinarian Michael R. Adams, the group leader.

In his team's study, 12 macaques received estrogen, 12 got estrogen plus testosterone, and 12 served as controls. Monkeys in both treatment groups had one-third to one-sixth the LDL, or "bad" cholesterol, of the control group. And, when the researchers measured enzymes associated with bone loss, the treated groups had 40 percent less bone loss than controls. "The addition of testosterone doesn't negate the positive cardiovascular effects of estrogen," Wagner says. And, because women tolerate estrogen- testosterone better, it is likely that more would use replacement therapy. Wagner hopes human trials will follow.