“Our aim is to restore [hormone] levels to normal,” says one doctor.

If Ponce de León were alive today, he might be rubbing testosterone gel on himself and picking up an estrogen prescription for his wife. After all, for some people, hormone replacement therapy is today’s fountain of youth. For both genders, it can boost mood, libido, and bone mass.

Of course, not everyone in midlife should head to the pharmacy—and, as with any new medical regimen, people should embark on hormone therapy only after consulting with their doctors. Still, research continues to uncover the benefits of boosting low hormone levels while also finding better ways to administer those treatments.

Women

In the United States, women typically go through menopause at 51. As a woman approaches that age, her estrogen levels plummet to less than a tenth of what they were when she was younger and ovulating regularly, says Barbara Soltes, a gynecologist and reproductive endocrinologist who directs women’s health research at Rush University Medical Center. As a result, women can experience hot flashes, vaginal dryness, moodiness, and trouble sleeping. But for many, hormone therapy can provide a “soft landing into menopause,” says Linda Van Horn, a professor of preventive medicine at Northwestern University’s Feinberg School of Medicine and a principal investigator for the Women’s Health Initiative, which is funded by the National Institutes of Health.

Almost a decade ago, hormone therapy got a bad name when the WHI reported an increase in breast cancer and heart disease among women who took an oral combination of estrogen and progesterone. But the subjects tracked for that study were many years past menopause—on average, age 63—and they were taking more than twice the amount of oral estrogen that Soltes and other Chicago doctors now prescribe. With the lower dose, patients are less likely to experience bloating, breast tenderness, and water retention, says Soltes. (Women who have not had hysterectomies will still need to combine estrogen with progesterone to prevent uterine cancer. And doctors usually advise women to avoid hormone therapy if they smoke or have had breast cancer, a stroke, a heart attack, or blood clots.)

Today’s patients can choose from many forms of treatment: a pill, a gel, a patch, or a vaginal ring. “That’s the beauty of 2011,” says Soltes. “We have lots of options.” And there may be even more. Doctors at the University of Illinois at Chicago are looking at the effect of soy on menopausal symptoms. Women who are beginning to experience changes in their menstrual cycle as they enter menopause can sign up for the study—called RISE, for Research Investigation of Soy and Estrogen—by calling 312-355-5652.

Typically women stay on hormone therapy for about five years. By then, says Soltes, “the body has had a chance to adjust to the low levels of hormones.” But Sharon Green, the executive director of the Institute for Women’s Health Research at Feinberg, has taken hormones for the past 25 years. Now 66, she has tried to go off them, only to have her symptoms return. “Basically I don’t sleep because of hot flashes,” she says.

Each individual is different, so Green and her team are creating an online tool to help women look at their symptoms, their lifestyle, and their family history of breast cancer, heart disease, and bone loss as they decide whether they want to undergo hormone therapy. “The hard thing is, how do we measure what you value in your quality of life?” asks Green. “How much risk [are you] willing to take to feel good and function well?” For example, women need to consider how much they care about an active sex life. Estrogen can boost libido in postmenopausal women—perhaps partly by improving vaginal secretions and tone and making intercourse less painful, says Catherine Stika, associate professor of obstetrics and gynecology at Feinberg.

Other women are motivated to try hormone therapy because of hot flashes, which can cause more than just discomfort. Working with her colleagues at the University of Illinois at Chicago, Pauline Maki, a professor of psychiatry and psychology and the director of women’s mental health research at the school, has found that memory performance declines among women experiencing hot flashes. Maki and other researchers hope that in the future women will be able to take estrogen (which seems to be good for cognition) without progesterone (not so good) by pairing it with a selective estrogen receptor modulator.

Studies indicate that women do not seem to benefit from hormones when they start to take them late in life. “The women we’re discouraging [in regard to] hormone therapy are those who are further from menopause,” says Emily Szmuilowicz, an endocrinologist at Feinberg.

Men

About one in six men of all ages suffer from low testosterone levels—and the problem gets worse over time. “We all know that women’s estrogen declines during menopause, but not as many people appreciate that men’s testosterone drops significantly as they age,” says Craig Niederberger, head of the Department of Urology at the University of Illinois at Chicago’s College of Medicine and coeditor in chief of the journal Fertility and Sterility.

Beginning in their late 30s or early 40s, men see a decline in testosterone of 1 to 2 percent a year, says Robert Brannigan, associate professor of urology at Feinberg. If their levels are too low, men can become depressed and irritable, and they are less able to get and maintain erections. “The goal of therapy is not to shoot to such a high level [of testosterone] that we give patients traits of being really aggressive or hypermuscular,” says Brannigan. “Our aim is simply to restore levels to normal.”

In the past, men who wanted extra testosterone relied on injections. But in 2000, Abbott Laboratories introduced AndroGel, a rub-on product, and in May of this year, the local pharmaceutical giant added a low-dose option. Gels are more convenient than shots, but they can be messy. Today testosterone also comes in patches and in pellets, which are implanted in the buttocks.

At Feinberg, Mark Molitch, a professor of endocrinology, is part of an NIH trial involving 800 men older than 65 to see how testosterone affects muscle strength, memory, and erections, among other things. Muscle and bone weakness resulting from decreased testosterone can increase the risk of falls and broken bones. “If we can ultimately decrease hip fractures, that’s a big deal,” says Molitch. (Men over 65 who think they may have low testosterone and want to enroll in the study can call 877-300-3065 or e-mail t-trial@northwestern.edu; half of the participants will get a testosterone gel, and the other half will get a placebo.)

Men who still want to become fathers should forgo hormone therapy. When the pituitary detects a surfeit of testosterone, it stops producing more. So would-be dads should lay off the injections, gels, and patches. “That’s the last thing you’d want to give them,” says Brannigan.

The bottom line: Men taking testosterone need to regularly talk with their doctors, particularly if they get undesirable side effects such as acne or higher cholesterol levels. They also need to remember that lifestyle makes a difference. Alcohol abuse can lead to a decrease in testosterone and sperm production, so reducing alcohol consumption could make hormone therapy unnecessary.

Hormone replacement therapy is not for everyone. But women with low estrogen levels and men with low testosterone levels should not dismiss those therapies simply out of embarrassment or fear. “It depends on what you think and how you feel,” says Szmuilowicz. “There’s often no easy answer.”

Illustration: Carl Wiens