Testosterone Levels May Play Part in Uterine Fibroid Risk

Marcia Frellick

December 16, 2015

Elevated testosterone levels may raise women's risk for developing uterine fibroids, new data show.

Jason YY Wong, ScD, of Stanford University School of Medicine, California, and colleagues found that women who have high levels of both testosterone and     estrogen in midlife may face a greater risk of developing the benign tumors than women with low levels of the hormones.

The study was published online December 15 in the    Journal of Clinical Endocrinology & Metabolism.

Testosterone has been considered a predominantly male hormone, and levels are low in women compared with estrogen.

However, "testosterone may have a larger impact than we previously thought," Dr Wong told      Medscape Medical News.

He says it may be prudent for doctors to measure testosterone levels along with other sex hormones, particularly estrogen, when providing treatments that     alter hormone levels in women at midlife. Testosterone levels are currently not routinely checked in the clinic for women in this age range, he noted.

Asked for comment, Dana Redick, MD, director of the University of Virginia Health System's Uterine Fibroid Treatment Center in Charlottesville, who was not     involved in this latest research, noted some limitations of the study.

"It's a small group of women, of which less than half…who started got full follow-up," she told Medscape Medical News, noting also that the women     were asked only if they had been told they had fibroids, not whether the fibroids had caused them problems or required treatment.

Nevertheless, the concept that testosterone may be involved in the development of fibroids is still an important finding, she stressed.

Only Half Women in Study Were Followed Up

By age 50, between 70% and 80% of women develop fibroids, which can cause irregular bleeding, infertility, pelvic pain, repeated pregnancy loss and other     reproductive complications, the authors say. Women who are African American or are overweight face a greater risk of developing uterine fibroids.

Hysterectomy is the first-line treatment; other options are limited and include myomectomy, the surgical removal of individual fibroids leaving the uterus     intact.

Dr Wong and colleagues examined hormone levels and the incidence of uterine fibroids in participants in the    Study of Women's Health Around the Nation (SWAN). Women who had had a hysterectomy were excluded from the study.

Among the 3240 women enrolled at the beginning of the study, however, only 43.6% completed the follow-up visits.

During nearly annual visits, participants had their blood tested for estrogen and androgen levels. In addition, the women were asked whether they had been     diagnosed with or treated for uterine fibroids. They were followed for 13 years.

Of the women, 512 reported having a single incidence of fibroids, and an additional 478 had recurrent fibroids.

Those who had high levels of testosterone were 1.33 times more likely to develop a single incidence of fibroids than women who had low levels of     testosterone (odds ratio [OR], 1.33; P = .04).

And women who had high levels of both testosterone and estrogen faced an even greater risk of fibroids than those with low levels of the hormones (OR,     1.52; P = .02).

However, women with high levels of both hormones were less likely to have a recurrence of fibroids than women with low levels (OR, 0.50; P = .04),     a finding Dr Wong said his team's research could not explain.

"I really can't comment on the mechanism of the disease based on our study, because our study was an observational study based on a real-world population.     It's a question better addressed in a clinical epidemiology study," he said.

He sees the findings as a stepping stone for other prospective studies. In the future, he would like to see women studied over longer terms and checked     more frequently for sex hormone levels.

"We wanted to raise awareness of the potential health impact of testosterone and androgens in midlife women and to provide a starting point for future         population-based studies to consider their levels in the clinic."

But "nuances between many studies would need to be considered before any changes in practice should be made," he added.

Important to Identify How Fibroids Develop and New Treatments

"Our findings are particularly interesting because testosterone was previously unrecognized as a factor in the development of uterine fibroids," added     senior author Jennifer S Lee, MD, PhD, also of Stanford University School of Medicine and Veterans Affairs Palo Alto Health Care System.

"The research opens up new lines of inquiry regarding how fibroids develop and how they are treated," she says in an             Endocrine Society statement.

"Given that managing uterine fibroids costs an estimated $34.4 billion in annual medical expenditures nationwide, it is important to identify new ways to     better treat this common condition."

Dr Redick agrees with Dr Lee: "This is a great window opening up. It's telling us to look at something other than estrogen or progesterone. I think this     has great value. Very few people have looked at a [13-year] window of women with fibroids. It's something I'm going to pay attention to."

The study authors and Dr Redick declared no relevant financial relationships.

J Clin Endocrinol Metab. Published online December 15, 2015. Abstract

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