Early Estrogen Loss Increases Cardiovascular Risk in Women

Tara Haelle

October 26, 2022

The relationship between estrogen levels and heart health makes it particularly important for clinicians to be aware of those patients who might be at risk for cardiovascular disease despite not having other traditional risk factors, according to a presentation Oct. 12 at the North American Menopause Society annual meeting in Atlanta.

"Endogenous estrogens are protective for cardiovascular disease in premenopausal women," Chrisandra L. Shufelt, MD, chair of the division of general internal medicine and associate director of the Women's Health Research Center at Mayo Clinic in Jacksonville, Fla., told attendees. Yet, "a substantial population of young women are dying prematurely from cardiovascular disease," with rates of cardiovascular death increasing in women aged 35-44 even as rates have decreased in postmenopausal women and in men. One potential reason may be premature estrogen loss.

Shufelt reminded attendees of four major causes of premature estrogen loss: Natural premature menopause, surgical menopause, chemotherapy-induced menopause, and premature ovarian insufficiency. But she would go on to discuss a less widely recognized condition, functional hypothalamic amenorrhea, that also may be contributing to increased cardiovascular risk.

First, Shufelt reviewed the evidence supporting the relationship between estrogen and cardiovascular health, starting with the Framingham study's findings that cardiovascular disease is approximately two to four times more common in postmenopausal women than in premenopausal women, depending on the age range.

"Menopause at an early age, particularly under the age of 40, matters," Shufelt said. "So we should be discussing this with our patients."

Surgical menopause makes a difference to cardiovascular health as well, she said. In women under age 35, for example, the risk of a nonfatal heart attack in those with a bilateral oophorectomy was 7.7 times greater than in women who retained both ovaries and their uterus, and 1.5 times greater in women who had a hysterectomy without bilateral oophorectomy.

In a 2019 study, surgical premature menopause was associated with an 87% increased risk of heart disease even after researchers accounted for age, cardiovascular risk factors, and some forms of hormone therapy. The increased risk from natural premature menopause, on the other hand, was lower – a 36% increased risk of heart disease – compared with those producing endogenous hormones. Although randomized controlled trials are unavailable and unlikely to be done, the Nurses' Health Study and the Danish Nurses Cohort Study, both observational studies, found that heart disease risk was diminished in those taking hormone therapy after surgical premature menopause.

Recommendations for premature or early menopause, from a wide range of different medical societies including NAMS, are that women without contraindications be given estrogen-based hormone therapy until the average age of natural menopause. Though not included in the same guidance, research has also shown that estrogen after oophorectomy does not increase the risk of breast cancer in women with a BRCA1 mutation, Shufelt said. Hormone therapy for premature or early menopause should adequately replace the levels women have lost and that means younger menopausal women often need higher doses than what older women receive, such as 2 mg/day of oral estradiol rather than the standard doses of 0.5 or 1 mg/day.

Functional Hypothalamic Amenorrhea and Cardiovascular Risk

Shufelt then discussed functional hypothalamic amenorrhea (hypogonadotropic hypogonadism), a common type of secondary amenorrhea that affects at least 1.4 million U.S. women. Diagnosis includes lack of a period for at least 3 months in someone who previously menstruated plus lab values below 50 pg/mL for estradiol, below 10 mIU/L for follicle stimulating hormone, and below 10 mIU/L for luteinizing hormone. Causes of this reversible form of infertility can include stress, overexercising, undereating, or some combination of these, plus an underlying genetic predisposition.

"After ruling out polycystic ovary syndrome, prolactinoma, and thyroid dysfunction, clinicians need to consider the diagnosis of hypothalamic amenorrhea," Shufelt said. This condition goes beyond low estrogen levels: Women have elevated cortisol, low thyroid levels, low leptin levels, and increased ghrelin.

"This is not going away," Shufelt said, sharing data on stress levels among U.S. adults, particularly Gen Z and millennial adults, noting that the ongoing "national mental health crisis" may be contributing to functional hypothalamic amenorrhea.

A 2020 substudy from the Nurses' Health Study II found an increased risk of premature death in those who didn't have a period or always had irregular periods starting as early as 14-17 years old. The increased risk of premature death rose with age in those with irregular or absent cycles – a 37% higher risk in 18- to 22-year-olds and a 39% increased risk in 29- to 46-year-olds.

But clinicians aren't adequately identifying the "phenotype of the hypothalamic women," Shufelt said, despite research showing overlap between hypothalamic amenorrhea and a higher risk of cardiovascular disease. Hypothalamic amenorrhea is so understudied that the last original research on the topic was in 2008, Shufelt said in an interview. "No research except mine has been done to evaluate heart health in these young women," she said.

Shufelt described a study she led involving 30 women with functional hypothalamic amenorrhea, 29 women with normal menstrual cycles, and 30 women who were recently menopausal and not on hormone therapy. The women with hypothalamic amenorrhea had average stress levels but their depression scores were higher than those of the other two groups.

The results showed that women with hypothalamic amenorrhea had lower estradiol and leptin levels and higher testosterone levels compared with the control group, and they had higher cortisol levels than those of both groups. Despite having similar body mass indexes as the control and menopausal groups, women with hypothalamic amenorrhea had lower blood pressure than that of the other two groups, yet they had higher cholesterol levels than those of the control group. EndoPAT© (Itamar Medical) testing showed that they had poor vascular function.

"In fact, one-third of the women [with hypothalamic amenorrhea] entered the trial with a diagnosis of what would be considered endothelial dysfunction," Shufelt said. "Our results demonstrated significantly higher circulating levels of serum proinflammatory cytokines in the women with hypothalamic amenorrhea compared to eumenorrheic controls."

Shufelt's team then tested whether giving estradiol to the women with hypothalamic amenorrhea for 12 weeks would improve their vascular health, but they saw no significant differences between the women who received estrogen and those who received placebo.

"Endothelial function is partly mediated by estrogen, and it was expected that giving back estrogen would 'fix' the endothelium, but that is not what happened," Nanette Santoro, MD, professor and chair of obstetrics and gynecology at the University of Colorado at Denver, Aurora, said in interview. "The mechanisms that maintain vascular function in women are not limited to hormones," said Santoro, who was not involved in Shufelt's study but attended her lecture. "We need to think beyond the simple model of estrogen-good, no-estrogen-bad."

Santoro noted how easy it is to overlook the women who may have cardiovascular risk because of hypothalamic amenorrhea.

"Because many women with functional hypothalamic amenorrhea are super athletic and do not have the typical features of people with cardiometabolic disease – such as glucose intolerance, obesity, abnormal cholesterol or triglycerides, or high blood pressure – clinicians tend to think of them as healthy and to think that simply giving back hormones will fix the problems with bone density and vascular function, but that is not enough," Santoro said. "The cognitive-behavioral therapy model for treatment of women with functional hypothalamic amenorrhea addresses the stress-related factors that drive the disorder, and this needs to be considered the standard of care for treatment."

Stephanie S. Faubion, MD, professor of medicine and director of Mayo Clinic's Center for Women's Health in Jacksonville, Fla., who was not involved in Shufelt's presentation, also emphasized the importance of recognizing functional hypothalamic amenorrhea.

"This is an underrecognized entity to begin with, and the fact that these women appear to be at increased risk for vascular dysfunction and potentially increased risk for cardiovascular disease down the road makes it even more important for clinicians to identify them and provide interventions early on," Faubion said in an interview. "These women need to be identified and the etiology of the amenorrhea addressed, whether it relates to overexercising, being underweight, or experiencing significant stressors that have led to the loss of menstrual cycles."

Shufelt's research was funded by the National Institutes of Health. She had no disclosures. Santoro is a member of the scientific advisory board for Astellas, Menogenix, Amazon Ember, and Que Oncology, and she consults for Ansh Labs. Faubion had no disclosures.

This article originally appeared on MDedge.com, part of the Medscape Professional Network.


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