Estrogens Derived From Horse Urine Linked to Heart Disease Risk

heart disease linked to HRT made with horse urine

A new study that finds higher risks of deep vein thrombosis blood clots in those taking conjugated estrogens for menopause symptoms.

From: By: Jennifer J Brown, PhD

MONDAY, September 30, 2013 — The cardiovascular risk of using estrogen therapy to reduce women’s menopause symptoms like hot flashes and vaginal dryness has often been hotly debated. Adding fuel to the fire is a new study that links conjugated equine estrogen hormone therapy — estrogen derived from the urine of pregnant horses — to a woman’s risk of developing heart disease.

HRT made with horse urine linked to heart disease riskThis risk of taking conjugated equine estrogens was compared to the risks of a second type of hormone therapy, estradiol, in research published today in the clinical journal JAMA Internal Medicine.

Nicholas L Smith, PhD, an epidemiologist from the University of Washington School of Public Health, and other researchers studied the heart health of 384 women who were postmenopausal and taking hormone replacement therapy, HRT. The women were ages 30 to 79, and members of a health maintenance organization in Washington, the Group Health Cooperative.

The investigators found a total of 68 cases of women with deep vein thrombosis — blood clots — and 67 of heart attack, along with another 48 cases of stroke. Which estrogen medications the women had taken were studied, in order to uncover any links to heart disease risk.

Women who used the estrogens that came from horse urine — also know as Premarin — were twice as likely to have venous thrombosis. The women taking conjugated equine estrogen were also slightly more likely to have heart attacks, but risk of stroke did not vary based on which medication was taken.

“Now with this new information we are learning to choose wisely. It seems that different preparations of HRT carry unique risk,” said Stephanie Moore, MD, a cardiologist at the Massachusetts General Hospital (MGH) Institute for Heart, Vascular and Stroke Care’s Heart Failure and Cardiac Transplant Program in Boston. Dr. Moore was not involved with the study.

How Estrogens Affect Heart Health Risks

Taking the analysis a step further, the study investigators compared blood samples from the women by looking at blood factors that lead to clotting. They discovered significantly higher levels of clotting factors in women who took the horse-derived estrogens. This finding provides biochemical evidence for the cardiovascular risk the women experienced, and that may have led to the blood clotting of venous thrombosis.

“When we first started studying the effects of hormone replacement on women’s cardiovascular health,” Dr. Moore said, “the initial thought was that all hormone replacement strategies led to increased heart attack and stroke for all women.” Follow-up studies contested the risks to women’s heart health.

“Over years of follow-up we have learned to individualize treatment and that HRT (hormone replacement therapy) is not necessarily bad for all women,” said Moore. “Actually, it is a small minority that has increased risk of heart attack or stroke with HRT. The majority of women are safe,” she emphasized.

The study authors concluded that more comparative safety investigations like this are needed. They wrote that if their results were confirmed, “The number of avoidable venous and possibly cardiac thrombotic events may be lowered by selecting lower-risk medications.”

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AUTHOR: Amber Barnes
  • Margo Nielsen

    We’ve known this for a long time. In fact, I had a friend who knew it in the 1980’s, but she took it anyway because her symptoms were so severe, and died of a heart attack in 1999 at the age of 59. When I started menopause I went straight to Chinese herbal hormone replacement, with no negative side effects.

    October 1, 2013