Progesterone safe for hot fl ashes, B. C. study says

Hormone alone does not appear to increase risk of heart attack or other diseases, as was previously believed

More than a decade after a bombshell study frightened women off hormone replacement therapy, Canadian researchers say fears over one of those hormones — progesterone — have been overblown.

A new short- term study by the University of B. C. and Vancouver Coastal Health suggests progesterone alone does not appear to increase the risk of heart attack or other diseases of the blood vessels when used for hot flashes and night sweats.

The finding comes 12 years after the landmark Women’s Health Initiative Trial reported that a combination regimen of estrogen plus progestin, a synthetic form of progesterone, heightened the risk of heart attack, breast cancer and stroke in women.

“Progesterone began to be blamed for heart attack risks because estrogen was understood to be so good,” said Dr. Jerilynn Prior, a professor of endocrinology at the University of B. C. and head of the Centre for Menstrual Cycle and Ovulation Research. “That was just the mindset.”

Hormone use plummeted. Many women were told to go off hormones and use fans or face cloths for hot flashes instead.

But when researchers took a second look at the data in 2007 a different picture emerged: The risk of heart disease was higher in women who were 20 or more years past menopause, while younger women ( 50 to 59), or women who began taking hormones within the first 10 years of menopause, had a lower risk of coronary heart disease.

In 2009, an expert panel of the Society of Obstetricians and Gynaecologists of Canada concluded hormones are a safe option for moderate to severe symptoms if started early and used only over the short term, meaning four to five years.

Estrogen is the main treatment for hot flashes, but Prior is convinced progesterone is a safer alternative. “Estrogen, over the longer term, increases the risk for heart attack,” Prior said.

“We’re suggesting progesterone probably doesn’t.”

As well, “the message to women taking estrogen is you can’t take it for very long — three, maybe four years. But the average duration of hot flushes is more like eight to 10 years,” Prior said. “So women are caught having to stop the estrogen that helped them and not having an alternative.”

The new study involved 133 healthy, post- menopausal women who were recruited into the trial from 2003 to 2009. The women were randomly assigned to receive either 300 mg daily of progesterone at bedtime, or a placebo, for three months. The women, who were in their mid- 50s, had no known history of diabetes, high blood pressure or heart disease.

The researchers looked at any changes in heart rate, weight, waist circumference, blood pressure, blood clotting, inflammation, cholesterol, blood fats and endothelial function — the thin layer of cells that line the surface of blood vessels and that regulate blood flow — that could increase a woman’s cardiovascular risk.

“We know that endothelial function becomes abnormal very early in people at risk for heart disease,” Prior said. “It’s a fundamental aspect of heart disease.”

After three months, the researchers found no differences in any of the markers for cardiovascular risk between the women on progesterone and the placebo group. They did see an improvement in endothelial function in women taking progesterone, but it didn’t reach statistical significance.

“There were otherwise no differences from placebo,” Prior said.

“The simple, practical implication is that women can take progesterone to treat hot flashes without worrying that it will increase their risk for heart attack,” Prior said.

In Canada, a record number of women are entering menopause as the youngest members of the “baby boom” generation turn 50.

The progesterone study was small and lasted only 12 weeks.

But studies of estrogen alone showed some of the women gained weight or had blood clotting soon after starting the hormone. “Our data don’t show these things, suggesting progesterone is probably safer,” Prior said.

“We’re pretty clear that it doesn’t increase blood clots, which is the big thing that estrogen does.”

In addition to easing hot flashes and sweats, progesterone improves deep sleep, Prior said. However, it’s expensive, costing about $ 3 a day.

Non- drug strategies can help, Prior said. “Anything that decreases stress and our responses to it will decrease hot flushes,” she said.