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Doctors have long known that a sensitivity to salt in the diet can help lead to high blood pressure in some people. Now a new study suggests that hormonal changes following menopause may trigger this salt sensitivity in women previously unaffected by salt.
In fact, researchers say, in a group of younger women undergoing hysterectomy with ovary removal, the number subject to salt sensitivity doubled within four months of the surgery.
"Among women who undergo surgical menopause, there is an increase in their sensitivity to salt, potentially raising their blood pressure," says lead researcher Dr. Ivonne Hernandez Schulman of the Veterans Affairs Medical Center in Miami and the University of Miami's Miller School of Medicine.
The study was presented Friday in Washington at the American Heart Association's annual high-blood-pressure conference. Schulman and her team studied 40 women, averaging 47 years of age, with normal blood pressure and no history of diabetes. All of the women underwent hysterectomy and ovary removal, which induced menopause.
Four months after surgery 21 women were salt-sensitive, the researchers found, compared with only nine women before surgery.
While the women in the study who developed salt sensitivity did not show an increase in blood pressure, Schulman says, other studies indicate that most women don't develop high blood pressure until five to 10 years after menopause.
According to Schulman, some women naturally develop salt sensitivity after menopause and run the risk of developing high blood pressure, which in turn increases risks for cardiovascular disease and stroke.
"About 50 percent of people with high blood pressure are considered to be salt-sensitive," Schulman says. "Even people with a normal blood pressure who are salt-sensitive have a higher risk of developing high blood pressure and possibly cardiovascular disease."
However, Dr. Howard Weintraub, co-director of New York University's Lipid Treatment Program and an associate professor of medicine at the university's School of Medicine, is skeptical of the findings.
"These findings need to be taken with a grain of salt," he says.
Weintraub is concerned that the study didn't take into account the ethnic makeup of the people involved, since different groups have different propensities to salt sensitivity. In addition, Weintraub says, whether or not the women were obese was not mentioned. Either factor could influence the findings.
"Everything we know now about postmenopausal, hypertensive women is that the problem is not salt sensitivity," Weintraub says. "The problem that we are looking at is the impact of women who develop obesity. Salt sensitivity is an added problem that goes on top of preexisting morbidity."
Weintraub is also concerned that this study may send a dangerous message.
"I don't want people thinking that, in a 55-year-old woman, her blood pressure can be adequately handled by just diuretics, which reduce salt," he says.
But Ana Paula Dantas, an assistant professor of medicine in the Division of Nephrology and Hypertension and the Center for the Study of Sex Differences in Health, Aging and Disease at Georgetown University in Washington, believes that the study raises significant questions.
"The observation that a high percentage of women who were salt-resistant before the removal of ovaries became salt-sensitive suggests that salt sensitivity may be partially responsible for the increase in the progression of hypertension after menopause," she says.
This study could not directly associate the increase in salt sensitivity to higher blood pressure in those women, Dantas says, probably due to the short period of observation.
"Even without this correlation," she says, "this study raises important questions: Should postmenopausal women be more concerned about dietary salt intake than men? Would diuretics be more effective in menopausal women than in men?
"This newly revealed effect of ovarian hormones can lead to the development of novel pharmacological and dietary approaches for preventing and treating cardiovascular disease in postmenopausal women."
(The HealthDay Web site is at http://www.HealthDay.com.)
c.2005 HealthDay News