FRIDAY, Nov. 13 (HealthDay News) -- Women with asthma may notice that their asthma symptoms get worse at certain times of the month. Now, a new study confirms that fluctuating female hormone levels appear to affect airway inflammation, but oral contraceptives might help ease those changes.
In women who were not using birth control pills, the study found that increased levels of estrogen were associated with decreased levels of exhaled nitric oxide -- indicating decreased airway inflammation. In these same women, increased levels of progesterone were associated with increased levels of exhaled nitric oxide, indicating increased airway inflammation.
However, birth control pills lessen dramatic hormone fluctuations, and researchers didn't find differences in asthma symptoms throughout the month for women who took them.
"This study is a first step in looking at the relationship between hormones and asthma," said the study's lead author, Dr. Piush Mandhane, an assistant professor of pediatric pulmonology at the University of Alberta in Canada. The findings might be of use in managing asthma among premenopausal women, the researchers said.
"Among women not on oral contraceptives, we did have changes in exhaled nitric oxide that were related to estrogen and progesterone levels. We didn't have an association with estrogen and progesterone in women on oral contraceptives," said Mandhane.
Results of the study are published in the November issue of the journal Chest.
Mandhane said that because many women report a change in asthma symptoms related to menstrual cycles, it's often assumed that there is an association. But, he said, the relationship between hormonal fluctuations and asthma symptoms hasn't been well-studied.
The current study included 17 women. Eight were on birth control pills that contained estrogen and progesterone. The average age of the women using oral contraceptives was 25.5, while the average age of the women not taking birth control pills was 37.5.
Three of the women in the group not on birth control reported experiencing menstrual-cycle related asthma prior to the study, while just one woman in the birth control group did.
The researchers gathered daily information about symptoms and conducted blood tests to measure estrogen and progesterone levels, performed spirometry (a lung function test) and took measurements of exhaled nitric oxide. They also conducted allergy tests, via skin pricks every other day.
They found that women who didn't take birth control pills had an average exhaled nitric oxide level of 48.2 parts per billion (ppb), while those on oral contraceptives had an average level of 27 ppb. In women who weren't taking oral contraceptives, each increase in estrogen levels was associated with a decrease in exhaled nitric oxide, while each increase in progesterone was associated with an increase in exhaled nitric oxide. That means when progesterone levels are elevated (before menstruation), asthma symptoms are likely to be worse.
Progesterone increases also aggravated allergy symptoms, with more severe allergic reactions evident on skin prick tests when progesterone levels were elevated.
The researchers didn't find any statistically significant differences in allergic reactions during the month for women on birth control pills.
Mandhane said that "birth control works by flattening out the fluctuations in hormone levels," and that's likely why there weren't many differences in asthma symptoms for women taking birth control pills.
"Hormones do play a role," said Mandhane, "and women need to be aware that there's a potential relationship between their asthma symptoms and their menstrual cycles."
Dr. Jennifer Appleyard, chief of allergy and immunology at St. John Hospital and Medical Center in Detroit, said that this study "lends credence to the fact that asthma is affected by hormones. This is definitely not something women should just write off. It's not just all in their minds."
But she also pointed out that this was a small study, and that the women in each group were very different from each other. "There were a lot of older women in one group who took more asthma medication. It's not really comparing apples to apples," she said.
Because birth control pills can have some serious side effects, Appleyard said she would not advise someone to go on oral contraceptives just to help their asthma. However, if a woman notices a difference in her symptoms throughout her menstrual cycle, she may want to talk to her doctor about increasing her asthma medications during that particular time in her cycle, she said.
To learn more about asthma, visit the U.S. National Heart, Lung, and Blood Institute.
SOURCE: Piush Mandhane, M.D., Ph.D., assistant professor, pediatric pulmonology, University of Alberta, Canada; Jennifer Appleyard, M.D., chief, allergy and immunology, St. John Hospital and Medical Center, Detroit, Mich.; November 2009, Chest
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