Menopause Ups Lean Women's Asthma Risk

When they reach menopause, lean women have a fourfold
higher risk of asthma
than heavier, but not obese, women who are still menstruating.

The surprising finding comes from a multination European study of 1,274
women age 45 to 56. About a third of the women had reached menopause; none was
taking hormone therapy for menopausal symptoms.

Earlier studies have found no link between menopause and asthma or
respiratory problems. But those studies did not take women's weight into
account, note Francisco Gomez Real, MD, of Norway's Haukeland University
Hospital, and colleagues.

The researchers stratified the women according to their body mass index or
BMI -- a measure of weight adjusted for height. Those with a BMI of less than
23 had a fourfold higher risk of asthma
symptoms . The normal BMI range is 18.5 to 24.9; the overweight range is 25
to 29.9, and a BMI of 30 or more indicates obesity .

Obese women, too, were at somewhat higher risk of asthma symptoms when they
entered menopause.

"Women undergoing the menopausal transition might be at risk of
deteriorating lung health," Gomez Real and colleagues suggest. "This
applies to lean women and, to some extent, to obese women."

Women with a BMI between 23 and 28 appear to have the lowest risk of asthma
when they go through menopause.

Why asthma at menopause? That's
not clear. Gomez Real and colleagues suggest that declining estrogen levels
increase insulin resistance, which in turn increases risk of lung inflammation.
As fat tissue produces estrogen, the leanest women would be at the highest
risk.

Despite the estrogen production
from their extra fat, obesity itself increases insulin resistance. So obesity,
the researchers suggest, cancels out the extra protection afforded by extra
estrogen production by fat cells.

Gomez Real and colleagues report their findings in an in-press issue of the
Journal of Allergy and Clinical Immunology, published online Oct. 29,
2007.

By Daniel DeNoon
Reviewed by Louise Chang
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