Estrogen levels inversely linked to exercise capacity in cystic fibrosis

The loss of estrogen’s protective role in exercise capacity could contribute to the gender gap in overall health between men and women with cystic fibrosis, a presenter at the North American Cystic Fibrosis Conference suggested.

“In cystic fibrosis, exercise capacity is associated with survival of patients with cystic fibrosis independent of their lung function ... and exercise capacity is a very important prognostic factor to consider when looking at overall health of patients with cystic fibrosis,” Cassandra Derella, of Augusta University, said in her presentation. “We know women with cystic fibrosis have a steeper decline in their pulmonary function and overall survival compared to men with cystic fibrosis, creating what we know as the gender gap in the disease progression in cystic fibrosis.”

This study included 23 women with cystic fibrosis. Derella and colleagues used the Godfrey protocol to measure exercise capacity via peak oxygen uptake and sampled the participants’ blood at the beginning of each visit to measure their circulating estradiol. Seven women returned for a second visit 1 to 4 years later.

“We found a negative relationship suggesting that greater concentrations of estrogen were contributing to a lower exercise capacity at the time of their visit,” Derella said, contrasting this with women without cystic fibrosis in which there appears to be a positive relationship.

She showed that exercise capacity is inversely proportional to circulating estradiol (r = –.603; P = .013) and, in the secondary visits, the change in exercise capacity was inversely proportional to the change in estradiol (r = – .907; P = .034).

“This is suggesting that as an increase in estradiol occurs in women with cystic fibrosis, it’s contributing to a decrease in their exercise capacity. This is extremely important as women age and they develop and go through puberty and have an increase in estrogen and as we continue to use exercise capacity as an important marker of survival in women and men with cystic fibrosis,” Derella said. “This could be why we see this gender gap once puberty onsets in men and women with cystic fibrosis. The loss of estrogen’s beneficial role in exercise could in part explain the gender gap.”