The effects of estrogen replacement therapy on airway function in postmenopausal, asthmatic women

Background: Data from multiple clinical, epidemiologic, and in vitro studies are conflicting regarding the effect of estrogen replacement therapy (ERT) on airway function in postmenopausal women with asthma. Objective: To determine the impact of withdrawal of estrogen administration in postmenopausal, asthmatic women. Methods: Twenty asthmatic women who were postmenopausal for at least 2 years and undergoing ERT were recruited for this prospective crossover study. Subjects continued taking baseline estrogen for 28 days, stopped taking estrogen for 28 days, and then resumed taking the medication for 14 days. Objective measurements were obtained by recording daily peak flows in the morning and evening and formal spirometry at days 14, 28, 42, 56, and 70. Compliance was measured by evaluating serum estradiol levels at days 28 and 56. Daily use of short-acting β-agonist bronchodilators was also recorded. Results: Differences in estradiol levels indicated compliance with the medication regimen. The combined day 14 and 28 (taking estrogen) mean percent predicted forced expiratory volume in 1 second (FEV₁) was 77% compared with the combined day 42 and 56 (not taking estrogen) mean FEV₁ of 78% and the day 70 (taking estrogen again) FEV₁ of 76% (P>.05). Average peak flow measurements were 295.5 L/min for the duration of ERT, 293.9 L/min while not undergoing ERT, and 291.8 L/min when ERT was restarted for the final 2 weeks of the study (P>.05). Use of short-acting β-agonist bronchodilators did not differ between study periods. Conclusion: These data indicate that neither the discontinuation nor reinitiation of ERT in postmenopausal, asthmatic women has any effect on objective measures of airway obstruction.