Premenstrual asthma - Epidemiology, pathogenesis and treatment

The exacerbation of asthma in the premenstrual period has long been of inte rest. Premenstrual asthma has been estimated to affect up to 40% of females with asthma, although the exact prevalence of this phenomenon is unclear a s studies have involved small numbers in hospital clinics. Large-scale comm unity-based studies are required to estimate its true prevalence. Researchers are slowly piecing together clues as to the aetiology and patho genesis of the disorder. Female sex-steroid hormones play an important role but the exact mechanism is still unknown. Recent evidence suggests that in creased airway hyperresponsiveness, an indicator of underlying airway infla mmation, during the luteal phase of the menstrual cycle may account for pre menstrual exacerbations. In addition, there is now evidence of impaired or altered beta (2)-adrenoceptor function and regulation in females with asthm a, which may have a part to play. Accurate diagnosis is dependent on a detailed history and the demonstration of premenstrual dip in peak expiratory flow. Exacerbations in the majority of women will respond to the usual treatment of bronchial asthma. However, a few women will experience significant morbidity or treatment-related adv erse effects. Case reports suggest that the combined oral contraceptive pil l or gonadotrophin-releasing hormone analogues may be effective in these pa tients. This requires substantiation by randomised controlled trials.