Biochemical markers as a response guide for steroid therapy in asthma

Background. Exhaled breath condensate pH and hydrogen peroxide concentration is a non-invasive, simple and inexpensive assay that can be performed for monitoring in patients with asthma. Objective. To evaluate the possibility of usefulness of expired breath condensate pH and H2O2 concentration as well as serum total antioxidant capacity and malondialdehyde as markers for steroid treatment response. Patients and methods. A total of 153 patients were included in this study (age range 18 to 64 years). Asthmatic patients, regularly followed for at least 3 months, were randomly recruited for the study over a period of one month. All patients received inhaled beclomethasone dipropionate (1,000 mu g daily in four divided doses) and salbutamol inhalers (800 mu g daily in four divided doses) for 4 weeks. Expired breath condensate was collected at the end of the study to determine hydrogen peroxide concentration and pH. Venous blood samples were collected for determination of total antioxidant capacity and malondialdehyde as markers of peroxidation. Results. In asthmatic patients with poorly controlled asthma, expired breath condensate hydrogen peroxide concentration was higher and the pH was lower than stable asthma. Serum malondialdehyde concentration in poorly controlled asthma was higher (6.98 mu mol/L), and total antioxidant capacity was lower (589 mu mol/L) than in stable asthma. Conclusion. Exhaled hydrogen peroxide concentration and pH can be used as predictors for monitoring of nonresponse to asthma treatment.