Relationship between allergic rhinitis and diamine oxidase activity: A preliminary report.

Aim To analyze the diamine oxidase (DAO), the main catabolic enzyme of histamine, degradation activity and its relation with symptoms of persistent allergic rhinitis. Methods In this descriptive and analytical observational study, we collected DAO activity levels and the nasal peak inspiratory flow. Results Enzymatic activity deficit in 108 patients was 46.3% (95% CI, 0.44 - 0.63), 33.33% in mild and 47.92% in moderate/severe rhinitis (p = 0.376). The nasal peak inspiratory flow in patients with a deficit in DAO activity was 76.30 ± 28.40 L/min compared to 93.62 ± 37.50 L/min in patients with normal enzymatic activity (p = 0.010). Conclusions It seems that the lower the catabolic activity of DAO, the lower the nasal peak inspiratory flow observed. Although DAO activity levels could be a severity biomarker in allergic rhinitis, a cause-effect association cannot be concluded. The enzyme could be another actor in the pathophysiology of allergic rhinitis.