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.