Abstract: Objective: To detect the serum activity of diamine oxidase in chronic urticaria and analyze its correlation with urticaria severity, so as to explore its significance in the pathogenesis of chronic urticaria. Methods: Serum diamine oxidase activity were determined by spectrophotometry in 68 patients with chronic urticaria and 54 healthy control. The activity and the urticaria severity were compared by using linear correlation. Results: The serum diamine oxidase activity in 1 hour, 1.5 hour and 3 hours was lower than that of healthy control. There were significant difference between 1.5/ 3 hours and control group (P<0.01). The correlation between the activity and the urticaria severity is significant (P<0.05). Conclusion: The serum diamine oxidase activity in chronic urticaria patients decreased, which might be implicated with the chornic pathogenesis and urticaria severity.

Key words: chronic urticaria , diamine oxidase, histamine