RESUMO
Abstract: Background: Serum amyloid A is an acute-phase protein. There is no available data regarding serum amyloid A levels in patients with acute and chronic urticaria (CU). Objective: To investigate the association between serum amyloid A and urticaria. Methods: This was a case-control study of 81 patients who visited our Hospital between June and December 2016 with a diagnosis of urticaria. Eighty healthy controls (HC) who visited for routine health examination and physical checkups were recruited. Serum amyloid A and C-reactive protein levels were measured by automated methods. Results: Serum amyloid A and C-reactive protein levels were significantly higher in AU (Serum amyloid A: 207.1 (6.7-439.0) mg/L; C-reactive protein: 16.0 (0.2-90.0) mg/L) and CU (Serum amyloid A: 6.5 (2.5-35.8) mg/L; C-reactive protein: 1.0 (0.1-16.0) mg/L) compared with HC (Serum amyloid A: 5.04 (2.0-9.1) mg/L; C-reactive protein: 1.2 (0.1-5.6) mg/L), and in AU compared with CU (all P<0.05). There were no differences between the CU and HC group. In CU, Serum amyloid A levels in those with moderate/severe urticaria (median, 16.4 (9.7-35.8) mg/L) were higher than in those with mild urticaria (median, 5.7 (2.5-9.5) mg/L) and HC (all P<0.05). Serum amyloid A and C-reactive protein levels exceeded the normal lab range in 90.7% and 72.1% patients with AU compared with 28.9% and 13.2% patients with CU, respectively. Significant positive correlations were found between serum amyloid A and C-reactive protein (r = 0.562, P < 0.001). Study limitations: There was no comparison between active disease and remission. Conclusion: There was an association between serum amyloid A levels and urticaria. Higher serum amyloid A levels were associated with AU and more severe CU. Serum amyloid A may help to identify CU patients earlier.