Serum amyloid A:: A novel serum marker for the detection of systemic inflammatory response in cystitis

Purpose: We compared serum amyloid A (SAA) protein, C-reactive protein (CRP), interleukin IL-6 and tumor necrosis factor (TNF)-alpha as inflammatory markers for pyelonephritis and cystitis. Materials and Methods: SAA, CRP, IL-6 and TNF-alpha were determined in serum from 69 consecutive patients with acute pyelonephritis (37) and acute cystitis (32) on admission to an infectious disease clinic and on examination at a primary health care center, respectively. Healthy blood donors served as controls. Results: SAA showed a systemic inflammatory response in cystitis in 90% of patients compared with 23%, 42% and 0% for CRP, IL-6 and TNF-alpha, respectively. SAA and CRP had equally high efficiencies (0.96 and 0.94, respectively) for discriminating between pyelonephritis and cystitis while efficiencies for IL-6 (0.85) and TNF-alpha (0.91) were lower. Conclusions: SAA is a sensitive systemic marker in cystitis but is still useful in detecting pyelonephritis.