Diagnosis of acute appendicitis (AA) remains a surgical dilemma, with negative appendectomy rates of 5% to 40% and perforation suggestive for late operative intervention in 5% to 30%. The aim of this study is to evaluate new plasma markers, representing early neutrophil activation, to improve diagnostic accuracy in patients suspected for AA.

Fifty-one patients who underwent surgery for AA were included (male-female = 28:23), and blood was sampled. Plasma concentrations of 2 neutrophil proteins were measured: lactoferrin (LF) and calprotectin (CP). Controls consisted of 27 healthy volunteers. C-reactive protein (CRP) and white blood cell count (WBC) concentrations were measured for routine patient care.

Median plasma concentrations for LF and CP were significantly higher in 51 patients with proven AA (665 and 766 ng/mL, respectively) than in 27 healthy volunteers (198 and 239 ng/mL, respectively, P < .001).

No clinically relevant correlation exists between the plasma levels of LF and CP and the conventional laboratory tests for CRP and WBC.

Circulating LF and CP levels are significantly elevated in patients with appendicitis and are detectable in plasma using relatively simple and low-cost enzyme-linked immunosorbent assays. Furthermore, plasma levels of LF and CP give additional information to conventional markers WBC and CRP, making them potential new markers for AA diagnosis.