Diagnostic Value of Procalcitonin in ANCA-Associated Vasculitis (AAV) to Differentiate Between Disease Activity, Infection and Drug Hypersensitivity

Abstract

Objective: Procalcitonin (PCT) is considered to be a specific marker for severe bacterial infections and sepsis. Elevated PCT levels have been reported in active autoimmune diseases without infection.The aim of this study was to assess the diagnostic value of PCT serum levels in ANCA-associated vasculitis (AAV) patients with respect to infection, disease activity and drug fever using a high sensitive PCT detection method.Methods: In 53 AAV patients with elevated C-reactive protein (CRP) PCT was determined by the Thermo Scientific BRAHMS PCT sensitive KRYPTOR assay. Patients underwent standardized diagnostic procedures for evaluation of disease activity and infection.Results: 53 patients with AAV and elevated CRP (7.7±6.9 mg/dl, PCT 0.34±1.02 ng/ml) were assessed, 10 had infection with elevated CRP levels of 11.2±10.2 mg/dl and PCT levels of 1.06±2.07 ng/dl. 43 patients had no evidence of infection, 36 of them were presented with AAV with normal or only slightly positive PCT levels in active disease (n=36) (PCT 0.06±0.06 ng/ml). 7 patients had increased PCT levels due to azathioprine hypersensitivity (0.76±1.01 ng/ml). For discrimination between infection and vasculitis activity PCT was more useful than CRP with the best cut-off at 0.1 ng/ml (sensitivity 60%, specificity 92%).Conclusion: In contrast to previous studies using semiquantitative PCT assays, the KRYPTOR performs better with respect to discrimination of infection from active AAV. In all patients assessed with active AAV (and without infection) PCT levels remained below the PCT reference limit (0.5 ng/ml) for infections. Drug hypersensitivity seems to be an important differential diagnosis in the setting of elevated CRP and PCT in patients who receive azathioprine.

False Positive COVID-19 Antibody Test in a Case of Granulomatosis With Polyangiitis

“…The concept of COVID-19 induced vasculitis in the context of viral-induced ANCA-associated vasculitis could not be verified as three nasopharyngeal swab tests were negative for SARS-CoV-2 ( 2 ). Slight elevations of procalcitonin levels may also be attributed to the systemic vasculitis as has been previously reported ( 5 ).…”

The Plasma Soluble Urokinase Plasminogen Activator Receptor Is Related to Disease Activity of Patients with ANCA-Associated Vasculitis

“…To date, a few studies investigated AAV patients for PCT levels. Studies showed that AAV patients without evidence of infection could have elevated serum PCT levels, but other reports possess opposite results that PCT was not significantly increased in disease activity in various autoimmune diseases including GPA [45][46][47], so further investigations are needed to discuss this controversial issue. Briefly, plasma suPAR could serve as a factor reflecting an inflammatory condition, but further studies are still needed to clarify whether increased suPAR is caused by overactivation of inflammation in patients with AAV or if it actually exerts a proinflammatory role.…”

Biomarkers in ANCA-Associated Vasculitis: Potential Pitfalls and Future Prospects

“…A large cross-sectional study of the Birmingham Vasculitis Activity Score 3 (BVAS) provided confirmation of this demonstrating a poor correlation between BVAS and CRP with a limited role for such inflammatory markers in assessing disease activity (58) . Other inflammatory markers such as calprotectin, hepcidin and procalcitonin have also been evaluated, but face the same limitation (57,(59)(60)(61)(62)(63)(64) .…”