calca-protein--human and Anti-Neutrophil-Cytoplasmic-Antibody-Associated-Vasculitis

To review the current evidence regarding the value of measuring procalcitonin (PCT) levels in patients with systemic autoimmune diseases, with a focus on the evidence for diagnostic and analytical performance of this biomarker. A brief description of the pathophysiological basis of this biomarker is also included.. Using PubMed from the National Library of Medicine, relevant English literature on PCT in patients with different systemic autoimmune diseases, from 1990 to 2009, was reviewed. The search used keywords referring to procalcitonin and systemic lupus erythematosus, antineutrophil cytoplasmic antibody-associated systemic vasculitis, Goodpasture syndrome, rheumatoid arthritis, and giant cell arteritis.. When used in the appropriate clinical setting, the measurement of serum PCT levels is valuable as a marker of severe systemic bacterial and fungal infections and sepsis. Information regarding plasma PCT levels in patients with active underlying systemic autoimmune diseases is limited, primarily from observational studies and case series, with considerable variability of patient characteristics and clinical settings. In the detection of systemic infection concomitant with autoimmune diseases, PCT had a diagnostic sensitivity of 53 to 100% and a specificity of 84 to 97% (depending on the selection criteria) and was superior to other inflammatory markers tested. Most of the studies used a semiquantitative test for PCT measurement (functional assay sensitivity <0.5 ng/mL), which can explain the low sensitivity of the test. PCT levels were not significantly affected by renal function abnormalities or immunosuppressive agents. Although high PCT levels commonly occurred with infection, elevated levels of PCT could be found in patients with vasculitis without evidence of infection, often correlated with high disease activity scores.. Significantly elevated PCT levels offer good specificity and sensitivity for systemic infection in patients with systemic autoimmune diseases, regardless of the use of corticosteroids or immunosuppressive agents. PCT measurement may add to diagnostic accuracy in patients with systemic autoimmune diseases who present with a febrile illness, especially when highly sensitive PCT assays and specific PCT cutoff ranges are used in a predefined clinical setting (reflecting the likelihood of infection versus an autoimmune disease flare). However, there are limitations when using this biomarker in patients with systemic autoimmune diseases. PCT levels should not replace the necessary extensive diagnostic workup, which should include a thorough history and physical examination, combined with appropriate immunological, microbiological, radiological, and histological data.

Topics: Anti-Glomerular Basement Membrane Disease; Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis; Arthritis, Rheumatoid; Autoimmune Diseases; Biomarkers; Calcitonin; Calcitonin Gene-Related Peptide; Giant Cell Arteritis; Humans; Lupus Erythematosus, Systemic; Predictive Value of Tests; Protein Precursors

To determine whether platelet (PLT) counts might serve as a biomarker to distinguish between active anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) and remission and also between active disease and systemic infection.. PLTs were analysed before treatment in patients with AAV in the active state and in remission. PLTs were also analysed in AAV patients with acute infections. The results were correlated with clinical manifestations, the Birmingham Vasculitis Activity Score version 3 [BVAS(v.3)], and other laboratory findings [i.e. C-reactive protein (CRP), leucocytes, differential count, procalcitonin (PCT)]. Diagnostic accuracy was calculated with a receiver operating characteristic (ROC) curve.. PLT counts were significantly increased in 98 patients with AAV during the active disease state [median: 405 PLTs/nL; interquartile range (IQR) 288-504] compared to patients in remission (246 PLT/nL; IQR 214-289) (p < 0.001). We found a correlation of PLT counts in active disease with the BVAS(v.3) (r = 0.582, p < 0.001). In AAV patients with systemic infections (n = 37), PLT counts exhibited significantly lower values (226 PLT/nL; IQR 163-273) compared to patients with active disease (p < 0.001). In the ROC curve analysis, the area under the curve (AUC) of PLTs was significantly larger when distinguishing active disease from systemic infection (AUC 0.868) compared to leucocytes (AUC 0.590), CRP (AUC 0.522), or procalcitonin (AUC 0.515) (p < 0.001).. PLT counts were found to correlate with disease activity in AAV and thus may be used to represent immunological activity. In addition, PLT counts serve as a marker that can distinguish acute infection from active disease.

Topics: Adult; Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis; Biomarkers; Blood Platelets; C-Reactive Protein; Calcitonin; Calcitonin Gene-Related Peptide; Diagnosis, Differential; Female; Humans; Leukocyte Count; Male; Middle Aged; Platelet Count; Protein Precursors; Remission Induction; Severity of Illness Index