Recommendations for the measurement of the most important plasma proteins

This document, prepared on behalf of the SIBioC Protein Working Group, reviews the existing evidence for recommending the measurement of the most important plasma proteins. For each protein, the related chapter includes: a) a brief introduction describing main biological characteristics, b) the presentation of the available evidence, based on retrieved meta-analyses, systematic reviews, and international and national guidelines, and c) recommendations for the test ordering. The scientific evidence was searched on electronic databases (Medline, Cochrane's database of systematic reviews) and on the websites of scientific societies. Recommendations were classified on the basis of the source of the retrieved evidence as follows: (+++) official National or International guidelines, (++) meta-analyses or systematic reviews, (±) expert opinions and/or clinical practice, and (-) none (not recommended). The following proteins were considered in the paper: albumin, α 1-antitripsin, α 1-acid glycoprotein, α 2-macroglobulin, haptoglobin, β 2- microglobulin, C-reactive protein (both as marker of inflammation and cardiovascular risk), ceruloplasmin, cystatin C, complement factors, rheumatoid factor, ferritin, immunoglobulins (IgA, IgG, IgM, IgD), free light chains, retinol binding protein, soluble transferrin receptor, serum amyloid A, transferrin, and transtyretin.