Primer: the practical use of biological markers of rheumatic and systemic inflammatory diseases.

The assessment of systemic inflammation by means of laboratory tests often complements the results of medical examination. Traditionally, the erythrocyte sedimentation rate and leukocytosis with left shift are diagnostic markers for inflammatory and infectious diseases. The levels of acute-phase proteins--especially C-reactive protein--are used to assess both the presence of inflammation and any response to treatment. The determination of C-reactive protein levels may be advised in three types of pathological situation: infection, acute or chronic inflammation, and evaluation of metabolic risk. Procalcitonin is useful as a marker of sepsis and severe infection. The concentration of serum amyloid A predicts the chances of survival of patients with secondary (AA) amyloidosis. Ferritin and its glycosylated form are of interest in the study of specific diseases such as adult-onset Still's disease. Markers of cartilage and bone turnover are complementary to these markers of inflammation. Although cytokine serum levels are transiently crucial to the generation of inflammation, their usefulness in the clinic is still under investigation. Serum concentrations of cytokine inhibitors or soluble cytokine receptors, as well as the clinical response of patients to treatment with cytokine antagonists, might generate important information for monitoring autoinflammatory diseases.