Acute Phase Reactants: Relevance in Dermatology

Acute phase reactants (APRs) are a heterogeneous group of plasma proteins whose concentration either increases or decreases by at least 25% during an inflammatory process. The conditions that commonly lead to acute phase response are infection, trauma, burns, tissue infarction, inflammatory conditions, and advanced malignancy. APRs are elevated in all infective conditions. In skin and soft tissue infection, the levels of erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) help to predict the severity of infection. Procalcitonin can be used to differentiate between viral and bacterial infections. During active stages of systemic lupus erythematosus (SLE), ESR is elevated, but CRP either remains normal or shows only moderate elevation. In the case of superadded bacterial infection in SLE, CRP is elevated. In SLE, ferritin levels are elevated during the active stage of the disease. Serum amyloid antigen (SAA) and CRP levels are significantly higher in patients with early and late stages of diffuse systemic sclerosis. Elevated levels of serum ferritin are seen in rheumatoid arthritis and adult-onset Still's disease. CRP, SAA, and α2-macroglobulin (α ₂M) are elevated in active psoriasis. In severe psoriasis, the ferritin-iron ratio is elevated. In drug-induced maculopapular rash, drug-induced hyperaemic vasculitis, and severe drug-induced cutaneous adverse reactions, CRP levels are elevated during the active stages. Neoplastic diseases in general are accompanied by increased serum ferritin. Further detailed studies are required to explore the clinical significance of APRs in dermatology and the scope of their possible application as a diagnostic tool.