Table 1.

Acute Phase Reactants

ESR	Extremely elevated ESR (>100 mm/hour)-high specificity for infection, malignancy, or arteritis. Rises within 24–48 hours of the onset of inflammation and falls back slowly with resolution.
CRP	Begins to rise after 12–24 hours and peaks within 2–3 days. Low levels of CRP elevation with values between 2 and 10 mg/L measured by a “high sensitivity CRP” assay seen in noninfectious “metabolic inflammatory” states such as cardiac ischemia, uremia, or smoking.
PCT	Detectable within 3–4 hours and peaks within 6–24 hours. Elevated levels not seen in other noninfectious inflammatory conditions such as polymyalgia, inflammatory bowel disease, polyarteritis nodosa, systemic lupus erythematosus, gout, and temporal arteritis. More sensitive and specific than CRP for distinguishing bacterial from noninfectious causes of inflammation
Others	Apolipoproteins: SAA proteins Coagulation Pathway: Fibrinogen, Protein S, Plasminogen Complement System: C3, C4, C9, Factor B, C1 inhibitor Antiproteases: Alpha-1 antitrypsin, Alpha-1 acid glycoprotein Proteins: Haptoglobin, Hemopexin, Hepcidin, Ferritin, Ceruloplasmin Cytokines: IL-1, IL-6, tumor necrosis factor-alpha

Abbreviations: CRP, C-reactive protein; ESR, erythrocyte sedimentation rate; IL, interleukin; PCT, procalcitonin; SAA, serum amyloid A.