The seven most commonly measured inflammatory markers are CRP, ESR, IL‑6, TNF‑α, fibrinogen, complement proteins, and white blood cell count.
CRP and ESR: quick systemic screens
C‑reactive protein is produced by the liver in response to IL‑6. High sensitivity tests can detect low‑grade inflammation that predicts cardiovascular events. The erythrocyte sedimentation rate measures how fast red cells settle; a faster rate indicates increased plasma proteins and inflammation.
IL‑6 and TNF‑α: key cytokines
IL‑6 is released by macrophages and T cells during infection or injury and stimulates CRP and fibrinogen production. Elevated IL‑6 is seen in rheumatoid arthritis, metabolic syndrome, and cytokine storms.
TNF‑α is produced mainly by activated macrophages and drives systemic inflammation. It is the target of anti‑TNF biologics used in Crohn’s disease, psoriasis, and rheumatoid arthritis.
Fibrinogen: clotting and inflammation
Fibrinogen is an acute‑phase reactant that increases blood viscosity. High levels raise the risk of atherosclerosis, heart attack, and stroke.
Complement proteins: immune surveillance
Complement components C3 and C4 participate in antibody‑mediated clearance. Low C4 or high C3 can signal lupus activity or other immune complex diseases.
White blood cell count and differential
Leukocytosis indicates acute infection or trauma. A chronic, mild elevation may reflect ongoing low‑grade inflammation from obesity or stress. The differential (neutrophils, lymphocytes, eosinophils, basophils, monocytes) helps identify the infection type or allergic response.
Putting the markers together
Clinicians rarely rely on a single marker. A pattern—elevated CRP and IL‑6 with a high ESR, for example—strengthens the evidence for systemic inflammation and guides further testing or treatment.