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Acute phase protein (Acute Phase Reactants)

C-Reactive Protein (CRP)



  1. Advised in bacterial infection.
  2. It is advised in the rheumatic fever.
  3. It is advised in rheumatoid arthritis.
  4. May be advised after the surgery.



  1. This is found in the Gamma-region band.

  1. CRP  was given the name in 1941 that it is protein.
    1. This is nonspecific acute phase protein.
  2. This protein is synthesized in the liver and released into blood circulation after tissue injury in few hours.
  3. This is the first acute phase protein raised in the inflammatory diseases and its level increases tremendously.
  4. This is raised in acute and chronic inflammation.
  5. This promotes the binding of Complement and helps in the phagocytosis.


  1. Its formation is initiated by the antigen-antibody immune complex.

  1. This can induce the production of cytokines.
  2. This can cause inhibition of chemotaxis and modulation of WBC function.
  3. Normal CRP level is <2 to 3 mg/L.
    1. The markedly raised level of >10 mg/L indicates an active inflammatory condition like collagen diseases and infection.
  4. More sensitive and rapidly responding than the ESR.
    1. In recovery, it becomes normal before the ESR.
    2. It disappears when the disease is treated with the cortisone or salicylates.
  5. It may be advised after the surgery when its level increases in 4 to 6 hours.
    1. It starts going down after a 3rd postoperative day.
    2. If it persists raised level which indicates a complication of infection or pulmonary infarction.
  6. It helps in the differential diagnosis of bacterial or viral meningitis.
    1. In viral meningitis, it will be not raised.
    2. Normal value exclude bacterial meningitis.


Raised level is seen in:

    1. Soft tissue Trauma.
    2. Infection.
    3. Tissue necrosis.
    1. patients with Rheumatoid arthritis.
    2. In Rheumatic fever.
    3. Patients with systemic lupus erythematosus.
    4. Patient with pneumonia.
    5. patient with malignancies.
    6. In pregnant ladies.
    7. In myocardial infarction, CRP is raised and it correlates with CK-MB isoenzyme.
      1. Its peak level occurs after 1 to 3 days (this is late than the enzyme CK-MB).
      2. If the level persists to be raised indicates ongoing damage to myocardial tissue.
      3. Its level is normal in the case of angina.
    8. Pulmonary tuberculosis.
    9. Urinary tract infection.
    10. Vasculitis syndrome.
    11. Bacterial meningitis.

Decreased CRP level is seen in:

  1. This may be seen in the moderate use of alcohol.
  2. In weight loss.
  3. Excessive exercise.
  4. Medicine like Niacin, and a statin.

Possible References Used

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