Acute Phase Protein – Part 6 – C-Reactive Protein (CRP), High-Sensitivity C-Reactive Protein (hs-CRP)
Acute-phase protein (Acute Phase Reactants)
- Acute-phase protein is raised in inflammatory conditions.
- When there is an increase in a protein called positive acute-phase protein.
- In the case of a decrease in the acute phase protein, is called negative phase protein.
- The acute phase proteins (positive) are protein whose concentration increases in the plasma and after the disease episode is over then it decreases and may become normal.
C-Reactive Protein (CRP)
- The venous blood of the patient is needed to prepare the serum.
- A random sample can be taken.
- Analyze the fresh sample.
- Or can store at 4 °C for <72 hours.
- At -20 °C for 6 months.
- Advised in bacterial infection.
- It is advised in the rheumatic fever.
- It is advised in rheumatoid arthritis.
- May be advised after the surgery.
- This may be raised in cigarette smoking.
- Avoid hemolysed and lipemic samples.
- Raised values are seen in hypertension, diabetes mellitus, metabolic syndrome, gingivitis, and bronchitis.
- Decreased values have seen weight loss, moderate consumption of alcohol, and exercise.
- Estrogens and progesterone increase value.
- NIacin, statin, and fibrates decrease value.
- This is found in the Gamma-region band.
- CRP was given the name in 1941 that it is protein.
- This is a nonspecific acute-phase protein.
- CRP is functionally analogous to IgG, except it is not antigen-specific.
- hs-CRP detects the lower level of CRP which is important to find the risk of cardiac events.
- hs-CRP is useful for the risk of developing acute myocardial infarction with the history of acute coronary syndrome.
- This protein is synthesized in the liver and released into blood circulation after tissue injury in a few hours.
- This synthesis of the CRP is initiated by:
- Antigen immune complexes.
- Bacterial infection.
- Fungal infection.
- Trauma or tissue injury.
- This synthesis of the CRP is initiated by:
- This is the first acute phase protein raised in the inflammatory diseases and its level increases tremendously.
- This is raised in acute and chronic inflammation.
- This promotes the binding of Complement and helps in the phagocytosis.
- Its formation is initiated by the antigen-antibody immune complex.
- This can induce the production of cytokines.
- This can cause inhibition of chemotaxis and modulation of the WBC function.
- The normal CRP level is <2 to 3 mg/L.
- The markedly raised the level of >10 mg/L indicates an active inflammatory condition like collagen diseases and infection.
- Its level does not rise consistently in the virus infection.
- More sensitive and rapidly responding than the ESR.
- In the acute inflammatory process, CRP shows an earlier and more rapid increase than the ESR.
- In recovery, it becomes normal before the ESR.
- It disappears when the disease is treated with cortisone or salicylates.
- It may be advised after the surgery when its level increases in 4 to 6 hours.
- It starts going down after a 3rd postoperative day.
- If it persists raised level which indicates a complication of infection or pulmonary infarction.
- It helps in the differential diagnosis of bacterial or viral meningitis.
- In viral meningitis, it will be not raised.
- Normal value excludes bacterial meningitis.
- In myocardial infarction, CRP is raised and it correlates with CK-MB isoenzyme.
- Its peak level occurs 1 to 3 days later than CK-MB.
- If the level persists to be raised indicates ongoing damage to myocardial tissue.
- The baseline level is a good marker for future cardiovascular disease.
- CRP is a strong predictor of cardiovascular diseases than the low-density-lipoprotein (LDL), and cholesterol.
- In patients with stable coronary disease, CRP is a good marker in case of assessing the likelihood of recurrent myocardial infarction, or restenosis, or death.
- Its level is normal in the case of angina.
- <1.0 mg/dL
- Source 2
- <1.0 mg/dL or <10.0 mg/L
- Cardiac disease risk:
- Low = <1.0 mg/dL
- Average = 1.0 to 3.0 mg/dL
- High = >3.0 mg/dL
- Source 4
- CRP = <0.8 mg/dL (by nephelometry)
- CRP repotable value = 0.3 to 20 mg/dL
- hs-CRP = 0.020 to 0.800 mg/dL (by immunoassay)
Raised level is seen in:
- Soft tissue Trauma.
- Tissue necrosis.
- patients with Rheumatoid arthritis.
- In Rheumatic fever.
- Patients with systemic lupus erythematosus.
- Patient with pneumonia.
- patient with malignancies.
- In pregnant ladies.
- Pulmonary tuberculosis.
- Urinary tract infection.
- Myocardial infarction.
- Vasculitis syndrome.
- Bacterial meningitis.
Decreased CRP level is seen in:
- This may be seen in the moderate use of alcohol.
- In weight loss.
- Excessive exercise.
- Medicine like Niacin, and a statin.