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C Reactive Protein (CRP)!! Is it really important? 

1. What is C Reactive Protein /CRP?

Following inflammation, certain serum protein levels are either increased or decreased by at least 25 %. Such proteins are called -Acute phase reactants (APR). CRP was the first acute phase reactants discovered in a patient affected with acute phase of pneumococcal pneumonia which was discovered way back in 1930.

CRP helps in non-specific host defense against microbial organism by activating certain molecules in the immune system. CRP is not only just a marker of inflammation, but it also plays an active role in the inflammatory process.

2. What is the importance of CRP?

CRP level is elevated in acute & chronic inflammatory conditions, non-communicable diseases, infectious & non-infectious diseases. A CRP test helps in monitoring the high level of CRP in the body. 


3. What is a normal CRP level?

Unit of C-reactive protein concentration is reported in both mg/dl and md/L. CRP is normally present in plasma at a concentration below 0.5 mg/dl (5mg/L). CRP level more than 1 mg/dl (10mg/L) is considered clinically significant. CRP level of 0.3 to 1 mg/dl(3-10 mg/L) can be considered as low-grade inflammation or metabolic stress. Moderate to marked elevation of CRP is a value above 10 mg/dL (100 mg/L) and are strongly associated with infection.


4. What are the causes of elevated CRP?

CRP are elevated in some conditions where CRP blood test can be used to monitor the disease activity or to assess the prognosis. Others are as follows:

  1. Infection-Highest concentration of CRP was usually found in serum following usually following bacterial infection. But can be seen in a higher concentration following uncomplicated influenza & infectious mononucleosis
  2. To Monitor disease activity in Rheumatoid arthritis
  3. Malignancy 
  4. Polymyalgia rheumatica (PMR) and giant cell arteritis (GCA)
  5. Cardiovascular disease -Will increase markedly following myocardial infarction; Mild increase in CRP level is associated with risk of cardiovascular disease
  6. Others like - stress, trauma, following surgery, etc.

CRP along with other acute phase reactants are used to monitor many inflammatory & infectious diseases.

5. What is high sensitivity CRP? 

High-sensitivity CRP means CRP concentration is determined using an assay that can estimate and distinguish very low levels of CRP. The methods used for high sensitivity CRP are particle enhanced (latex enhanced) light scattering assays or sandwich type immunoassays.

Certain studies have reported that a high concentration of high sensitivity CRP is a stronger predictor of myocardial infarction, stroke, peripheral vascular disease & future coronary events which can be learned through a CRP blood test.

Dr. Sruthi P

Senior Specialist
MD Pathology