What is C-Reactive Protein Blood Test and How this could Save Your Life

Medically reviewed by Dr. Aravind Pallipady

C-reactive protein (CRP) is a protein produced primarily by the liver and is designated a “Acute phase reactant”. This basically means that CRP is a clinical marker to hypothesize the severity of inflammation. The “C” in CRP was initially used to designate capsular antigen (C) polysaccharide of patients infected with Pneumococcus in the early 1930’s . Later CRP was researched extensively and was seen to be released as first responders to invading microorganisms like viruses and bacteria, which in turn helps in activating the immune responses to mount a robust defense.

What does an increased CRP level men to the patient?

CRP is elevated in numerous conditions including severe bacterial and fungal infections, autoimmune diseases like Rheumatoid Arthritis, osteomyelitis, Inflammatory bowel disease and Pelvic inflammatory disease among others. However the principal focus lies in the role of CRP in cardiovascular disease and stroke. Elevated serum CRP is a strong independent predictor of cardiovascular disease in asymptomatic individuals. CRP levels have been linked to prognosis in patients with atherosclerotic disease, congestive heart failure, myocarditis, atrial fibrillation, aortic valve disease and heart transplantation, suggesting that it has an active role in the pathophysiology of cardiovascular disease.

What should I be careful about while interpreting CRP reports?

CRP levels at any time may be influenced by underlying patient condition like simple flu like symptoms. Therefore, a single CRP measurement might be unpredictable. Hence two separate CRP levels are recommended two weeks apart to assess cardiovascular risk assessment and for screening purposes.

Are there any other substitutes to CRP testing?

Elevated Erythrocyte sedimentation rate (ESR) is another acute phase reactant However in comparison to CRP which rises and falls rapidly during inflammation, ESR has lesser advantages as it can be elevated in chronic inflammatory conditions too.
Elevated Total counts in blood and serum Ferritin are also used to gauge for severity of inflammation but these tests have their limitations.

What are the normal CRP values and when should I consult my doctor?

The normal range for CRP test depends on the lab and the test methodology that is employed. Generally, CRP levels under 10 mg/L is considered normal. A higher level will give a clue to your treating physician and he might ask additional tests to ascertain the exact cause of illness. It is important to note that CRP levels might be slightly elevated in conditions such as obesity, lack of exercise, cigarette smoking, diabetes and use of drugs like painkillers and steroids. Excessively and consistently high CRP levels is an indicator of acute infections, during which an immediate physician consultation is a must.