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CRP is an abbreviation for C-reactive protein, which is a substance manufactured by the body during the inflammatory process. CRP results can help to diagnose conditions where inflammation occurs, or to monitor response to the treatment of such conditions. CRP results are obtained from a CRP test, which is a routine blood test done on a blood sample taken from a vein. Depending on the laboratory doing the test, normal CRP levels range between 0 and 1 mg/dL (less than 10 mg/L).
When inflammation occurs, either acutely such as after trauma or in an acute disease, or chronically, such as in arthritis or inflammatory bowel disease, the liver synthesizes CRP. CRP results that are high indicate that inflammation is present, either acutely or chronically. Doctors use CRP results for both diagnosis and monitoring of treatment. As the body responds to treatment, inflammation should subside, and the CRP levels should decrease.
CRP results may be high in a number of acute situations. Injury, such as trauma causing inflammation, may increase them while the area is inflamed. CRP levels are also often raised after a myocardial infarction, or heart attack. An increase in CRP after surgery may indicate post-operative infection, which requires further investigation. CRP may also increase late in pregnancy. In the case of liver failure, it may decrease.
In the case of more chronic conditions, such as arthritis and inflammatory bowel disease, CRP results are used as part of a series of diagnostic tests. Treatment of these conditions is often aimed at reducing the inflammation associated with them, as this is often the cause of their symptoms. Monitoring CRP to check that it is decreasing is one indication that the treatment is working.
Occasionally healthy people are tested for CRP to assess their risk for cardiac disease. A high-specificity CRP test is done in this situation, as the rise in CRP may be very small. This increase may warn patients of an higher risk of heart disease and, therefore, promote prevention tactics such as lifestyle changes.
While CRP results can be useful, they are not used exclusively for diagnosis or monitoring of treatment. The CRP test is just one test that may be done in combination with others, such as white cell counts in the case of acute infection, and used by doctors to ensure optimal medical care and treatment. Follow-up tests may be recommended according to the CRP results obtained.