CRP / C-Reactive Protein Test

C-Reactive Protein (CRP) is produced by the liver and can increase when inflammation is present. CRP is nonspecific, which means an elevated result does not identify the cause by itself. Healthcare professionals interpret it together with symptoms and other investigations.

C-reactive protein is made by the liver and can rise when inflammation is present. A standard CRP test is often used when a clinician wants to assess or monitor a broad inflammatory response. It does not identify the cause or location of inflammation by itself.

Standard CRP and high-sensitivity CRP (hs-CRP) are not interchangeable. hs-CRP uses a more sensitive method and may be used in selected cardiovascular-risk assessment settings, while a standard CRP is commonly used for inflammatory or infectious conditions. The report should therefore be checked for the exact assay ordered.

Routine CRP is commonly used when a clinician wants a broad measure of current inflammatory activity. It may be repeated to see whether an inflammatory process is improving or worsening, but the trend is meaningful only when interpreted with the illness being monitored. A very low CRP does not make every infection or inflammatory disorder impossible, and an elevated CRP can occur after surgery, injury or other tissue damage. If cardiovascular risk assessment is the purpose, confirm that the requested test is high-sensitivity CRP rather than standard CRP.

CRP may be requested when a clinician is assessing inflammation, infection or response to treatment. The reason for testing and the trend over time are often more useful than a single isolated value.

CRP is a protein that can rise relatively quickly when there is inflammation in the body. A raised result can be seen with infection, tissue injury and many inflammatory conditions, but standard CRP does not identify the source or cause. The size of the increase and the way it changes over time can be useful when a clinician is monitoring an illness or response to treatment.

Standard CRP and high-sensitivity CRP (hs-CRP) are not interchangeable. hs-CRP is designed for much lower concentrations and can be used in selected cardiovascular-risk assessments; a routine CRP result should be interpreted for the purpose for which it was ordered.

CRP is nonspecific. It cannot on its own distinguish bacterial from viral infection, prove an autoimmune diagnosis or determine the location of inflammation. Some inflammatory conditions may produce little CRP response, and a value can change rapidly as an illness evolves. Interpretation therefore depends on symptoms, examination, timing and any related tests.

CRP is measured from a blood sample. Fasting is usually not required for standard CRP alone. Tell the clinician or laboratory about medicines and supplements because some can influence inflammatory markers or the context in which results are interpreted.