C-Reactive Protein (CRP)

Alternate Test Name: C-Reactive Protein 

Description: The CRP test is used to identify and/or monitor inflammation in patients.

Also Known As: CRP Test, Inflammation test

Collection Method: Blood Draw

Specimen Type: Serum

Test Preparation: No preparation required

When is a C-Reactive Protein test ordered?

When a person's medical history and signs and symptoms indicate that they may have a significant bacterial infection, a CRP test may be recommended. When a newborn displays signs of infection or when a person has sepsis symptoms including fever, chills, and rapid breathing and heart rate, it may be ordered.

It's also commonly requested on a regular basis to check illnesses like rheumatoid arthritis and lupus, and it's routinely repeated to see if medication is working. This is especially effective for inflammation issues because CRP levels decrease as inflammation decreases.

What does a C-Reactive Protein blood test check for?

C-reactive protein is a protein produced by the liver and released into the bloodstream within a few hours following tissue injury, infection, or other inflammatory event. After trauma or a heart attack, with active or uncontrolled autoimmune illnesses, and with acute bacterial infections like sepsis, markedly higher levels are reported. CRP levels can rise by a thousand-fold in response to inflammatory diseases, and their elevation in the blood can occur before pain, fever, or other clinical signs. The test detects inflammation caused by acute situations or monitors disease activity in chronic diseases by measuring the level of CRP in the blood.

The CRP test is not a diagnostic tool, although it can tell a doctor if inflammation is occurring. This information can be combined with other indicators like signs and symptoms, a physical exam, and other tests to establish whether someone has an acute inflammatory disorder or is having a flare-up of a chronic inflammatory disease. The health care provider may next do additional tests and treatment.

This CRP test should not be confused with the hs-CRP test. These are two separate CRP tests, each of which measures a different range of CRP levels in the blood for different purposes.

Lab tests often ordered with a C-Reactive Protein test:

Conditions where a C-Reactive Protein test is recommended:

Commonly Asked Questions:

How does my health care provider use a C-Reactive Protein test?

A health practitioner uses the C-reactive protein test to diagnose inflammation. CRP is an acute phase reactant, a protein produced by the liver and released into the bloodstream within a few hours following tissue injury, infection, or other inflammatory event. The CRP test is not a diagnostic test for any ailment, but it can be used in conjunction with other tests to determine whether a person has an acute or chronic inflammatory disorder.

CRP, for example, can be used to detect or track substantial inflammation in someone who is suspected of having an acute ailment like:

People with chronic inflammatory diseases can use the CRP test to detect flare-ups and/or see if their medication is working. Here are a few examples:

CRP is occasionally requested in conjunction with an erythrocyte sedimentation rate, another inflammatory test. While the CRP test is not specific enough to diagnose an illness, it does serve as a broad marker for infection and inflammation, alerting doctors to the need for more testing and treatment. A variety of additional tests may be used to determine the source of inflammation, depending on the probable cause.

What do my C-Reactive Protein test results mean?

CRP levels in the blood are usually low.

CRP levels in the blood that are high or rising indicate the existence of inflammation, but they don't tell you where it is or what's causing it. A high CRP level can establish the presence of a severe bacterial infection in people who are suspected of having one. High levels of CRP in persons with chronic inflammatory disorders indicate a flare-up or that treatment isn't working.

When the CRP level rises and then falls, it indicates that the inflammation or infection is diminishing and/or responding to treatment.

Is there anything else I should know about C-Reactive Protein?

CRP levels can rise during pregnancy, as well as with the use of birth control tablets or hormone replacement therapy. Obese people have also been found to have higher CRP levels.

In the presence of inflammation, the erythrocyte sedimentation rate test will also rise; however, CRP rises first and then falls faster than the ESR.

We advise having your results reviewed by a licensed medical healthcare professional for proper interpretation of your results.