CRP (C-Reactive Protein) Test
A CRP test measures C-reactive protein, a substance the liver releases when there is inflammation somewhere in the body. It is a general marker, and clinicians use it to help evaluate whether an inflammatory process may be present, always in the context of symptoms and other findings.
About this test
C-reactive protein, or CRP, is made by the liver and rises in the bloodstream when the body responds to inflammation. Inflammation is a normal part of how the body reacts to many things — infection, injury, and a range of other processes — so CRP is considered a broad, nonspecific marker.
The CRP test is done with a simple blood draw at a patient service center. A phlebotomist collects a sample from a vein, usually in the arm, and the sample goes to the laboratory.
Who might consider this test?
- Because it is a general marker, it comes up in many different situations rather than pointing to any single one.
- Some people include it as part of a wider workup, while others test it because a clinician wanted a general read on inflammation.
Test details
| Quest code | 4420 |
|---|---|
| Methodology | Immunoturbidimetric |
| Sample type | 1 mL serum |
| Collection | Quest patient service center |
Reference range
<8.0 mg/L
Reference ranges are general guidance. The range printed on your own laboratory report is the one that applies to your result.
Related tests and panels
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Measures high-sensitivity C-reactive protein (hs-CRP), an inflammation marker…
Quest resources
Additional details
What this test looks at
CRP reflects the presence of inflammation in a general way. When the body mounts an inflammatory response, the liver releases more C-reactive protein, and the test picks up that change in the blood. Because so many processes can drive inflammation, CRP describes that something may be happening without identifying the cause.
It also helps to remember what CRP is not: it is not specific to any one organ or condition. That is exactly why a clinician reads it alongside symptoms and other tests rather than on its own, and why a single result is treated as one piece of a larger picture.
How it's often used alongside other tests
CRP is frequently ordered as part of a broader evaluation rather than in isolation. Depending on what a clinician is exploring, it may be paired with other blood work to add context. In cardiovascular risk conversations, a high-sensitivity CRP measurement is sometimes considered alongside lipid markers, since low-level inflammation is one factor clinicians weigh. Read together, these results offer more context than any single marker can on its own.
Order online and a physician order is included — no doctor's visit and no insurance needed. Your sample is collected at a Quest Diagnostics patient service center.
Laboratory results should always be interpreted by a licensed clinician who knows your health history. This page is information about a test, not medical advice.
Frequently asked questions
What does a CRP test measure?
It measures C-reactive protein, a substance the liver releases when there is inflammation in the body. It is a general marker that signals inflammation may be present without identifying its source.
What is the difference between CRP and high-sensitivity CRP?
They measure the same protein, but the high-sensitivity version can pick up lower-level inflammation. Clinicians sometimes use high-sensitivity CRP in cardiovascular risk conversations as one input among several.
How is the sample collected?
Through a routine blood draw at a patient service center. A phlebotomist takes a small sample from a vein in the arm and sends it to the laboratory.
Do I need to fast before a CRP test?
No preparation instructions are listed for this test, though people follow any instructions their ordering clinician provides.
Can a CRP test tell me what is causing inflammation?
No. CRP is a general marker that signals inflammation may be present but does not identify the cause. A clinician interprets it alongside symptoms, history, and other tests.
How much is a CRP test?
$29, paid once at checkout. The price includes the physician's order this test requires and sample collection at a Quest patient service center.