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C-reactive protein (CRP) concentration in serum/plasma

Published: August 9, 2026Updated: August 16, 2026

This test measures the level of C-reactive protein, a protein produced by the liver in response to inflammation in your body.

Quick summary

["CRP helps doctors assess inflammation, often used to monitor conditions like infections, autoimmune diseases, or heart disease."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
12264-8
Short code
Deprecated EBV EA-R Ab Fld-mCnc
Synonyms
Deprecated EBV EA-R Ab Fld-mCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why Is CRP Tested?

Your healthcare provider may order this test to check for signs of inflammation, monitor chronic conditions, or evaluate symptoms like fever, joint pain, or swelling. It can also help determine if you have an infection or if your immune system is overreacting.

When Might You Need This Test?

You might need this test if you have symptoms like persistent fever, unexplained weight loss, joint pain, or if you’re being evaluated for conditions like rheumatoid arthritis, lupus, or heart disease. It’s also used before surgeries or procedures to check for hidden inflammation.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours if your blood is drawn early in the morning. Wear a loose shirt for easy access to your arm.

What Happens During the Test?

A healthcare professional will insert a small needle into your arm to draw a small amount of blood. The process takes only a few minutes, and you may feel a brief pinch. The blood is then sent to a lab for analysis.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP

Frequently asked questions

CRP is a marker for inflammation. High levels can indicate infections, autoimmune diseases, or other inflammatory conditions. While it doesn’t pinpoint the exact cause, it helps guide treatment decisions and monitor progress over time.
CRP levels alone don’t diagnose a condition but can support other tests or symptoms. For example, high CRP might suggest an infection, but your doctor will consider other factors like symptoms and lab results.
What Does a High CRP Level Mean?
A high CRP level often means your body is fighting inflammation or infection. Your doctor may recommend further testing or treatment based on the cause, such as antibiotics for infections or medications for autoimmune diseases.
What If My CRP Level Is Low?
A low CRP level usually means there’s less inflammation in your body. However, it doesn’t rule out all causes of symptoms—other tests may still be needed to find the root issue.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy