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C-reactive protein (CRP) – Serum/Plasma, Quantitative Immunoassay

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

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

Quick summary

["CRP helps identify and monitor inflammation, often used to check for infections, autoimmune conditions, or other inflammatory diseases."]

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

Key facts at a glance

LOINC
39909-7
Short code
NM Hrt FP+WM+VV+EF W Stress+W RNC IV
Synonyms
NM Hrt FP+WM+VV+EF W Stress+W RNC IV
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
nm
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 This Test Done?

Your healthcare provider may order a CRP test to check for signs of inflammation, monitor chronic conditions like rheumatoid arthritis or lupus, or evaluate symptoms such as fever, joint pain, or swelling. It can also help assess the effectiveness of treatments for inflammation-related illnesses.

What to Expect Before the Test

No special preparation is needed for this blood test. You may have a small needle inserted into your arm to draw blood, which usually causes only mild discomfort. If you’re on blood thinners, let your provider know before the test.

What the Results Mean

Higher-than-normal CRP levels often indicate inflammation, which can be caused by infections, injuries, or autoimmune diseases. Lower levels suggest minimal inflammation. Your provider will interpret results in the context of your overall health and symptoms.

Common Conditions Monitored

CRP is commonly used to monitor conditions like heart disease (e.g., atherosclerosis), infections (e.g., pneumonia, sepsis), and inflammatory diseases (e.g., inflammatory bowel disease, lupus). It can also guide decisions about starting or adjusting medications.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: CRP as an Inflammation Marker

Short name

CRP Level

Frequently asked questions

What causes elevated CRP levels?
Elevated CRP levels can be caused by infections (like bacterial infections), injuries, surgeries, or autoimmune diseases (like rheumatoid arthritis). Chronic conditions such as heart disease or certain cancers may also lead to higher CRP levels. Stress or certain medications can sometimes affect CRP levels too.
How often should CRP levels be checked?
The frequency of CRP testing depends on your medical condition and treatment plan. If you have a chronic inflammatory disease, your provider may recommend regular monitoring. For acute conditions like infections, testing may be done more frequently until symptoms improve.
Can diet or lifestyle affect CRP levels?
Yes, diet and lifestyle can influence CRP levels. Eating a heart-healthy diet, managing weight, exercising regularly, and reducing stress may help lower inflammation. Avoiding smoking and limiting alcohol can also support healthier CRP levels.
  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