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

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

This test measures the amount of C-reactive protein in your blood. CRP is a protein produced by your liver in response to inflammation, helping your immune system identify and clear infections or injuries.

Quick summary

["CRP helps track inflammation, guiding treatment for infections, autoimmune conditions, or other health concerns."]

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

Key facts at a glance

LOINC
109562-9
Short code
C trach Ag Msmt Bld
Synonyms
C trach Ag Msmt Bld
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why This Test Is Done

Doctors may order CRP testing to monitor for or diagnose conditions like infections (e.g., pneumonia, urinary tract infections), autoimmune diseases (e.g., rheumatoid arthritis, lupus), heart disease, or inflammation after surgery or injury. It can also help assess how well certain treatments are working.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm to draw blood, which usually takes a few minutes. If you’re on blood thinners, let your provider know before the test.

What the Results Mean

Results are not typically provided as a single number but are often compared to a reference range for your age/health status. High CRP levels may signal inflammation, while very low levels might indicate a lack of infection or disease activity.

Common Conditions Affecting Results

Factors like infections, injuries, certain medications (e.g., steroids), or chronic conditions (e.g., heart disease) can raise CRP levels. Smoking, obesity, or stress may also influence results.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP Level

Frequently asked questions

How often should I get this test?
Your doctor will determine the frequency based on your symptoms, medical history, and treatment plan. Some people get it yearly for routine check-ups, while others may need it more often if they have ongoing health concerns.
Can diet or lifestyle changes affect CRP levels?
Yes! Reducing inflammation through diet (e.g., Mediterranean diet), exercise, quitting smoking, and managing stress can lower CRP levels. Ask your doctor about personalized recommendations.
What if my CRP is unusually high or low?
High CRP may prompt further testing (e.g., blood cultures, imaging) to investigate infections or other causes. Low CRP could mean your body isn’t responding to inflammation, but it doesn’t rule out all conditions—your doctor will discuss next steps with you.
  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