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

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

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

Quick summary

["CRP helps doctors check for inflammation in your body."]

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

Key facts at a glance

LOINC
14513-6
Short code
C trach Ag UrnS Ql IF
Synonyms
C trach Ag UrnS Ql IF
Category
chemistry
Sample
urine
Container
Sterile urine container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
if
Specimen volume
10 mL
Stability
Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

What Is C-Reactive Protein?

C-reactive protein (CRP) is a marker your body produces when tissues are damaged or when there’s an infection or inflammation. It’s often checked to monitor conditions like heart disease, autoimmune disorders, or infections. CRP doesn’t directly indicate the cause of inflammation but helps track how active it is over time.

Why Might You Need This Test?

Your doctor may order CRP testing if you have symptoms of inflammation, such as fever, joint pain, or swelling, or if you’re at risk for conditions like heart disease, arthritis, or infections. It can also be used to monitor treatment progress for certain conditions.

How Is the Test Done?

A blood sample is taken from a vein in your arm. The sample is sent to a lab where CRP levels are measured using a sensitive immunoassay technique. Results are typically available within a few days.

What Do the Results Mean?

Higher CRP levels may suggest inflammation, infection, or other health issues. Your doctor will interpret the results in relation to your symptoms and medical history. Some reference ranges vary by lab, so ask your provider for guidance.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP

Frequently asked questions

What causes CRP levels to change?
CRP levels can rise due to infections (like pneumonia or urinary tract infections), injuries, surgeries, or certain medications. They may also fluctuate with chronic conditions like arthritis or heart disease. Stress, smoking, or poor diet can temporarily affect results too.
How long does it take to get results?
Results are usually ready within 2–5 business days, depending on your lab’s processing time. Your doctor will contact you once they’re available.
Can CRP levels be affected by diet or supplements?
Yes, certain foods (like omega-3 fatty acids) or supplements (like fish oil) may lower CRP levels. Avoiding alcohol and smoking can also help keep levels more stable. Always discuss dietary changes with your doctor before making adjustments.
  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