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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 substance 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 after certain treatments."]

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

Key facts at a glance

LOINC
111916-3
Short code
Procedure outcome Endscpy
Synonyms
Procedure outcome Endscpy
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
endoscopy
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 CRP is Tested

Doctors may order this test to check for signs of inflammation, monitor chronic conditions like rheumatoid arthritis or lupus, or evaluate responses to treatments. It can also help diagnose infections, such as pneumonia or appendicitis, or identify risks for heart disease.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if it involves drawing blood from a vein. Wear comfortable clothing and plan to stay near the testing site for a short time.

What Happens During the Test

A healthcare professional will insert a small needle into a vein in your arm to draw a blood sample. You may feel a brief pinch, but it’s usually over quickly. The blood is then sent to a lab for analysis.

What the Results Mean

Results are reported in milligrams per deciliter (mg/dL). Higher levels may indicate inflammation, infection, or other health issues. Your doctor will interpret the results in the context of your medical history and symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP (Serum/Plasma)

Frequently asked questions

What causes CRP levels to be high?
High CRP levels can result from infections (like bacterial or viral), injuries, surgeries, or certain medical conditions such as rheumatoid arthritis, lupus, or heart disease. Stress, smoking, or certain medications may also influence CRP levels.
How long does it take to get results?
Results are typically available within 1–3 business days, depending on your lab’s processing time. Your doctor will contact you once they have the results.
Can I lower my CRP levels naturally?
Yes! Reducing inflammation may involve lifestyle changes such as eating a balanced diet, exercising regularly, managing stress, and avoiding smoking. If you have a chronic condition, follow your doctor’s recommendations for managing symptoms.
  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