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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 produced by the liver in response to inflammation in the body.

Quick summary

["CRP helps identify inflammation, often used to monitor conditions like infections or autoimmune diseases."]

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

Key facts at a glance

LOINC
45006-4
Short code
C trach IgA Ser IA-aCnc
Synonyms
C trach IgA Ser IA-aCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ia
CPT
82784
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 doctor may order a CRP test to check for signs of inflammation, monitor chronic conditions like arthritis or heart disease, or evaluate responses to treatments. It can also help diagnose infections or assess risks for conditions like heart disease or certain cancers.

What to Expect Before the Test

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

What the Results Mean

Higher CRP levels may indicate inflammation, while lower levels suggest reduced inflammation. Your results will be compared to a general reference range provided by your lab.

Common Conditions Monitored

CRP is often used to monitor conditions like rheumatoid arthritis, lupus, or heart disease. It can also help track infections or responses to treatments for inflammatory diseases.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: CRP is a marker for systemic inflammation. Elevated levels may signal infections, autoimmune disorders, or other inflammatory processes. It’s not diagnostic on its own but often used alongside other tests for a full picture.

Short name

CRP (Serum/Plasma)

Frequently asked questions

What causes CRP levels to change?
CRP levels can rise due to infections (like colds or flu), injuries, surgeries, or certain medications. They may also be affected by chronic conditions like arthritis or heart disease. Stress or recent illness can temporarily increase CRP.
How long does it take to get results?
Results are typically available within 1–3 business days, depending on your lab. Your doctor will discuss them with you during your follow-up visit.
Can diet or exercise affect CRP levels?
Yes, lifestyle factors like diet (e.g., Mediterranean diet), exercise, and weight management can influence CRP levels. Reducing inflammation through healthy habits may lower CRP over time.
  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