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C-reactive protein (serum/plasma concentration)

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 doctors assess inflammation, often used to monitor conditions like infections, autoimmune diseases, or after surgery."]

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

Key facts at a glance

LOINC
22161-4
Short code
CVV Ab Ser Ql
Synonyms
CVV Ab Ser Ql
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 evaluate your response to treatment. It can also help identify infections or other inflammatory processes in your body.

What to Expect Before the Test

No special preparation is usually needed. You may be asked to fast for 8–12 hours before the test if it’s drawn from a blood sample, but this depends on your provider’s instructions. Avoid strenuous activity the day before if advised.

How the Test Works

Blood is drawn from a vein, typically in your arm. The sample is sent to a lab where it’s analyzed to measure CRP levels using an immunoassay method, which detects the protein’s presence and concentration.

What the Results Mean

Higher CRP levels often indicate inflammation, while lower levels suggest reduced inflammation. Your results will be compared to your provider’s clinical judgment and other test results to guide diagnosis or treatment.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: CRP is a non-specific marker of inflammation. Elevated levels may signal infections (e.g., bacterial), autoimmune diseases (e.g., lupus), or other inflammatory conditions. It’s not diagnostic alone but supports broader evaluation.

Short name

CRP (Serum/Plasma)

Frequently asked questions

What causes CRP to be elevated?
CRP can rise due to infections (like pneumonia or urinary tract infections), injuries, surgeries, or certain medical conditions such as rheumatoid arthritis or heart disease. Stress, smoking, or obesity may also influence 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 provider will discuss the meaning with you during follow-up.
Can lifestyle changes lower CRP levels?
Yes! Reducing inflammation may involve improving diet (e.g., anti-inflammatory foods), exercising regularly, managing stress, quitting smoking, and treating underlying conditions like high cholesterol or diabetes.
  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