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C-reactive protein (CRP) – Serum/Plasma Substance 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 your body.

Quick summary

["CRP helps doctors identify and monitor inflammation, often used to check 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
81256-0
Short code
COSMIC simple var ID
Synonyms
COSMIC simple var ID
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 evaluate symptoms like fever, joint pain, or unexplained fatigue. It can also help monitor conditions such as heart disease, rheumatoid arthritis, or infections like pneumonia or sepsis. CRP levels may rise quickly in response to inflammation, making it useful for early detection.

What to Expect Before the Test

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

What the Results Mean

CRP results are often interpreted alongside other tests and your medical history. Higher-than-normal levels may suggest inflammation, while lower levels might indicate reduced inflammation. Your provider will discuss the results in the context of your health.

Common Conditions Monitored

CRP is commonly used to assess conditions like infections (e.g., bacterial infections), autoimmune diseases (e.g., lupus, rheumatoid arthritis), or cardiovascular risks. It can also help track how well treatments are working for chronic inflammatory diseases.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP

Frequently asked questions

What factors could affect my CRP levels?
Several factors can influence CRP levels, including recent infections, injuries, or illnesses. Smoking, stress, obesity, and certain medications (like steroids) may also affect results. It’s important to discuss any recent health events or medications with your provider before interpreting the test.
Can CRP levels be affected by diet or exercise?
Yes, lifestyle factors like diet, exercise, and weight can impact inflammation. For example, a healthy diet rich in fruits, vegetables, and omega-3s may help lower CRP levels, while sedentary behavior or poor diet might raise them. Your provider may recommend lifestyle changes if needed.
How often should CRP be checked?
The frequency of CRP testing depends on your health condition. Some people may need CRP checked yearly or more often if they have chronic inflammation or a history of infections. Your provider will determine the best schedule for you based on your needs.
  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