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C-reactive protein (CRP) – Serum

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

This blood 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 assess inflammation, which may signal infections, injuries, or other health conditions."]

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

Key facts at a glance

LOINC
37873-7
Short code
Deprecated Skull XR 1V Ltd
Synonyms
Deprecated Skull XR 1V Ltd
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
xr
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 This Test Is Done

Doctors may order a CRP test to monitor conditions like arthritis, heart disease, or infections. It can also help check for signs of inflammation after surgery, trauma, or other medical procedures.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into a vein in your arm to draw blood. If you’re nervous, let your healthcare provider know so they can help make it more comfortable.

What the Results Mean

Higher CRP levels often indicate inflammation, but they don’t always point to a specific cause. Your doctor will compare your results with your medical history and other tests to understand what’s happening in your body.

Common Conditions Monitored

CRP is used to track conditions such as rheumatoid arthritis, heart disease (like atherosclerosis), and infections like pneumonia or sepsis. It can also help evaluate responses to treatments.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

CRP plays a key role in identifying and managing inflammatory diseases. While it doesn’t diagnose a condition directly, it helps doctors determine whether inflammation is present and guides treatment decisions, such as adjusting medications or planning further tests.

Short name

CRP

Frequently asked questions

What does a high CRP level mean?
A high CRP level suggests inflammation is active in your body, which could be due to infections, autoimmune diseases, or other health issues. Your doctor will review your results alongside other factors to determine the next steps.
Can I eat or drink before this test?
You can eat and drink normally before the test unless your doctor specifies otherwise. No fasting is required for CRP testing.
How long does it take to get my results?
Results are typically available within a few days to a week, depending on your lab’s processing time. Your doctor will contact you with the final results when they’re ready.
  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