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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 the body.

Quick summary

["CRP helps 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
107504-3
Short code
CUZD1 IgA Ser Ql IF
Synonyms
CUZD1 IgA Ser Ql IF
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
if
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 healthcare provider may order a CRP test to monitor inflammation, assess infection risk, evaluate conditions like rheumatoid arthritis, heart disease, or kidney problems, or check for signs of an infection before symptoms appear. It can also help guide treatment decisions for certain conditions.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm to draw blood, which usually takes a few minutes. Avoid strenuous activity or heavy meals 24 hours before the test if instructed by your provider.

What to Expect During the Test

The blood sample is collected in a tube and sent to a lab for analysis. Results are typically ready within a few days, depending on lab processing times.

Possible Results and Interpretation

CRP levels vary by individual. Higher than normal levels may indicate inflammation, infection, or other health issues. Your provider will discuss 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)

Frequently asked questions

What Does a High CRP Level Mean?
A high CRP level often signals inflammation in the body, which can be caused by infections (like pneumonia or urinary tract infections), autoimmune diseases (like lupus or rheumatoid arthritis), or other conditions such as heart disease. It’s not specific to one disease but helps guide further testing or treatment plans.
What Does a Low CRP Level Mean?
Low CRP levels usually mean there is little to no inflammation detected in your body. However, very low levels might also indicate a lack of detectable inflammation, which could be normal or may require further evaluation if you have symptoms of inflammation or illness.
Can CRP Levels Change Over Time?
Yes, CRP levels can fluctuate based on your health status, recent infections, medications, or other factors. Regular monitoring may be needed if you have a chronic condition or ongoing treatment for inflammation.
  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