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C-reactive protein (CRP) by nephelometry (serum/plasma)

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

This test measures a protein produced by your liver in response to inflammation or infection. It helps doctors track conditions like arthritis, heart disease, or infections.

Quick summary

["A simple blood test to monitor inflammation levels in your body."]

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

Key facts at a glance

LOINC
24571-2
Short code
NM BDs+GB Bil Pat+EF W Sinc+RNC IV
Synonyms
NM BDs+GB Bil Pat+EF W Sinc+RNC IV
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
nm
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

What Is CRP Used For?

CRP is often used to check for signs of inflammation, which can occur with infections (such as pneumonia or urinary tract infections), autoimmune diseases (like rheumatoid arthritis), or after surgery or trauma. High levels may also signal heart disease risk.

How Is CRP Tested?

Your blood is drawn, and the CRP protein is measured using a special lab technique called nephelometry. This test is usually done on a sample of your serum or plasma.

Why Might You Need This Test?

Your doctor may order this test if you have symptoms of inflammation, a history of chronic conditions, or if you’re at risk for heart disease. It can also help monitor treatment progress for certain conditions.

What Are Common Results?

Results are not given as a single range since they vary by lab and condition. Instead, doctors compare your CRP level to your medical history and symptoms to interpret results.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: CRP is a marker for inflammation. While it doesn’t diagnose a specific condition, it helps guide treatment decisions, especially in conditions like rheumatoid arthritis or cardiovascular risk assessment. Very high levels may require further investigation.

Short name

CRP (High Sensitivity)

Frequently asked questions

Why do I need this test if I don’t have symptoms?
Even without symptoms, your doctor may check CRP to monitor long-term health risks, like heart disease, or to assess inflammation in conditions you already have.
What if my CRP is higher than usual?
A higher CRP level may signal inflammation, but it doesn’t always mean an infection or disease. Your doctor will discuss next steps, such as additional tests or treatments, based on your overall health.
Can I affect my CRP levels?
Yes, lifestyle factors like diet, exercise, and smoking can influence CRP. Reducing inflammation may help lower CRP levels over time, but this depends on the underlying cause.
  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