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

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

This test measures a protein in your blood that rises when your body is fighting inflammation or infection.

Quick summary

["High CRP levels may signal inflammation, infections, or other health concerns—results help guide follow-up care."]

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

Key facts at a glance

LOINC
15282-7
Short code
Deprecated Cultivated Rye IgE Qn
Synonyms
Deprecated Cultivated Rye IgE Qn
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 This Test Matters

High-sensitivity CRP (hs-CRP) is a blood test often used to monitor low-grade inflammation, which can occur with conditions like heart disease, autoimmune disorders, or chronic infections. It’s not typically ordered for routine checkups but may be used after an injury, surgery, or if you have symptoms like fever, fatigue, or joint pain.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm for a blood draw, which usually takes just a few minutes. If you’re on blood thinners, let your provider know before the test.

Common Conditions Monitored

Doctors may order this test to check for inflammation in conditions like rheumatoid arthritis, heart disease, or after a heart attack. It can also help assess response to treatment for infections or autoimmune diseases.

What the Results Mean

Results are reported in milligrams per liter (mg/L) or micrograms per milliliter (µg/mL). While reference ranges vary by lab, very high levels may indicate severe inflammation or infection, while very low levels might suggest no active inflammation. Your provider will interpret results in the context of your health history.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

CRP (High-Sensitivity)

Frequently asked questions

What causes elevated CRP levels?
Elevated CRP can be caused by infections (like pneumonia or urinary tract infections), injuries, surgeries, or inflammatory diseases (like lupus or heart disease). Stress, smoking, or certain medications can also affect CRP levels.
Can CRP levels be affected by diet or exercise?
Yes, lifestyle factors like diet, exercise, and smoking can influence CRP levels. For example, a healthy diet and regular physical activity may help lower CRP, while smoking or poor diet can raise it.
How often should I get this test?
Your provider will determine how often you need this test based on your health needs. It’s often done periodically if you have a condition that requires monitoring inflammation, such as heart disease or autoimmune disorders.
  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