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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 the liver in response to inflammation, often used to check for signs of infection, injury, or other inflammatory conditions.

Quick summary

["Helps detect low-grade inflammation that may not show up on other tests."]

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

Key facts at a glance

LOINC
107505-0
Short code
CUZD1 IgG Ser Ql IF
Synonyms
CUZD1 IgG 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 It’s Done

Your doctor may order a high-sensitivity CRP test if you have symptoms like fever, fatigue, or unexplained swelling, or if you’re at higher risk for conditions like heart disease or autoimmune disorders. It can also be used to monitor treatment progress for certain conditions.

What to Expect

A small needle will draw blood from a vein in your arm. You may feel a slight pinch, but it usually doesn’t cause discomfort afterward. The test is quick and requires no special preparation.

How Results Are Used

Higher-than-normal levels may signal inflammation, while lower levels could mean your body is responding to treatment or your condition is stable. Your doctor will interpret results in the context of your overall health.

Common Causes of Abnormal Results

Elevated CRP can occur with infections (like pneumonia or urinary tract infections), injuries, surgeries, or conditions like rheumatoid arthritis or heart disease. Chronic low-grade elevation may also appear with certain cancers or metabolic disorders.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical significance: Elevated CRP is a general marker of inflammation and can help guide treatment decisions, but it’s not diagnostic on its own. It’s often used alongside other tests to assess risk or monitor disease activity.

Short name

CRP (High-Sensitivity)

Frequently asked questions

What does a high CRP mean?
A high CRP level suggests inflammation is present in your body, which could be due to infection, an injury, or an autoimmune condition. Your doctor will review the result with your full medical history and other test results to determine the next steps.
Does CRP change with diet or exercise?
While diet and exercise can influence inflammation in general, CRP levels are primarily a response to acute or chronic health events. Small lifestyle changes may support overall health, but they don’t directly alter CRP test results.
How often should I get this test?
Your doctor will determine the frequency based on your health needs. Some people get it once a year as a routine check, while others may need it more often if they have a chronic condition or risk factors 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