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

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

This test measures the level of C-reactive protein, a protein produced by the liver in response to inflammation.

Quick summary

["CRP helps identify and monitor inflammation in your body."]

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

Key facts at a glance

LOINC
80361-9
Short code
C trach+GC rRNA Cvx Ql NAA+probe
Synonyms
C trach+GC rRNA Cvx Ql NAA+probe
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
probe-amp-tar
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?

Doctors may order a CRP test to check for signs of inflammation, monitor conditions like infections, autoimmune diseases, or heart disease, or evaluate responses to treatments. It can also help assess risk for conditions like heart attacks or certain cancers.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm or vein to draw blood. If you’re on blood thinners, let your healthcare provider know before the test.

What the Results Mean

Higher CRP levels often indicate inflammation, but they can also be influenced by factors like fever, infections, or certain medications. Your results will be discussed with your doctor to determine next steps.

Common Causes of Abnormal Results

Elevated CRP can be due to infections (like pneumonia or urinary tract infections), autoimmune diseases (like rheumatoid arthritis), heart or kidney problems, or other inflammatory conditions. Low levels may suggest no active inflammation or certain medical conditions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: CRP’s Role in Healthcare

Short name

CRP (Serum/Plasma)

Frequently asked questions

What factors might affect my CRP test results?
Several things can influence CRP levels, including recent infections, stress, smoking, certain medications (like steroids), or even physical activity. Your doctor will consider these factors when interpreting your results.
How often should I get this test?
The frequency depends on your health condition and treatment plan. Your doctor will decide how often to check CRP based on your specific needs, such as monitoring chronic diseases or evaluating responses to treatment.
Can I prepare for this test differently if I’m pregnant?
No special preparation is needed during pregnancy, but inform your healthcare provider about any medications you’re taking or if you suspect an infection. Your doctor may adjust the timing or frequency of the test if needed.
  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