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Quantitative Immunoassay for C-Reactive Protein (CRP) in Plasma

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

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

Quick summary

["CRP helps doctors assess inflammation, track conditions like infections or autoimmune diseases, and monitor treatment progress."]

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

Key facts at a glance

LOINC
101172-5
Short code
CT + NG + TV rRNA Pnl Spec NAA+probe
Synonyms
CT + NG + TV rRNA Pnl Spec 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 CRP Testing Matters

CRP is a marker that rises when your body is fighting inflammation. High levels may signal infections, injuries, or conditions like arthritis or heart disease. Your doctor may order this test to check for these issues or to monitor ongoing treatments.

What to Expect Before the Test

No special preparation is needed. You’ll have a small needle inserted into your arm to draw a blood sample. It usually takes a few minutes. If you’re on blood thinners, let your doctor know before the test.

What the Results Mean

Results are not given in absolute numbers but as a comparison to a general reference range. Low or normal levels suggest little to no inflammation. Elevated levels may indicate active inflammation or infection. Your doctor will interpret results in the context of your health and symptoms.

Common Conditions Monitored

Doctors use CRP to diagnose or monitor conditions such as infections (e.g., pneumonia, urinary tract infections), autoimmune diseases (e.g., rheumatoid arthritis, lupus), heart disease, or inflammatory bowel disease. It can also help guide decisions about starting or stopping certain medications.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: CRP’s Role in Healthcare

Short name

CRP Level (Plasma)

Frequently asked questions

Will my CRP test show if I have a hidden infection?
CRP can signal inflammation but isn’t always definitive for infections. A positive CRP result may prompt further testing (like blood cultures or imaging) to identify the cause. Some infections (e.g., viral) may not raise CRP levels.
Can CRP levels change with diet or exercise?
Diet and exercise can influence inflammation indirectly. For example, a healthy diet may reduce chronic inflammation, but CRP results alone don’t reflect lifestyle changes. Your doctor will consider overall health factors when interpreting results.
Is CRP testing the same as a complete blood count (CBC)?
No, CRP is a specific protein marker for inflammation, while a CBC checks for red/white blood cells and platelets. Both tests serve different purposes—CRP focuses on inflammation, while a CBC assesses blood cell health.
  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