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C-reactive protein (CRP) by nephelometry

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

This test measures a protein produced by your liver in response to inflammation, helping detect or monitor low-to-moderate levels of inflammation in your body.

Quick summary

["Helps track subtle inflammation, often used for early detection of conditions like infections or autoimmune diseases."]

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

Key facts at a glance

LOINC
4496-6
Short code
Deprecated C3d-C3d+Gg-iC3b Recep WBC Ql
Synonyms
Deprecated C3d-C3d+Gg-iC3b Recep WBC Ql
Category
coagulation
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
4.5
Ref high
11
Critical range
2 N/A – 30 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
85004
SNOMED
900000000000003002
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?

Your doctor may order this test to check for signs of inflammation, especially if you have symptoms like fever, fatigue, or joint pain. It’s also used to monitor conditions like heart disease, arthritis, or infections where inflammation plays a role.

What to Expect Before the Test

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

What the Results Mean

Higher-than-normal levels may indicate inflammation, infections, or certain diseases. Lower-than-normal levels might suggest reduced immune response, but this isn’t always the case. Your doctor will interpret results in the context of your overall health.

Common Conditions Monitored

This test is often used to monitor conditions like cardiovascular disease, rheumatoid arthritis, or to check for early signs of infection or inflammation in people with weakened immune systems.

Reference range

Adult: 4.5-11.0 x 10^9/LN/A

Specimen: serum

No special preparation required. Stay well hydrated.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: CRP is a marker of systemic inflammation. While it doesn’t pinpoint the exact cause, elevated levels can signal potential health risks and guide treatment decisions, such as adjusting medications or starting preventive care.

Short name

CRP (High Sensitivity)

Frequently asked questions

What does a high CRP level mean?
A high CRP level often suggests inflammation is present in your body, which could be due to infections, autoimmune conditions, or other health issues. Your doctor will review your symptoms and other test results to determine the cause.
Can diet or exercise affect CRP levels?
Yes, lifestyle factors like diet, exercise, and stress can influence CRP levels. Eating a balanced diet, staying active, and managing stress may help lower inflammation over time.
Is CRP the same as a general infection test?
No, CRP measures inflammation broadly, while tests like white blood cell count or specific antibodies detect infections more directly. CRP helps track inflammation’s role in conditions like arthritis or heart disease.
  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