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C-reactive protein (CRP) in plasma by nephelometry

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

This test measures the level of C-reactive protein in your blood, which helps assess inflammation in your body.

Quick summary

["CRP is a marker for inflammation that can signal infections, injuries, or other health conditions."]

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

Key facts at a glance

LOINC
36902-5
Short code
C trach+GC DNA Spec Ql NAA+probe
Synonyms
C trach+GC DNA Spec 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 rheumatoid arthritis, infections (e.g., sepsis), or evaluate responses to treatments. It can also help identify risks for heart disease or other chronic conditions.

What Does a High CRP Level Mean?

Elevated CRP levels often indicate inflammation. While high levels can point to infections, autoimmune diseases, or injuries, they don’t always pinpoint the exact cause. Your doctor will use the results alongside other tests and symptoms to guide diagnosis.

What Does a Low CRP Level Mean?

Low CRP levels usually mean there’s little to no inflammation in your body. However, very low levels might raise concerns if you have conditions like rheumatoid arthritis or other inflammatory diseases, so follow-up testing may be needed.

How Is This Test Performed?

A blood sample is drawn from a vein in your arm. The blood is then sent to a lab, where it’s analyzed using a nephelometry method to measure CRP levels accurately.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP (Plasma)

Frequently asked questions

What conditions might affect CRP levels?
CRP levels can be influenced by infections (e.g., pneumonia, urinary tract infections), autoimmune diseases (e.g., lupus, rheumatoid arthritis), heart disease, trauma, or certain medications. Chronic conditions like obesity or smoking may also affect CRP levels over time.
How soon will I get my results?
Results are typically available within 24 to 48 hours, depending on your lab’s processing time. Your doctor will discuss the results with you during your follow-up appointment.
Can I eat or drink before this test?
You can eat and drink normally before this test, as it doesn’t require fasting. However, always follow your doctor’s specific instructions for your appointment.
  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