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C-reactive protein (CRP) by nephelometry

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

This test measures a protein in your blood that rises when your body is fighting inflammation or infection.

Quick summary

["High CRP levels may signal inflammation, often checked after injury, surgery, or illness."]

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

Key facts at a glance

LOINC
104686-1
Short code
DMA 18:0/C18:0 DBS
Synonyms
DMA 18:0/C18:0 DBS
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 This Test Is Done

Your doctor may order this test to monitor inflammation, assess risk for heart disease, or check for infections, autoimmune conditions, or post-procedure healing. High-sensitivity CRP helps detect mild inflammation that standard CRP tests might miss.

What to Expect Before the Test

No special preparation is needed. You’ll provide a blood sample drawn from a vein, typically in a lab setting. Results are usually available within 24–48 hours.

What the Results Mean

Results are reported in milligrams per liter (mg/L). Elevated levels may indicate inflammation, but they can also appear normal during acute illness or after minor trauma. Your doctor will interpret results in the context of your health history and symptoms.

Common Causes of Abnormal Results

High CRP levels can be caused by infections (bacterial or viral), autoimmune diseases (like rheumatoid arthritis), heart disease, or conditions requiring healing (e.g., surgery, injury). Low levels may suggest no active inflammation, but they can also occur with certain medications or chronic conditions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP (High-Sensitivity)

Frequently asked questions

How long does it take to get CRP test results?
Results are typically ready within 24 to 48 hours, depending on your lab’s processing time. Your doctor will contact you once they have the results.
Can diet or exercise affect CRP levels?
Yes, lifestyle factors like diet (e.g., Mediterranean diet), exercise, and weight management can influence CRP levels. Reducing inflammation through healthy habits may lower CRP over time.
Is CRP the same as a standard CRP test?
No, this is a high-sensitivity CRP test, which detects smaller amounts of CRP in the blood. Standard CRP tests are less sensitive and may not capture mild 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