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C-reactive protein (CRP) 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 in your body.

Quick summary

["CRP helps identify inflammation, often used to monitor conditions like infections, autoimmune diseases, or after surgery."]

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

Key facts at a glance

LOINC
24544-9
Short code
CT TA
Synonyms
CT TA
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ct
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 a CRP test to check for signs of inflammation. It can help diagnose conditions like infections (such as pneumonia or appendicitis), monitor chronic diseases (such as rheumatoid arthritis or lupus), or assess how well you’re healing after surgery or an injury.

What to Expect Before the Test

No special preparation is usually needed. You may be asked to fast for 8–12 hours before the test if your blood is drawn from a vein, but this depends on your lab’s instructions. If you’re having a urine sample collected, follow any hydration guidelines provided.

How the Test Works

Blood is drawn from a vein in your arm, and the sample is analyzed using a nephelometry method to measure CRP levels. CRP is a protein that rises when your body is fighting inflammation.

What the Results Mean

Results are typically reported in milligrams per liter (mg/L). Higher levels may indicate inflammation, infections, or other health issues. Your doctor will interpret the results in the context of your overall health and medical history.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

CRP (Nephelometry)

Frequently asked questions

What Does a High CRP Level Indicate?
A high CRP level often signals inflammation in your body, which can be caused by infections (like bacterial infections), autoimmune diseases (such as rheumatoid arthritis), or other conditions like heart disease or cancer. It’s not specific to one disease but helps guide further testing or treatment decisions.
What Does a Low CRP Level Indicate?
A low CRP level usually means there is little to no inflammation detected in your blood. However, it doesn’t rule out all possible causes of inflammation, so your doctor may still recommend additional tests if needed.
How Often Should I Get This Test?
The frequency of CRP testing depends on your health condition and treatment plan. Your doctor may recommend it periodically to monitor inflammation levels, especially if you have a chronic illness or are undergoing treatment for an inflammatory condition.
  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