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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 doctors assess 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
35973-7
Short code
CT LE-Bl
Synonyms
CT LE-Bl
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

What Is C-Reactive Protein?

C-reactive protein (CRP) is a marker your body produces when tissues are damaged or inflamed. It’s often checked to see if there’s an active inflammatory process, such as an infection, injury, or certain diseases like rheumatoid arthritis or heart disease.

Why Might You Need This Test?

Your doctor may order CRP testing to monitor chronic conditions, check for signs of infection, evaluate response to treatment, or assess risk for conditions like heart disease or stroke. It can also help guide decisions about medications or further testing.

How Is the Test Done?

A small amount of blood is drawn from a vein in your arm. The blood sample is sent to a lab where it’s analyzed using nephelometry, a method that measures how much CRP is present in your serum or plasma.

What Do the Results Mean?

Results are typically reported in milligrams per liter (mg/L). Higher levels may indicate inflammation, infection, or other health issues, while lower levels suggest minimal inflammation. Your doctor will interpret results in the context of your overall health and symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP (Nephelometry)

Frequently asked questions

How often will I need this test?
The frequency depends on your health condition and treatment plan. Some people get CRP tests regularly to monitor chronic inflammation, while others may need it only if symptoms or other tests suggest inflammation is present.
Can I eat or drink before this test?
For most CRP tests, you can eat and drink normally as there are no special preparations. However, if your doctor has specific instructions, follow them to ensure accurate results.
What are the possible side effects of the blood draw?
Blood draws are generally safe, but you might feel slight discomfort or bruising at the site. Rarely, there could be minor swelling or pain. If you experience excessive bleeding or signs of infection (like redness or fever), contact your doctor.
  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