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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 your liver in response to inflammation in your body.

Quick summary

["CRP helps doctors assess inflammation, often used to monitor conditions like infections or autoimmune diseases."]

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

Key facts at a glance

LOINC
72922-8
Short code
HNA 1a-1a Ab Ser Ql IA
Synonyms
HNA 1a-1a Ab Ser Ql IA
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ia
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 Might Be Ordered

Your healthcare provider may order a CRP test to check for signs of inflammation, monitor chronic conditions like rheumatoid arthritis or lupus, or evaluate symptoms such as fever, joint pain, or unexplained swelling. It can also help determine if an infection is present or if you’re healing from one.

What to Expect Before the Test

No special preparation is needed for this blood test. You may be asked to fast for 8–12 hours before the draw if your lab requires it, but this is not always the case. Your blood will be drawn from a vein, usually in your arm, and it takes about 15 minutes total.

What the Results Mean

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

Common Conditions Monitored

CRP is often used to track conditions like inflammatory diseases (e.g., rheumatoid arthritis), infections (e.g., pneumonia), or post-surgery healing. It can also help guide decisions about treatments, such as steroids or antibiotics.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP (Neph)

Frequently asked questions

How often do I need this test?
The frequency depends on your health condition. For example, people with chronic inflammatory diseases may have CRP tested monthly or quarterly, while others may only need it once or twice a year. Your doctor will determine the schedule based on your needs.
Can diet or exercise affect CRP levels?
Yes, lifestyle factors can influence CRP levels. Eating a healthy diet rich in fruits, vegetables, and omega-3s, staying physically active, and managing stress may help lower CRP. Avoiding smoking and limiting alcohol can also support better inflammation control.
What if my CRP level is high?
A high CRP level may signal inflammation that needs further investigation. Your doctor could order additional tests, like blood cultures or imaging, to identify the cause. Treatment may include medications, lifestyle changes, or addressing underlying conditions like infections or autoimmune disorders.
  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