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C-reactive protein (CRP) by high-performance liquid chromatography (HPLC) or nephelometry

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

This test measures the level of C-reactive protein in your blood. CRP is a protein produced by your liver in response to inflammation.

Quick summary

["CRP helps identify inflammation in your body, which 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
72251-2
Short code
CT PA for PE
Synonyms
CT PA for PE
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?

Doctors may order CRP testing to check for signs of inflammation, monitor conditions like infections, autoimmune diseases, or heart disease, or evaluate responses to treatments. It can also help assess risk for certain health issues over time.

What Does a High or Low CRP Level Mean?

Elevated CRP levels often indicate inflammation, which may be due to infections, injuries, or conditions like arthritis or heart problems. Very low levels might suggest a lack of inflammation, but this can also occur with certain medications or health conditions. Your doctor will interpret results in the context of your overall health.

How Is This Test Performed?

A blood sample is taken from a vein, usually in your arm. The blood is then sent to a lab where it is analyzed using either HPLC or nephelometry to measure CRP levels.

What Should You Expect Before the Test?

No special preparation is usually needed, but you may be asked to fast for a few hours before the test if instructed by your healthcare provider. Wear comfortable clothing and bring any necessary medications with you.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP

Frequently asked questions

What are the typical reference ranges for CRP?
Reference ranges vary by lab and can depend on factors like age, health status, and medical conditions. Low levels (near zero) often indicate minimal inflammation, while higher levels signal possible inflammation or infection. Your doctor will use these results alongside other information to determine what they mean for you.
Can CRP levels change based on what I eat or drink?
Diet and lifestyle factors, such as eating anti-inflammatory foods or avoiding processed foods, may influence inflammation indirectly. However, CRP levels are primarily measured in response to actual inflammation in your body, so diet alone won’t change the test result directly.
How often should I get this test?
Your doctor will determine how often you need CRP testing based on your health condition, symptoms, and treatment plan. Some people may need it monthly, quarterly, or annually, while others may only need it occasionally or as needed for monitoring.
  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