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C-reactive protein (CRP) – Serum/Plasma Concentration

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

["CRP helps track inflammation, often used to monitor conditions like infections, autoimmune diseases, or heart risks."]

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

Key facts at a glance

LOINC
37229-2
Short code
XR tomo TMJ-L
Synonyms
XR tomo TMJ-L
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
xr-tomography
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 It’s Done

Your doctor may order this test to check for signs of inflammation, monitor chronic conditions (like rheumatoid arthritis or heart disease), or evaluate responses to treatments. High levels may suggest infections, injuries, or other inflammatory processes.

What to Expect

A small blood sample is taken from your arm. The sample is sent to a lab where it’s analyzed to measure CRP levels. Results are typically ready within a few days.

What the Results Mean

Results are reported in milligrams per liter (mg/L). While reference ranges vary by lab, higher-than-normal levels may indicate inflammation or infection. Your doctor will interpret results in the context of your health.

Common Conditions Monitored

This test is often used to monitor conditions like cardiovascular disease, infections (e.g., pneumonia), autoimmune disorders (e.g., lupus), or to assess healing after surgery or injury.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP (High-Sensitivity)

Frequently asked questions

What causes CRP levels to be high?
High CRP levels can be caused by infections (like flu or urinary tract infections), injuries, surgeries, autoimmune diseases (like rheumatoid arthritis), or other inflammatory conditions. Stress, certain medications, or even recent exercise can also temporarily affect CRP levels.
How often should I get this test?
Your doctor will determine how often you need this test based on your health needs. Some people get it once a year for routine checks, while others may need it more often if they have ongoing conditions like heart disease or autoimmune disorders.
Can lifestyle changes affect CRP levels?
Yes! Lifestyle factors like diet, exercise, and smoking can influence CRP levels. Eating a heart-healthy diet, staying active, and avoiding smoking may help lower inflammation over time. Always discuss lifestyle changes with your doctor before making significant adjustments.
  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