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C-reactive protein, serum/plasma concentration (high-sensitivity)

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

This test measures a protein called C-reactive protein (CRP) in your blood. CRP is a marker that helps your body detect inflammation, often in response to infection, injury, or other conditions causing inflammation.

Quick summary

["CRP helps doctors assess inflammation levels and guide treatment plans."]

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

Key facts at a glance

LOINC
100121-3
Short code
C trach IgA Ser Ql IA
Synonyms
C trach IgA 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
CPT
82784
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 CRP Measures

CRP is produced by your liver in response to inflammation. While CRP itself isn’t harmful, it signals the body’s immune system is active. High CRP levels may indicate conditions like infections, autoimmune diseases, or other inflammatory processes.

Why It’s Done

Your healthcare provider may order this test to monitor chronic conditions (e.g., heart disease, rheumatoid arthritis), check for infections, or evaluate symptoms like fever, joint pain, or unexplained fatigue. High-sensitivity CRP is particularly useful for detecting mild to moderate inflammation.

How It’s Done

A small blood sample is drawn from a vein, usually in your arm. The blood is processed to separate serum or plasma, where CRP levels are measured using a sensitive immunoassay technique.

What to Expect Before or After

No special preparation is needed, but inform your provider if you’re on blood-thinning medications. After drawing blood, you may feel slight discomfort, but it typically resolves quickly. Avoid heavy exercise or caffeine 30 minutes before the test if instructed.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

hs-CRP

Frequently asked questions

How often should I get this test?
Your provider will determine the frequency based on your health needs. For example, people with heart disease may get it every few months, while others with stable conditions might check it less often. Follow their guidance—don’t alter timing without advice.
What do my results mean?
Results are usually reported in micrograms per milliliter (µg/mL). A normal range isn’t absolute—it depends on your health status. High levels may trigger further testing or adjustments to treatment, while low levels suggest inflammation is under control. Ask your provider to explain what your specific result means for you.
Can lifestyle changes affect CRP levels?
Yes! Diet, exercise, and stress management can influence inflammation. Regular physical activity, a balanced diet (rich in fruits, vegetables, and omega-3s), and reducing smoking/alcohol may lower CRP levels. Small, sustainable changes often have the biggest impact over time.
  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