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C-reactive protein (CRP) – Serum Substance Concentration

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 track inflammation, often used to check for infections, autoimmune conditions, or other health concerns."]

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

Key facts at a glance

LOINC
49378-3
Short code
HCV RNA Mar NAA+probe-aCnc
Synonyms
HCV RNA Mar NAA+probe-aCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
probe-amp-tar
CPT
86803
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?

Your healthcare provider may order a CRP test to monitor inflammation, evaluate symptoms like fever, joint pain, or swelling, or check for conditions like infections, heart disease, or certain autoimmune disorders. It can also help guide treatment decisions.

What Does a High or Low CRP Level Mean?

A high CRP level often signals inflammation, which can be caused by infections, injuries, or inflammatory diseases. A low level usually means less inflammation is present, though it doesn’t rule out other conditions. Your results will be interpreted by your doctor based on your overall health.

Sample Collection and Preparation

A blood sample is drawn from a vein, usually in your arm. The blood is sent to a lab where it is processed into serum (the liquid part after blood clots). This test does not require fasting, but your doctor may provide specific instructions.

Common Conditions Monitored

CRP is commonly used to assess conditions like rheumatoid arthritis, lupus, heart disease, infections (such as pneumonia or sepsis), and other inflammatory diseases. It can also help track how well treatment is working.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

CRP (Serum)

Frequently asked questions

What factors might affect my CRP levels?
Several factors can influence CRP levels, including recent infections, injuries, smoking, stress, certain medications (like steroids), and underlying health conditions. Your doctor will consider these factors when reviewing your results.
How soon will I get my results?
Results are typically available within 24 to 48 hours, depending on your lab’s processing time. Your healthcare provider will discuss the findings with you during your follow-up visit.
Can I do anything to prepare for this test?
No special preparation is needed for this test. Avoid heavy meals before the blood draw if instructed by your doctor, but otherwise, you can eat and drink as usual.
  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