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C-reactive protein (CRP) – Serum/Plasma 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 monitor conditions like infections, autoimmune diseases, or after surgery."]

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

Key facts at a glance

LOINC
21596-2
Short code
VZV IgM Titr CSF IF
Synonyms
VZV IgM Titr CSF IF
Category
chemistry
Sample
csf
Container
Sterile tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
if
CPT
82784
Specimen volume
1-2 mL
Stability
Immediate analysis required, Refrigerated: 1h
Hemolysis max
200
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your healthcare provider may order CRP testing to check for signs of inflammation, monitor chronic conditions like rheumatoid arthritis or heart disease, or evaluate symptoms such as fever, joint pain, or unexplained swelling. It can also help determine if an infection is present or if your body is overreacting to an injury or illness.

What to Expect Before the Test

No special preparation is needed for this blood test. You may have a small needle inserted into your arm to draw a blood sample. If you’re taking blood from your own arm, follow your healthcare provider’s instructions for safety and comfort.

What Happens During the Test?

A healthcare professional will collect a small amount of blood from a vein in your arm. The blood will be sent to a lab for analysis. Results are typically available within a few days.

What Do the Results Mean?

CRP levels vary depending on your health. Higher levels often indicate inflammation, but they can also be influenced by factors like stress, recent illness, or certain medications. Your doctor will interpret the results in the context of your overall health and symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

CRP

Frequently asked questions

What causes elevated CRP levels?
Elevated CRP levels can be caused by infections (like pneumonia or urinary tract infections), autoimmune diseases (such as lupus or rheumatoid arthritis), heart disease, injuries, or certain medications. Chronic conditions like obesity or diabetes may also lead to higher baseline CRP levels.
What causes low CRP levels?
Low CRP levels are usually normal and don’t necessarily indicate a problem. However, very low levels might raise concerns if you have a history of inflammation or certain medical conditions. Your doctor will discuss this with you based on your health history.
Can CRP levels change over time?
Yes, CRP levels can fluctuate based on your health status, recent infections, or treatments. Regular monitoring may be needed if you have ongoing inflammation or a chronic condition. Follow-up tests can help track changes 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