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C-reactive protein (CRP) concentration, serum/plasma

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 assess 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
22201-8
Short code
C trach G+F+K IgG Titr Ser
Synonyms
C trach G+F+K IgG Titr Ser
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
8
Ref high
61
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
82977
SNOMED
3110003
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 doctor may order a CRP test to check for signs of inflammation, monitor chronic conditions like arthritis or heart disease, or evaluate responses to treatments. It can also help identify infections or other inflammatory processes in your body.

What to Expect Before the Test

No special preparation is usually needed. You may be asked to fast for 8–12 hours before the test if serum/plasma is collected via venipuncture. If urine is involved, drinking water is often encouraged to help produce a sample.

How the Test Works

Blood is drawn from a vein in your arm, and the sample is analyzed to measure CRP levels. If a urine sample is used, it’s collected in a clean container and sent to the lab for testing.

Possible Results and Interpretation

Results are compared to a reference range, though exact values can vary by lab. Higher CRP levels often indicate inflammation, while lower levels may suggest reduced inflammation or no active condition.

Reference range

Adult males: 8-61 U/L; Adult females: 5-36 U/LN/A

Specimen: serum

No special preparation required. Avoid fatty meals before the test if possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

CRP is a marker for systemic inflammation. Elevated levels can signal infections, autoimmune diseases (like rheumatoid arthritis), heart disease, or other inflammatory conditions. It’s also used to monitor disease activity or treatment effectiveness in chronic illnesses.

Short name

CRP (Serum/Plasma)

Frequently asked questions

What Does a High CRP Level Mean?
A high CRP level may indicate inflammation or infection, prompting further testing to identify the cause. Your doctor will consider your symptoms, medical history, and other test results to interpret results accurately.
Can Diet or Exercise Affect CRP Levels?
Yes, lifestyle factors like diet, exercise, and smoking can influence CRP levels. Reducing inflammation through a healthy diet, regular physical activity, and avoiding smoking may help lower CRP levels over time.
Is CRP Test Painful?
The blood draw for a CRP test involves a small needle inserted into your arm, which may cause mild discomfort. Most people describe it as similar to a quick vaccine shot. If you’re anxious, let your doctor know to use a smaller needle or distraction techniques.
  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