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C-reactive protein (CRP) concentration in plasma

Published: August 9, 2026Updated: August 17, 2026

This test measures the level of C-reactive protein, a protein made by your liver in response to inflammation or infection in your body.

Quick summary

["CRP helps doctors track inflammation, infection, or other health issues."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
111859-5
Short code
Insertion route Endscpy
Synonyms
Insertion route Endscpy
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
0
Ref high
17
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
endoscopy
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 this test to check for signs of inflammation, infection, or other conditions like autoimmune diseases, heart disease, or kidney problems. It can also help monitor treatment progress for certain conditions.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm or vein to draw blood. If you’re on blood thinners, tell your doctor before the test.

What the Test Results Mean

Higher CRP levels often indicate inflammation or infection, but results alone don’t diagnose a specific condition. Your doctor will review your results with other tests and symptoms.

Common Conditions Monitored

This test is often used to monitor conditions like rheumatoid arthritis, lupus, heart disease, or infections such as pneumonia or sepsis.

Reference range

NCBI: NSE 0-17 ng/mLN/A

Specimen: serum

No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

CRP is a general marker for inflammation and can help guide treatment decisions, but it’s not definitive on its own. Elevated levels may prompt further testing to identify the cause.

Short name

CRP Plasma

Frequently asked questions

Why might my CRP level be higher than expected?
Several factors can raise CRP, including infections, injuries, autoimmune diseases, or certain medications. Stress, smoking, or obesity may also influence results.
What should I do if my CRP test is abnormal?
If your CRP is elevated, your doctor may recommend additional tests (like blood cultures or imaging) to find the cause of inflammation. Follow their advice for next steps.
Can diet or lifestyle changes affect CRP levels?
Yes, diet, exercise, weight management, and avoiding smoking can help lower CRP levels. Ask your doctor about strategies tailored to your health goals.
  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 17, 2026. · Read our editorial policy