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C-reactive protein (CRP) by high-performance liquid chromatography (HPLC) in plasma

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

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

Quick summary

["CRP helps doctors track inflammation, often used to check for infections or other health issues."]

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

Key facts at a glance

LOINC
21613-5
Short code
C trach DNA Spec Ql NAA+probe
Synonyms
C trach DNA Spec Ql NAA+probe
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
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 monitor inflammation, check for infections (like pneumonia or sepsis), evaluate conditions like rheumatoid arthritis, or assess heart disease risk. It can also help guide treatment decisions for conditions like autoimmune diseases or after surgery.

What Does a High or Low Level Mean?

Elevated CRP levels often indicate inflammation or infection, while very low levels may suggest no active inflammation. However, results alone don’t diagnose a condition—they’re used alongside other tests and symptoms.

Sample Collection and Preparation

A blood sample is drawn from a vein, usually in your arm. The blood is processed to separate plasma, which is then analyzed using HPLC to measure CRP levels precisely.

Common Causes of Abnormal Results

Infections (bacterial, viral), injuries, surgeries, autoimmune diseases (like lupus or rheumatoid arthritis), heart disease, or certain medications can raise CRP. Smoking, obesity, or stress may also influence results.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP (Plasma)

Frequently asked questions

Can CRP levels predict future health problems?
Yes, CRP is sometimes used as a marker for long-term inflammation risk, such as cardiovascular disease. High baseline CRP may signal increased risk, prompting further evaluation.
Is CRP the same as a white blood cell count?
No, CRP is a protein that rises with inflammation, while white blood cell counts measure immune cells. Both are useful but serve different purposes in diagnosing conditions.
How often should I get this test?
Your doctor will determine frequency based on your health needs—some patients get it yearly, while others may need it more often if managing chronic conditions like heart disease or arthritis.
  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