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C-reactive protein (CRP) in serum/plasma by high-performance liquid chromatography (HPLC) or immunoassay (clia/fia)

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

This test measures a protein produced by your liver in response to inflammation, helping detect or monitor low-to-moderate levels of inflammation in your body.

Quick summary

["CRP helps track subtle inflammation that may not show up in other tests."]

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

Key facts at a glance

LOINC
51578-3
Short code
C trach DNA Smn Ql NAA+probe
Synonyms
C trach DNA Smn 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 CRP tested?

Doctors may order this test to check for early signs of inflammation, monitor conditions like heart disease, autoimmune disorders, or infections, or assess response to treatment. High sensitivity CRP is often used when standard CRP levels are too low to detect inflammation reliably.

What does CRP measure?

CRP is a marker for inflammation. Your body produces it when tissues are injured or infected. While CRP itself doesn’t cause inflammation, it signals the presence of inflammation by increasing in your bloodstream.

How is CRP tested?

A blood sample is taken from a vein in your arm. The sample is sent to a lab where it’s analyzed using either high-performance liquid chromatography (HPLC) or a sensitive immunoassay method to detect CRP levels.

What might affect CRP levels?

Several factors can influence CRP levels, including infections (like colds or flu), injuries, surgeries, or medical conditions like heart disease, arthritis, or certain cancers. Stress, smoking, and certain medications can also affect results.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP (High Sensitivity)

Frequently asked questions

What does a high CRP level mean?
A high CRP level suggests inflammation is present in your body, which could be due to infections, autoimmune diseases, or other inflammatory conditions. However, CRP alone isn’t diagnostic—it’s often used alongside other tests and symptoms to guide treatment decisions.
What does a low CRP level mean?
A low CRP level usually means there’s little to no inflammation detected in your blood. However, it’s important to note that CRP can be low in some healthy individuals or those with very mild inflammation, so results should be interpreted by your healthcare provider.
How often should CRP be checked?
Your doctor will determine how often you need CRP testing based on your health condition, symptoms, and treatment plan. Regular monitoring may be necessary for conditions like heart disease or autoimmune disorders.
  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