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C-reactive protein (CRP) by turbidimetry in serum/plasma

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

This test measures a protein your body produces in response to inflammation, often used to check for signs of infection, injury, or other inflammatory conditions.

Quick summary

["Helps detect 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
88221-7
Short code
C trach DNA Throat Ql NAA+probe
Synonyms
C trach DNA Throat 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 It’s Done

Your doctor may order this test to monitor conditions like arthritis, heart disease, or infections, or to check for inflammation after surgery, trauma, or other medical events. High-sensitivity CRP is particularly useful for detecting low-level inflammation that could indicate early disease, such as cardiovascular risk.

What to Expect

A small blood sample is taken from a vein in your arm. You may feel a slight pinch, but it usually doesn’t cause much discomfort. The blood is sent to a lab where it’s analyzed for CRP levels.

How It Works

The test uses a method called turbidimetry, which measures how much light scatters when CRP proteins interact with a chemical reaction in the sample. Higher CRP levels mean more scattering, indicating more inflammation.

What the Results Mean

Results are typically reported in milligrams per liter (mg/L). While reference ranges vary by lab, very high levels may suggest severe inflammation, while very low levels might indicate no active inflammation. Your doctor will interpret results in the context of your overall health and symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP (High-Sensitivity)

Frequently asked questions

What does my CRP level tell me about my health?
CRP levels help doctors assess inflammation, which can signal conditions like infections, autoimmune diseases, or chronic inflammation. For example, elevated CRP may prompt further testing for conditions like rheumatoid arthritis or heart disease. Low levels usually mean no significant inflammation is present, but they don’t rule out all causes of illness.
How often should I get this test?
Your doctor will determine how often you need this test based on your medical history, symptoms, and treatment plan. Some people may need it yearly or more frequently if they have ongoing health concerns like heart disease or arthritis.
Can lifestyle changes affect CRP levels?
Yes! Lifestyle factors like diet, exercise, smoking, and stress can influence CRP levels. Eating a heart-healthy diet, staying active, and avoiding smoking may help lower CRP and reduce inflammation 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