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C-reactive protein (CRP) by nephelometry

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

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

Quick summary

["High CRP levels may signal inflammation needing further medical evaluation."]

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

Key facts at a glance

LOINC
11910-7
Short code
GA from CRL.Hadlock92
Synonyms
GA from CRL.Hadlock92
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
22
Ref high
198
Critical range
— – 10000 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
us-estimated-from-crl-hadlock
CPT
82553
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 conditions like rheumatoid arthritis, heart disease, or infections. High-sensitivity CRP helps detect mild inflammation that standard tests might miss.

What Does a High or Low Level Mean?

Elevated CRP levels often indicate inflammation, but they can also be normal if you have recent trauma, infection, or other triggers. Low levels may suggest reduced inflammation, but this isn’t always cause for concern without clinical context.

How Is the Sample Collected?

A blood sample is drawn from a vein, usually in your arm. You may feel a brief pinch, but it’s typically over quickly. No special preparation is needed unless instructed otherwise.

What Are Common Causes of Abnormal Results?

Increased CRP can result from infections, autoimmune diseases, or chronic conditions like heart disease. Decreased CRP might occur with certain medications or in very young children, but this varies by individual.

Reference range

Adult males: 22-198 U/L; Females: 22-198 U/LN/A

Specimen: serum

For females: inform if menstrual cycle status. For certain tests, timing within menstrual cycle may matter.

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 CRP test measure?
CRP measures the concentration of C-reactive protein in your blood, a protein produced by your liver in response to inflammation or infection.
How long does it take to get results?
Results are typically available within 24 to 48 hours, depending on your lab’s processing time.
Can I eat or drink before this test?
No special diet or fasting is required for this test, but follow any specific instructions your doctor provides.
  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