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

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

This test measures the level of C-reactive protein, a protein produced by the liver in response to inflammation.

Quick summary

["CRP helps identify and monitor inflammation in your body."]

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

Key facts at a glance

LOINC
71886-6
Short code
COHgb MFr.DF BldCoV
Synonyms
COHgb MFr.DF BldCoV
Category
hematology
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Ref low
12
Ref high
17.5
Critical range
7 N/A – 20 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
85018
SNOMED
900000000000003004
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your healthcare provider may order this test to check for signs of inflammation, monitor conditions like infections, autoimmune diseases, or after surgery. It can also help assess risk for heart disease or other inflammatory conditions.

What Does a High or Low CRP Level Mean?

Elevated CRP levels often indicate inflammation, which can be due to infections, injuries, or certain medical conditions. Very low levels may suggest a lack of inflammation, though this isn’t always the case and can depend on other factors like age or medications.

How Is the Test Performed?

A blood sample is taken from a vein, usually in your arm. The blood is then processed to separate serum or plasma, which is sent to a lab for analysis using nephelometry, a method that measures how particles scatter light to detect protein levels.

What Should You Do Before the Test?

Avoid strenuous exercise or consuming very large meals 24 hours before the test, as these can temporarily affect CRP levels. Inform your provider about any medications or supplements you’re taking.

Reference range

Adult males: 13.5-17.5 g/dL; Females: 12.0-16.0 g/dLN/A

Specimen: whole-blood

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.

◆Associated findings1

Short name

CRP (Nephelometry)

Frequently asked questions

How soon will I get my results?
Results are typically available within 1 to 3 business days, depending on lab processing times. Your provider will discuss the results with you during your follow-up visit.
Can I eat or drink anything before this test?
You can eat and drink normally unless instructed otherwise. Avoid heavy meals or intense physical activity 24 hours before the test, as these can influence CRP levels.
Does this test require fasting?
No fasting is required for this test. However, if you have questions about timing or preparation, always follow your healthcare provider’s instructions.
  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