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C-reactive protein (CRP) mass concentration in serum/plasma

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

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

Quick summary

["CRP helps doctors assess inflammation, often used to monitor conditions like infections, autoimmune diseases, or after surgery."]

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

Key facts at a glance

LOINC
13999-8
Short code
CDT
Synonyms
CDT SerPl-aCnc
Category
chemistry
Sample
serum
Container
Red-top serum tube (no anticoagulant) or serum separator tube (SST)
Units
N/A
Ref low
1.3
Ref high
1.6
Fasting
false
Population
adult
Sex
all
Age range
0–999 years
Method
Capillary electrophoresis, HPLC, or immunoassay-based methods (e.g., %CDT by HPLC or immunoassay)
CPT
82542 (Chromatography, quantitative)
SNOMED
269810008 | 167641000119103
Specimen volume
1-2 mL serum
Stability
Stable for 7 days at 2-8°C; for longer storage, freeze at -20°C or below. Avoid repeated freeze-thaw cycles.
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
24–96 hours
Order
routine

Why Is This Test Done?

Your doctor may order CRP testing to check for signs of inflammation, monitor chronic conditions like rheumatoid arthritis or lupus, evaluate infections, or assess recovery after surgery or injury. It can also help guide treatment decisions for certain heart or kidney conditions.

What Does a High CRP Level Mean?

Elevated CRP levels often indicate inflammation, which can be caused by infections, autoimmune diseases, or other health issues. However, a single high result doesn’t always mean a serious problem—your doctor will consider your overall health and other test results.

What Does a Low CRP Level Mean?

Low CRP levels usually suggest minimal inflammation. However, very low levels might not always mean no inflammation is present, especially in chronic conditions. Your doctor will interpret results in the context of your symptoms and other tests.

How Is This Test Performed?

A blood sample is drawn from a vein, usually in your arm. The blood is then sent to a lab where it is analyzed to measure CRP levels using a sensitive detection method.

Reference range

Reference values vary by method. Generally, CDT (carbohydrate-deficient transferrin) <1.3% is considered normal for non-heavy drinkers; values between 1.3-1.6% are borderline, and >1.6-2.0% suggest chronic alcohol consumption. Reportable in units/volume as measured concentration of asialo-, monosialo-, and disialo-transferrin isoforms.N/A

Specimen: serum

No special patient preparation required. Recent alcohol intake within 24-48 hours does not typically affect results; chronic consumption patterns (2-3 weeks of heavy drinking) are reflected. Patients should not be on total parenteral nutrition during testing when possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

CRP is a marker of inflammation and can reflect underlying health issues like infections, autoimmune diseases, or tissue damage. While it’s not diagnostic on its own, it helps doctors monitor disease activity, guide treatment, and assess recovery progress.

Short name

CRP

Frequently asked questions

What are the normal CRP levels?
There is no single ‘normal’ range for CRP because levels can vary widely based on health, age, and other factors. Your doctor will use your specific results along with your medical history and symptoms to determine what they mean for you.
How often should I get this test?
Your doctor will tell you how often to get this test based on your health needs. Some people may need CRP checked monthly, while others may only need it occasionally, depending on their condition and treatment plan.
Can diet or exercise affect CRP levels?
Yes, lifestyle factors like diet, exercise, and stress can influence CRP levels. Eating a healthy diet, staying active, and managing stress may help lower inflammation, but results can vary among individuals.
  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