What is a C blood test?

What Is a C-Reactive Protein (CRP)?

The c-reactive protein (CRP) test measures the level of C-reactive protein in your blood. C-reactive protein is a substance made by your liver in response to inflammation. CRP levels usually rise within a few hours of the start of inflammation. CRP is a marker for systemic inflammation that is commonly measured in clinical practice to assess the body’s total inflammatory burden and to aid in the evaluation and management of certain infections and inflammatory conditions.

High levels of C-reactive protein may be a sign of inflammation, infection, or tissue damage. CRP levels can be increased by a variety of conditions, including:

Infection: CRP levels can be increased by any type of infection, including bacterial, viral, and fungal infections.

Inflammation: CRP levels can be increased by any type of inflammation, including inflammatory diseases (such as arthritis and Crohn's disease), injuries, and burns.

Trauma: CRP levels can be increased by any type of trauma, including surgery and car accidents.

Cancer: CRP levels can be increased by some types of cancer, including lung cancer, colon cancer, and breast cancer.

Normal CRP levels are usually less than 10 milligrams per liter (mg/L). Values greater than 10 mg/L are considered to be high. However, the specific interpretation of CRP levels may vary depending on the individual's medical condition and the reason for the test.

Why Is a C-Reactive Protein (CRP) Test Performed?

A C-reactive protein (CRP) test may be performed to:

- Help diagnose an infection or inflammatory condition

- Monitor the severity of an infection or inflammatory condition

- Assess the risk of developing cardiovascular disease

- Monitor the effectiveness of treatment for an infection or inflammatory condition

- Rule out other possible causes of symptoms, such as autoimmune diseases, cancer, or trauma.

Your doctor may recommend a CRP test if you have symptoms of an infection, such as fever, chills, or body aches. A CRP test may also be recommended if you have a known inflammatory condition, such as arthritis or Crohn's disease, to monitor the activity of the disease. In some cases, a CRP test may be recommended as part of a routine health screening to assess your risk of developing cardiovascular disease.

How Is a C-Reactive Protein (CRP) Test Performed?

A CRP test is a blood test. A blood sample is drawn from a vein in your arm and sent to a laboratory for analysis.

The blood sample is typically collected after you have fasted for 8-12 hours. This means avoiding food and drink, except for water, for the specified period before the test.

How Should I Prepare for a C-Reactive Protein (CRP) Test?

You should fast for 8-12 hours before your CRP test. This means avoiding food and drink, except for water, for the specified period before the test.

You should also tell your doctor about any medications you are taking, as some medications can interfere with CRP levels.

What Are the Risks of a C-Reactive Protein (CRP) Test?

A CRP test is a low-risk procedure. The most common risk is bruising or pain at the injection site.

What Do the Results of a C-Reactive Protein (CRP) Test Mean?

The results of a CRP test are reported in milligrams per liter (mg/L). Normal CRP levels are usually less than 10 mg/L. Values greater than 10 mg/L are considered to be high.

The specific interpretation of CRP levels may vary depending on the individual's medical condition and the reason for the test.

High CRP levels may indicate:

Infection

Inflammation

Tissue damage

Cancer

Low CRP levels may indicate a low risk of developing cardiovascular disease. However, a normal CRP level does not rule out the possibility of an infection or inflammatory condition.

If your CRP levels are high, your doctor may order additional tests to determine the cause of the elevated levels.

What Are the Limitations of a C-Reactive Protein (CRP) Test?

The CRP test is not specific for any particular condition. High CRP levels can be caused by a variety of conditions, including infection, inflammation, and tissue damage.

A normal CRP level does not rule out the possibility of an infection or inflammatory condition. Some infections, such as viral infections, may not cause a significant increase in CRP levels.

The CRP test is also not a reliable indicator of the severity of an infection or inflammatory condition. Some conditions, such as sepsis, can cause life-threatening infections even with normal CRP levels.

CRP levels can also be affected by a number of factors, including:

Age

Sex

Smoking

Obesity

Pregnancy

Certain medications

For these reasons, it is important to interpret CRP levels in the context of a person's individual medical history and symptoms.