C-reactive protein

What is C-reactive protein (CRP)?

C-reactive protein (CRP) is a protein that is produced in the liver. It’s released into your bloodstream when there’s inflammation in your body. The amount of CRP in your bloodstream can be measured with a simple blood test.

Types of C-reactive protein tests

There are two primary tests used to measure CRP levels: the high-sensitivity CRP (hs-CRP) test and the traditional CRP test. The hs-CRP test is more sensitive than the traditional CRP test and can detect lower levels of inflammation in the body. The traditional CRP test is used to measure levels of inflammation that are higher than that detected by the hs-CRP test.

Why a C-reactive protein test is done

A CRP test is typically done to measure the amount of inflammation in the body. It can help a doctor diagnose and treat conditions that cause inflammation such as:

  • heart disease
  • arthritis
  • cancer
  • lupus
  • inflammatory bowel disease (IBD)

It can also help a doctor monitor the effects of treatment for conditions that cause inflammation.

When a C-reactive protein test is done

A CRP test is typically done when a doctor suspects that a person has an inflammation-related disorder. It’s often part of a larger health screening. A CRP test may be done as part of a routine physical exam or when a person has symptoms such as fever, joint pain, or abdominal pain.

Risks of a C-reactive protein Test

A CRP test is generally considered safe. The risks are minimal, but may include:

  • slight bleeding from the needle prick
  • blood accumulation under the skin (hematoma)
  • bruising around the area where the needle was inserted
  • fainting or feeling lightheaded
  • infection at the injection site

Preparation for C-reactive protein Test

You may need to take pre-test preparation steps depending on the type of test. Generally,a CRP test does not involve any specific preparation. You may need to fast for a few hours before the test or stop taking certain medications that can alter your lab results. Your doctor will tell you what preparations, if any, are necessary and provide instructions.

C-reactive Protein (CRP) Test Procedure

A CRP test involves a simple blood draw. Your doctor or a trained technician will insert a needle into a vein, usually in your arm or hand. Blood will be collected in a vial or syringe. The technician will then send it to a lab for testing.

C-reactive Protein Test Results

Normal levels of CRP range from 0 to 10 milligrams per liter (mg/L). Levels higher than 10 mg/L indicate that inflammation is present in your body. Your doctor will use your CRP test results, along with other tests and medical history, to diagnose and treat any underlying conditions.