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High-Sensitivity C-Reactive Protein

Test Overview

The high-sensitivity C-reactive protein (hs-CRP) test is a blood test that finds lower levels of C-reactive protein (CRP). This protein measures general levels of inflammation in your body. The hs-CRP can be used to find the risk for heart disease and stroke in people who don't already have heart disease. It can also be used to help predict how well a person who has heart disease might recover or to predict how the person might respond to treatment.

The hs-CRP test is different than the standard CRP test. The standard test measures high levels of the protein to find different diseases that cause inflammation. The hs-CRP test measures low levels and focuses on the risk of heart disease and stroke.

Why It Is Done

The hs-CRP test may be used to help assess the risk of a heart attack and stroke.

The results can help you and your doctor make decisions about how to lower your risk. The connection between hs-CRP levels and the risk of heart attack and stroke are not understood completely. But high levels may mean that the lining of your arteries is inflamed. This may damage the arteries and raise your risk of a heart attack and stroke.

How To Prepare

There is no special preparation for an hs-CRP test. You might be asked to not eat or drink for a few hours before the test.

Be sure to tell your doctor about all the medicines you take, even over-the-counter ones. Many medicines can change the results of this test.

Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form .

How It Is Done

The health professional taking a sample of your blood will:

  • Wrap an elastic band around your upper arm to stop the flow of blood. This makes the veins below the band larger so it is easier to put a needle into the vein.
  • Clean the needle site with alcohol.
  • Put the needle into the vein. More than one needle stick may be needed.
  • Attach a tube to the needle to fill it with blood.
  • Remove the band from your arm when enough blood is collected.
  • Put a gauze pad or cotton ball over the needle site as the needle is removed.
  • Put pressure on the site and then put on a bandage.

How It Feels

The blood sample is taken from a vein in your arm. An elastic band is wrapped around your upper arm. It may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.


There is very little chance of a problem from having a blood sample taken from a vein.

  • You may get a small bruise at the site. You can lower the chance of bruising by keeping pressure on the site for several minutes.
  • In rare cases, the vein may become swollen after the blood sample is taken. This problem is called phlebitis. You can use a warm compress several times a day to treat this.


The high-sensitivity C-reactive protein (hs-CRP) test is a blood test that looks at the lower levels of C-reactive protein (CRP).

The hs-CRP can be used to help show a person's risk for heart disease and stroke. Experts have defined the risk groups as follows:

  • Low risk: less than 1.0 milligrams per litre (mg/L).
  • Average risk: 1.0 to 3.0 mg/L.
  • High risk: above 3.0 mg/L.

What Affects the Test

You may not be able to have the test, or the results may not be helpful, if:

  • You take non-steroidal anti-inflammatory drugs (NSAIDs).
  • You recently had an illness, a tissue injury, an infection, or other general inflammation.
  • You have been on hormone therapy.
  • You have chronic inflammation, such as arthritis.

Taking statins can also affect the results of the test.

What To Think About

This test is not used on its own to assess a person's risk. It may help find your risk of heart problems, especially when it is considered along with other risk factors such as cholesterol, age, blood pressure, and smoking. Or it may be done to find out if you have a higher chance of having a sudden heart problem, such as a heart attack or a stroke. But the connection between high hs-CRP levels and heart disease risk is not understood very well.


Current as of:
August 31, 2020

Author: Healthwise Staff
Medical Review:
Adam Husney MD - Family Medicine
Brian D. O'Brien MD - Internal Medicine
Martin J. Gabica MD - Family Medicine
E. Gregory Thompson MD - Internal Medicine
Stephen Fort MD, MRCP, FRCPC - Interventional Cardiology