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C-reactive protein (CRP) is a substance the liver produces in response to inflammation.

A high level of CRP in the blood can be a marker of inflammation. A wide variety of conditions can cause it, from an infection to cancer.

High CRP levels can also indicate that there’s inflammation in the arteries of the heart, which can mean a higher risk of heart attack.

However, the CRP test is an extremely nonspecific test. CRP levels can be elevated in many inflammatory conditions.

If your doctor suspects you may have an inflammatory disorder (like arthritis, cancer, an infection, etc.), they may order a C-reaction protein test. This test can show there’s a high level of inflammation, but it does not show where the inflammation is located or what might be causing it.

If you have a previously diagnosed inflammatory issue, your doctor may also order this test occasionally to see how your treatment is working, and if the issue is being properly managed.

It’s important to note that ahigh-sensitivity C-reactive protein (hs-CRP) test is a slightly different test than a regular C-reaction protein test. This test typically predicts heart disease and stroke.

While the regular C-reactive test can help uncover different diseases that cause inflammation by measuring high levels of protein, the hs-CRP test measures lower (but still elevated) levels of protein, which can signal the risk of heart disease and stroke.

Your doctor may order a hs-CRP if they’re focusing on cardiovascular issues.

CRP and heart disease

Expert opinion from the American Heart Association in 2019 states that when considering all risk factors, people with CRP levels greater than or equal to 2 milligrams per liter (mg/L) may need more intense measures to prevent cardiovascular disease.

Elevated levels of CRP may have an important role in identifying people who might need closer follow-up or more intensive treatment after heart attacks or heart procedures.

CRP levels may also be useful in identifying people at risk of heart disease when cholesterol levels alone may not be helpful.

The Centers for Disease Control and Prevention (CDC) considers the following as significant risk factors for developing heart disease:

A family history of heart disease can also put you at a higher risk of heart disease.

No special preparation is necessary for this test. You may eat normally on the day of, and the test can happen at any time of day.

This test is done via a blood sample, so there will be a small needle involved.

A nurse or other healthcare professional will draw blood from a vein, usually on the inside of your elbow or the back of your hand.

First, they clean the skin over the vein with antiseptic. Next, they wrap an elastic band around your arm, causing your veins to bulge out slightly. The healthcare professional then inserts a small needle into the vein and collects your blood in a sterile vial.

After the healthcare professional collects your blood sample, they remove the elastic band around your arm and ask you to apply pressure to the puncture site with gauze. They may use tape or a bandage to hold the gauze in place.

Are there risks with the test?

There are no risks associated with this test other than routine issues that can occur with any blood test. The main issues include:

  • a slight pinch when the needle is inserted
  • slight bruising at needle insertion site

If you’re nervous around needles or blood, talk with the healthcare professional administering the test about ways to make it more comfortable for you.

In general, the results of your test will be measured in either mg/dL or mg/L.

Your doctor will most likely explain the results of your test to you, but in general:

  • A typical result: Less than 10 mg/L
  • A high result: Equal to or greater than 10 mg/L

According to a 2003 study by the American Heart Association, people with a higher level of CRP were two to three times more likely to have a heart attack than people with lower levels of CRP.

A small study from 2013 evaluated 100 people with cardiovascular risk factors. Researchers found that a CRP level over 10 mg/L was connected to a 4 percent risk of developing a fatal cardiovascular disease in 10 years.

If your doctor believes you may be at risk of heart disease or stroke, they may order a hs-CRP blood test alongside other tests.

Additionally, there’s more recent research that suggests CRP may be used as a predictor of health outcomes related to chronic obstructive pulmonary disease (COPD).

If your doctor is concerned you are dealing with the symptoms of other inflammatory conditions besides cardiovascular issues, they may order a regular CRP test to diagnose, among other things:

Lowering your CRP isn’t a guaranteed way to lower your risk of cardiovascular or autoimmune disease.

It’s important to know that high CRP is what doctors call a biomarker. A biomarker is a factor to keep in mind when analyzing a person’s health, but not a stand-alone indicator of a particular diagnosis.

A 2015 study indicates that eating a nutritious, balanced diet — including lots of fruits, vegetables, and fiber — may help lower your CRP concentration.

If you’re at high risk of cardiovascular disease and your test results show high CRP, your doctor may suggest a statin or other cholesterol-lowering medication.

Vitamin C has also been explored as a way to lower CRP levels for people who have an elevated risk of cardiovascular disease.

A 2017 research review suggests that probiotics may also have a positive effect in lowering CRP.

However, more studies have to be done for each method before any definitive claims can be made.

C-reactive protein (CRP) is a substance the liver produces in response to inflammation.

If your doctor suspects you may have a high level of inflammation, they may order a CRP blood test as one way to identify the underlying cause of that inflammation.

While a CRP blood test can’t say what exactly is causing your inflammation, your doctor may be able to use it to help them diagnose your issue.

Sometimes a high CRP measurement can be a risk factor for cardiovascular disease.

If you’ve recently noticed changes in your body that aren’t going away and causing you discomfort, talk with your doctor about your symptoms. A CRP blood test may be one of the tests your doctor decides to order.