hs CRP Test

The hs CRP test (high-sensitivity (HS) C-reactive protein (CRP) test) is a blood test that measures the level of C-reactive protein in your blood. The test is one way to determine the risk of heart disease. It can be used as a blood test for heart attack.

Cardio-Med offers the homocysteine test in addition to the hs CRP test for in-depth assessment of risk of heart disease.

What is being tested?

C-reactive protein (CRP) is a protein that increases in the blood with inflammation and infection as well as following a heart attack, surgery, or trauma. Thus, it is one of several proteins that are often referred to as acute phase reactants. The hs CRP test measures low levels of CRP in the blood to identify low levels of inflammation that may indicate a higher risk of heart disease.

There are two different blood tests that measure CRP, and each test measures a different range of CRP level in the blood for different purposes:

  • The standard hs CRP test measures markedly high levels of the protein to detect diseases that cause significant inflammation. It measures CRP in the range from 10 to 1000 mg/L.
  • The hs CRP test accurately detects lower levels of the protein than the standard hs CRP test and is used to evaluate individuals for risk of heart disease. It measures CRP in the range from 0.5 to 10 mg/L.

It is now believed that a persistently low level of inflammation plays a major role in atherosclerosis, the narrowing of the arteries due to build-up of cholesterol and other lipids associated with high risk of heart disease.

Heart disease causes more deaths in the U.S. each year than any other cause, according to the American Heart Association. A number of risk factors such as family history, high cholesterol, high blood pressure, obesity and diabetes have been linked to high risk of heart disease. But in addition a significant number of people who have few or no identified risk factors will also develop heart disease. This fact has lead researchers to look for additional risk factors that could be used to determine lifestyle changes or treatments to reduce the risk of heart disease.

CRP is one of a growing number of cardiac risk markers that are used to determine a person's risk. Some studies have shown that the hs CRP test can help identify the risk level of heart disease in apparently healthy people. This more sensitive test can measure CRP levels that are within the higher end of the reference range. These normal but slightly high levels of CRP in otherwise healthy individuals can predict the future risk of a heart attack, stroke, sudden cardiac death and peripheral arterial disease, even when cholesterol levels are within an acceptable range.

How is it used?

The hs CRP test may be used to help evaluate an individual for risk of heart disease. It may be used in combination with a lipid profile blood test such as offered by Cardio-Med. Other cardiac risk markers such as a lipoprotein-associated phospholipase A2 (Lp-PLA2) test provide added information about heart disease risk.

The hs CRP test accurately measures low levels of C-reactive protein to identify low but persistent levels of inflammation that help predict a person's risk of heart disease.

At Cardio-Med we recommend combining the hs CRP test with a lipid profile blood test. These tests can be used for people who have a moderate risk of heart attack.

What do the test results mean?

Relatively high levels of hs CRP in otherwise healthy individuals have been found to indicate an increased risk of a future heart attack, stroke, sudden cardiac death or peripheral arterial disease, even when cholesterol levels are within an acceptable range.

People with higher hs CRP values have a higher risk of heart disease and those with lower values have less risk. Specifically, individuals who have hs CRP results at the high end of the normal range have 1.5 to 4 times the risk of having a heart attack as those with hs CRP values at the low end of the normal range.

The American Heart Association and U.S. Centers for Disease Control and Prevention have defined risk groups as follows:

  • Low risk: less than 1.0 mg/L
  • Average risk: 1.0 to 3.0 mg/L
  • High risk: above 3.0 mg/L

These values are only a part of the total evaluation process for cardiovascular diseases. Additional risk factors to be considered are elevated levels of cholesterol, LDL-C, triglycerides, and glucose. In addition, smoking, high blood pressure (hypertension), and diabetes also increase the risk level.

Is there anything else I should know?

Taking nonsteroidal anti-inflammatory drugs (NSAIDs, e.g., aspirin, ibuprofen, and naproxen) or statins may reduce CRP levels in blood. Both anti-inflammatory drugs and statins may help to reduce inflammation, thus reducing CRP.

It is important that any person having this test be in a healthy state for the results to be of value in predicting the risk of coronary disease or heart attack. Any recent illness, tissue injury, infection, or other general inflammation will raise the amount of CRP and give a falsely elevated estimate of risk.

Women on hormone replacement therapy have been shown to have elevated hs CRP levels.

Since the hs CRP test and standard hs CRP test measure the same protein, people with chronic inflammation, such as those with arthritis, should not have hs-CRP levels measured. Their CRP levels will already be very high due to arthritis, so results of the hs-CRP test will not be meaningful.

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Adapted from the American Association for Clinical Chemistry