At a glance

Why get tested?

May be used to help predict your risk of developing heart disease

When to get tested?

Currently there is no agreement on whether to or when to get tested

Most often ordered when risk factors for heart and blood vessel disease are present, as part of a cardiac risk assessment (assessing your risk of heart disease).

Sample required?

A blood sample drawn from a vein in your arm.

A minimum of two tests need to be done and the lowest value or the average taken as the baseline to estimate risk as levels vary over time in individuals.

Test preparation needed?

Test not to be performed if patient acutely unwell, or recent illnesses, infection, inflammation, or tissue injury

What is being tested?

C-reactive protein (CRP) is a protein in the blood that increases when inflammation is present. CRP has been used for many years as an indicator of infection and inflammation associated with disease. Doctors now believe that atherosclerosis (fatty build-up in artery walls, also called 'hardening of the arteries') is also an inflammatory process. However, the inflammation from atherosclerosis is a low level of long-term inflammation that produces only small amounts of CRP. Therefore, the test requires higher sensitivity than previous tests in order to detect the small increases of CRP. Thus, this test is known as high-sensitivity CRP or hs-CRP.

How is the sample collected for testing?

A blood sample is drawn by needle from a vein in your arm.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed but you must be completely well at the time the test is done.

The Test

How is it used?

hs-CRP is being proposed as a method for predicting a healthy person’s individual risk of a heart attack or other heart conditions.

If your hs-CRP level is on the high end of the normal range, it may be a sign that you are at risk for cardiovascular (heart and blood vessel) disease and other heart conditions. People who seem to be healthy but who have hs-CRP results in the highest quarter of test results have 2 to 4 times the risk of developing blocked arteries, compared with those in the lowest quarter.

The CRP molecule itself is not a harmful molecule in the body. The higher level of CRP is simply a sign of higher than normal inflammation. Because half of heart attacks and strokes happen in patients who do not have elevated levels of cholesterol, measurement of hs-CRP may help doctors identify patients who are at increased risk and therefore may benefit from medical treatment.

When is it requested?

Currently, there is no agreement about exactly when the test should be used, and who should have this test. There is not yet a consensus about its value, but the test is being promoted by some as a test to help cardiologists assess risk for acute coronary syndrome (clogged blood vessels around the heart).

hs-CRP is usually requested as one of several tests for a cardiovascular risk profile, often along with lipid (fat) tests, like the various tests for cholesterol and triglycerides. Some experts say that the best way to predict risk is to combine a good marker for inflammation, like CRP, along with the ratio of total cholesterol to HDL cholesterol.

Currently there are some guidelines that recommend using hs-CRP as a test in screening for cardiovascular risk in certain groups of patients. Recent studies have shown, however, that the hs-CRP test may be useful in identifying risk in healthy individuals as well as in people who have symptoms of chest pain. This is difficult to implement in practice because of the need to be tested on several occasions.

What does the test result mean?

The results are generally interpreted on a relative scale. People with the highest values have the highest risk of heart disease and those with the lowest values have the lowest risk. This is often expressed in quintiles (five divisions) with those in the top fifth (the highest 20%) having risk of heart disease about twice that of those in the bottom fifth (lowest 20%).

About Reference Intervals

Is there anything else I should know?

Relatively few Australian laboratories perform the hs-CRP currently and not all labs have the ability to do it.

Taking aspirin or statins (cholesterol-lowering drugs) may reduce CRP levels in blood. Both aspirin and statins may help to reduce the inflammation linked to the atherosclerotic process. Other drugs, such as nonsteroidal anti-inflammatory drugs (for example ibuprofen) and glucocorticoid drugs, may also lower CRP levels.

As hs-CRP tests measure a marker for inflammation, 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. Doctors need to know about recent medical events that may also have increased CRP levels, such as tissue injury, infections, or chronic inflammation (e.g. arthritis).

hs-CRP and CRP tests measure levels of the same molecule. The hs-CRP test is designed to measure lower levels of the molecule. People with chronic inflammation, such as those with arthritis and some other chronic illnesses e.g. inflammatory bowel disease and other autoimmune diseases, should not have hs-CRP levels measured because their results can’t be considered in the context of heart disease. Their CRP levels would be very high - too high for hs-CRP to be measured meaningfully.

Common Questions

I feel fine. Why do I need to take tests like hs-CRP for heart disease?

Heart attack and stroke can happen when you least expect it. You may not have any symptoms and still be at risk. Your doctor needs to collect information to get a good idea of your risk for heart attack and stroke. This might include cholesterol and other lipid tests, as well as an hs-CRP test.

I have had cholesterol tests, but never an hs-CRP test. Why?

The hs-CRP test is fairly new, and many labs don’t perform this test yet. Experts still don’t agree on whether/or how often this test should be ordered for a healthy population.

What is the difference between regular CRP and hs-CRP tests?

Both tests measure the same molecule in the blood. The hs-CRP is for seemingly healthy people who may be at risk for heart problems. The CRP test is requested for patients with inflammation, who may need to be monitored for conditions such as rheumatoid arthritis.

Last Review Date: May 1, 2018