hs-CRP

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

If your hs-CRP result is at the high end of the normal range, it may suggest that you are at risk of developing 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 marker of higher than normal inflammation. Because half of heart attacks and strokes happen in patients who do not have high levels of fat in their blood, measurement of hs-CRP may help doctors identify patients who are at risk and may need medical treatment to reduce your risk of developing vascular disease.

Unfortunately, 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). Some doctors use the test to assist with making the decision whether to prescribe lipid lowering medication to reduce vascular risk. Where the decision has already been made to commence lipid lowering treatment, there may be little to be gained by measuring hs-CRP.

hs-CRP may be 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 no official guidelines on using hs-CRP as a test in screening for cardiovascular risk. 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 not current UK practice.

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%).

If you're having an hs-CRP test to evaluate your risk of heart disease, current risk levels used include:

Lower risk. You have an hs-CRP level of less than 2.0 milligram per litre (mg/L).

Higher risk. You have an hs-CRP level greater than 2.0 mg/L.

These risk levels aren't a definitive measure of your risk because the ideal indicator of high CRP isn't clearly defined. Also, because a person's CRP levels vary over time, it's recommended that the average of two tests, ideally taken two weeks apart, be used to determine coronary artery disease risk.

Currently, relatively few UK laboratories perform the hs-CRP blood test and not all laboratories have the ability to do it.

Taking aspirin or pravastatin (a cholesterol-lowering drug) may reduce CRP levels in blood. Both aspirin and pravastatin 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 the concentration of CRP in the bloodstream.

Because hs-CRP tests measure a marker for inflammation, doctors need to know about recent medical events that may also have increased CRP levels, such as recent surgery, tissue injury, infections, or general inflammation, from conditions like 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 inflammation, such as those with arthritis or infections should not have hs-CRP levels measured because their results cannot be considered in the context of heart disease. Their CRP levels would be very high—too high for hs-CRP to be measured meaningfully.

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 assess your risk for heart attack and stroke. This might include cholesterol and other lipid tests, as well as an hs-CRP test.