Harvard Heart Letter

Bringing clarity to CRP testing

Wider use is in the offing for this simple blood test to gauge cardiac risk.

It isn't easy to gauge the health of the heart and arteries. Blood pressure and cholesterol are good stand-ins, but they aren't perfect. That's why researchers have explored hundreds of other tests. The one that has edged closest to widespread use is a blood test for C-reactive protein (CRP). An excess of CRP in the bloodstream signals the kind of steady, low-grade inflammation that accompanies artery-clogging atherosclerosis, a key contributor to cardiovascular disease. The test is called the high-sensitivity C-reactive protein (hsCRP) or cardiac CRP test. It defines three categories of risk (see table).

C-reactive protein and cardiovascular risk

CRP level

Cardiovascular risk

Below 1 mg/dL

Low

1–3 mg/dL

Moderate

Above 3 mg/dL

High

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