What is hs-CRP and why do cardiologists care about it?

High-sensitivity C-reactive protein is an inflammation marker produced by the liver in response to inflammatory signaling throughout the body. The "high sensitivity" refers to the assay calibration: standard CRP tests are designed for the acute illness range of 10–100+ mg/L. The hs-CRP assay is calibrated for the 0–5 mg/L range where cardiovascular risk lives.

Cardiologists care about hs-CRP because it predicts cardiovascular events independently of LDL cholesterol. In the JUPITER trial, men with LDL below 130 mg/dL but hs-CRP above 2.0 mg/L had a 44% reduction in major adverse cardiovascular events with statin therapy, confirming that inflammation is not a secondary finding but a primary driver of cardiac events. The man with an LDL of 110 and an hs-CRP of 3.8 mg/L is not cardiovascularly safe. His inflammatory burden poses cardiac risk independent of his lipid numbers, a risk that his annual physical will not calculate unless hs-CRP was ordered. (Ridker et al., NEJM, 2008)

Cardiologist's calibrated position, Solid (1). hs-CRP as an independent cardiovascular risk predictor beyond LDL has robust evidence from multiple large prospective cohort studies and the JUPITER RCT.

What to do: Order hs-CRP on your next blood draw. Cost at direct-to-consumer labs: under $30. Interpret below 1.0 mg/L as low cardiovascular inflammation risk, 1.0–3.0 mg/L as intermediate, above 3.0 mg/L as high.

For the full picture, read Inflammation's Invoice.