C-reactive protein (CRP) is a protein that increases in blood levels during inflammation and infection as well as during heart attacks, surgery, or trauma. Studies have shown that low, steady levels of inflammation play an important role in atherosclerosis, the narrowing of blood vessels caused by elevated cholesterol and other lipids.

The hs-CRP test is used to measure acute phase reactant protein. This biomarker has been associated with increased rates of cardiovascular events as well as hypertension, arterial stiffness, and plaque rupture.