C-reactive protein

C-reactive protein is a substance the liver pumps out when there is inflammation anywhere in the body — think of it as smoke that signals a fire somewhere, without pinpointing exactly where. A blood level rises within hours of injury, infection, or other inflammatory triggers.

In cardiology, a special high-sensitivity version of the test is used to detect the low-grade, smoldering inflammation that accompanies atherosclerosis. Because inflamed plaques are more prone to rupture and cause heart attacks, a modestly elevated high-sensitivity CRP in an otherwise stable person flags a somewhat higher cardiovascular risk.

CRP is not specific to the heart: it rises with any infection or inflammatory illness, which limits its usefulness as a standalone heart test. It is best used to refine risk in selected people, and emerging therapies that lower inflammation suggest this pathway is a genuine contributor to heart disease, not merely a bystander marker.