In short
hs-CRP (high-sensitivity C-reactive protein) is a blood test that measures C-reactive protein at a much lower detection threshold than a standard CRP test, allowing it to detect the low-grade, chronic inflammation associated with cardiovascular risk rather than only acute infection.
C-reactive protein is produced by the liver in response to interleukin-6 and other inflammatory signals, rising sharply (often 100-fold or more) during acute infection or injury. The high-sensitivity assay is designed to reliably quantify CRP in the much lower range relevant to chronic, low-grade inflammation — typically reported in categories of low risk (below 1.0 mg/L), average risk (1.0–3.0 mg/L), and high risk (above 3.0 mg/L) for cardiovascular disease.
The landmark JUPITER trial (2008), published in the New England Journal of Medicine, enrolled people with normal LDL cholesterol but elevated hs-CRP and found that statin therapy reduced cardiovascular events in this group — evidence that hs-CRP identifies cardiovascular risk not fully captured by cholesterol levels alone, and that this risk is at least partly modifiable. hs-CRP is incorporated into some cardiovascular risk calculators (such as the Reynolds Risk Score) alongside traditional risk factors.
hs-CRP is nonspecific — it rises with any source of inflammation, including a recent cold, injury, dental work, or obesity, so a single elevated reading should generally be confirmed with a repeat test rather than acted on immediately, and clinicians typically interpret it alongside the full clinical picture rather than as a standalone diagnosis of cardiovascular risk.