hs-CRPHigh-sensitivity C-reactive protein

C-reactive protein (CRP) is made by the liver and rises when there is inflammation in the body. The high-sensitivity assay (hs-CRP) can detect the low, chronic levels that ordinary CRP tests miss, rather than only the large spikes of an acute infection.

It matters because chronic low-grade inflammation is linked to cardiovascular and metabolic risk and to biological ageing, so hs-CRP is used as one input into heart-risk and biological-age assessments. It is non-specific, though — any recent infection, injury or hard training session can raise it temporarily.

In practice, hs-CRP is best measured when you are well and not freshly trained, and is read as part of a wider picture rather than on its own.