What is hs-CRP?

C-reactive protein is part of the liver's rapid defensive reaction to signals sent by immune cells and damaged tissue. That reaction is the same wherever the trouble is: an infection, a tissue injury and an inflamed joint all produce it, so hs-CRP says inflammation is happening and not where.

WBC Count and Neutrophil Count show how many immune cells are in circulation; hs-CRP shows how strongly the liver has answered them.

An infection or a tissue injury raises hs-CRP sharply. Steadier influences run underneath that: obesity, smoking and persistent joint or metabolic inflammation all keep a mild signal going. Age and sex shift the usual amount in the blood even when there is no infection or injury.

hs-CRP climbs within six to eight hours of an infection, peaks around two days later, then falls away over one to two weeks. One measurement cannot tell a passing cold from a signal that never switches off. Readings about every four months can: a two-week episode rarely lands in more than one of them, and a persistent signal lands in all. This is Do Health's monitoring schedule, not a general recommendation for everyone.