hs-CRP (High-Sensitivity C-Reactive Protein)
A blood biomarker that measures low-level systemic inflammation. CRP is produced by the liver in response to IL-6. The high-sensitivity assay detects the small elevations relevant to chronic inflammation rather than acute infection. Values below 1 mg/L are considered low risk; 1-3 mg/L is intermediate; above 3 mg/L is associated with significantly elevated cardiovascular and all-cause mortality risk. hs-CRP is one of the most accessible and clinically useful markers of inflammaging -- available on standard panels and generally covered by insurance.