The big picture: C-Reactive Protein (CRP) is produced by the liver in response to inflammation or infection. The high-sensitivity CRP (hs-CRP) test is designed to detect low, yet persistent, levels of inflammation. High hs-CRP levels are associated with various chronic conditions, in particular cardiovascular disease,

Function and measurement: CRP plays a crucial role in the immune system by binding to damaged cells or microbes, facilitating their removal by white blood cells. This process is essential for defending against infections. The hs-CRP test specifically measures CRP levels within the 0 to 10 mg/L range to identify low-grade inflammation. Conversely, the standard CRP test, detecting levels from 10 to 1,000 mg/dL, focuses on identifying serious infections or inflammatory conditions.

Acute vs chronic inflammation: CRP levels spike significantly in response to acute infections or injuries, aiding in restoring physiological balance. These elevations are typically temporary, with CRP levels normalizing within 18-20 hours post-disturbance. Such inflammatory responses, including those following exercise, can be beneficial. However, continuous, elevated CRP levels suggest chronic inflammation, a condition that may lead to tissue and organ damage and increase the risk of autoimmune diseases due to the immune system's overactivity.

Predictor of cardiovascular risk: Individuals with hs-CRP at the higher end of the normal range face a quadrupled risk of myocardial infarction compared to those at the lower end. hs-CRP values ranging from 3.1 to 10 mg/L double the likelihood of cardiovascular diseases, a risk further elevated in individuals with type 2 diabetes.

Synergistic risk with Lp-PLA2: High levels of hs-CRP, alongside Lp-PLA2 (another inflammatory marker specific to blood vessels), significantly increase the risk of heart disease and stroke, even in cases of low or moderate LDL cholesterol levels. Notably, in the ARIC Study, when both Lp-PLA2 and hs-CRP were in the top tertile, the risks for coronary heart disease events and stroke increased 4-fold and 11-fold, respectively, compared with those in the lowest tertile for both markers.