CRP is a pentameric protein synthesized by the liver, whose level rises in response to inflammation. CRP is an acute-phase reactant protein that is primarily induced by the IL-6 action during the acute phase of an inflammatory/infectious process. CRP has both proinflammatory and anti-inflammatory properties. It plays a role in the recognition and clearance of foreign pathogens and damaged cells by binding to phosphocholine, phospholipids, histone, chromatin, and fibronectin. It can activate the classic complement pathway and also activate phagocytic cells.

Uric acid constitutes the final product of the metabolism of purine bases originating from the catabolism of nucleic acids, but also from endogenous synthesis or from food. At physiological pH, uric acid is almost completely ionized and is present in plasma as sodium urate. Uric acid and urate are relatively insoluble molecules that readily precipitate in aqueous solutions such as urine or synovial fluid, potentially causing stone disease or arthritis.