Plasma proteins are involved in the innate system response to inflammation, tissue injury, or malignancy. During inflammatory processes, the plasma concentration of these proteins, termed acute phase proteins or reactants, increases or decreases by ≥25%. The liver responds by producing acute phase reactants such as C-reactive protein (CRP). CRP and erythrocyte sedimentation rate (ESR) tests are the most commonly used acute-phase markers in clinical practice; of the two, CRP is the preferred (but nonspecific) marker for detecting acute inflammation.
Other acute phase proteins are used to diagnose other conditions (eg, assessing iron stores with ferritin) but are not regularly used clinically as markers of inflammation.
Last Update: March 2018