Myeloperoxidase (MPO) is an enzyme released by leukocytes and some macrophages. Elevated levels suggest a possible ongoing inflammatory process. MPO is also involved in the degradation of the plaque matrix in atherosclerosis. Increased serum concentrations of MPO may indicate both an inflammatory process and plaque instability. Immunoassays for MPO are available and are sometimes used to assess cardiovascular risk. However this marker is rarely used and not well known to most clinicians. Its future as a novel cardiovascular risk marker remains to be proven.
It is worth noting that antibodies to MPO are also measured. This testing has little to do with cardiovascular disease but rather is done in the setting of autoimmune disease. Patients with MPO antibodies may present with azotemia (high BUN and creatinine) secondary to glomerulonephritis.
