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MPO Test (For Risk of Heart Attack & Stroke)

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​Myeloperoxidase (MPO) is a biomarker of oxidative stress that can identify the presence of vulnerable arterial plaques and contribute to determining a person's risk for heart attack.1

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Test at a glance

Clinical Utility

​MPO is frequently used in borderline or high risk patients in conjunction with a lipid panel. It can also be ordered separately. It is not recommended for screening of low risk patients.


​Healthcare provider needs to indicate ‘MPO’ in the ‘Other Tests’ section of the requisition form.

Patient instructions
​Patient needs to bring the completed requisition form to a Patient Service Centre. 

Turnaround Time
​Test results will be available within 2 weeks.

​This test is not currently covered by provincial health plans, but may be covered by the patient’s private insurance.

Healthcare Professional Information

​What is Being Tested?

MPO is an enzyme stored in polymorphonuclear neutrophils and macrophages and released into extracellular fluid during the inflammatory process.  MPO is known to have powerful pro-oxidative and proinflamatory properties.

Oxidative stress participates in all stages of cardiovascular disease, from lipoprotein modification to plaque rupture, and biomarkers of oxidative stress predict development of cardiovascular disease.2 Oxidative stress biomarkers such as MPO may offer long-term cardiovascular risk prediction.3 Utility of MPO and CRP was demonstrated to offer insight into severity of cardiovascular disease following coronary angiography.1

CRP and MPO may be complementary . CRP is a marker of disease activity and vascular inflammation. As such, it is more useful for long-term risk stratification while MPO is a marker of plaque instability and  is more associated with short-term risk.

Patient Frequently Asked Questions(FAQs)

​How is it used?

MPO is used to help determine the risk of heart attack and stroke.

When is it ordered?

MPO is ordered for patients considered to be at borderline risk for heart attack or stroke based on their clinical history. Some of the risk factors for cardiovascular disease include:

  • High blood pressure
  • Diabetes
  • Physical inactivity
  • Borderline or high cholesterol
  • Family history
  • Being overweight
  • Smoking
  • Metabolic syndrome

What does the test result mean?

Atherosclerosis, or hardening of the arteries, occurs due to a prolonged period of arterial inflammation. When the arteries are inflamed, lipids can deposit in the arterial walls and form a so-called 'vulnerable plaque'. Over time this plaque can rupture and be released into the blood stream where it can lead to heart attack or stroke. If elevated, MPO could point to the presence of a vulnerable plaque and a person's elevated risk for heart attack or stroke.1

Is there a charge for the test?

This test is not covered by the provincial health insurance plans, but it may be covered by extended health insurance plans. Contact LifeLabs to find out about the current fee for the test. 

Is there anything else I should know?

50% of heart attacks occur in people with normal cholesterol levels and 68% of heart attacks occur in patients whose arteries are not narrow. This speaks to the need for more effective biomarkers for risk of heart attack.


  1. Heslop et al, 2010. Myeloperoxidase and C-Reactive Protein Have Combined Utility for Long-Term Prediction of Cardiovascular Mortality After Coronary Angiography. Journal of the American College of Cardiology; 55: 1102-1109
  2. Zhang R, Brennan M-L, Fu X, et al. Association between myeloperoxidase levels and risk of coronary artery disease. Journal of the American Medical Association. 2001;286(17):2136–2142.
  3. Meuwese MC, Stroes ESG, Hazen SL, et al. Serum myeloperoxidase levels are associated with the future risk of coronary artery disease in apparently healthy individuals. The EPIC-Norfolk prospective population study. Journal of the American College of Cardiology. 2007;50(2):159–165

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