Myeloperoxidase (MPO)
Measures myeloperoxidase enzyme levels to assess cardiovascular inflammation and heart disease risk.
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Lab testing services linked from this site are not available to residents of Alaska, Arizona, or Hawaii, unless otherwise noted on the lab's own website.
This publication is not intended to solicit the purchase of laboratory testing from any individual consumer.
What this test measures
Myeloperoxidase (MPO) is an enzyme released by neutrophils and monocytes, two types of white blood cells that serve as front-line immune defenders. Its primary role in immune defense is generating highly reactive oxidizing compounds, including hypochlorous acid, to destroy bacteria and other pathogens.
In the cardiovascular system, however, MPO takes on a damaging role. When white blood cells are activated by injured or inflamed artery walls, they release MPO into the surrounding tissue, where it oxidizes LDL cholesterol into a particularly harmful form that accelerates plaque formation. This dual nature makes MPO both a marker of vascular inflammation and an active participant in plaque development. Research has linked MPO to multiple stages of atherosclerosis, from the initial endothelial injury through plaque progression to the acute rupture events that precipitate heart attacks. Elevated MPO levels may therefore signal active vascular inflammation and an increased near-term risk of cardiovascular events.
Who should consider this test
You might consider this test if you are experiencing any of the following:
- Individuals with multiple cardiovascular risk factors who want to assess their level of arterial inflammation beyond standard cholesterol testing.
- Those with a family history of heart disease or cardiovascular events despite having normal cholesterol levels who need additional risk stratification.
- Patients with metabolic syndrome, diabetes, or insulin resistance who may have elevated inflammatory markers contributing to cardiovascular risk.
- People who are current or former smokers, as MPO levels can help quantify residual neutrophil activation and ongoing vascular oxidative stress.
- Individuals being monitored for response to anti-inflammatory cardiovascular interventions such as statin therapy or omega-3 supplementation.
What to expect
Preparation
No special preparation is required for the MPO test. No fasting is necessary, and patients may continue taking their regular medications. However, the test should be performed during stable health conditions.
Sample Type
A healthcare professional will collect a blood sample from a vein in the arm using standard venipuncture techniques. The blood is collected in a special tube containing EDTA anticoagulant to preserve the sample.
Collection
The blood draw is quick and typically takes just a few minutes. After collection, the sample must be processed promptly, with plasma separated from blood cells within two hours to ensure accurate results.
Turnaround
Test results are typically available within 1-3 business days after the laboratory receives the sample.
Understanding your results
Results are typically reported in picomoles per liter (pmol/L), with levels below approximately 400 to 470 pmol/L considered within the normal range. Because MPO is an immune-system enzyme, levels can rise temporarily during acute infections, surgical recovery, or any active inflammatory condition unrelated to cardiovascular disease. For this reason, results are most reliable when drawn during a period of stable health. Healthcare providers interpret MPO alongside other cardiovascular markers, clinical symptoms, and overall inflammatory status to assess whether vascular inflammation may be contributing to cardiovascular risk.
| Population | Reference Range | Notes |
|---|---|---|
| Adults | Less than 400 pmol/L | Normal range indicating low cardiovascular inflammation risk |
| Adults | 400-480 pmol/L | Moderately elevated levels suggesting increased cardiovascular risk |
| Adults | Greater than 480 pmol/L | Significantly elevated levels indicating high cardiovascular inflammation risk |
Reference ranges may vary by laboratory and individual factors. Results should be interpreted by a healthcare provider in the context of your overall health.
What does a “Low” result mean?
Lower-than-normal MPO levels may indicate a deficiency of white blood cells or reduced immune system activity. In the cardiovascular context, lower MPO levels generally suggest reduced vascular inflammation and oxidative stress. However, very low levels should be evaluated in the context of overall immune function and white blood cell counts to ensure adequate immune system function.
What does a “High” result mean?
Elevated MPO levels may indicate the presence of inflammation, infection, or disease processes such as bacterial infections, autoimmune diseases, cancer, or inflammatory conditions. In the cardiovascular context, higher MPO levels are associated with increased risk of heart disease and may predict cardiovascular events independent of traditional risk factors like LDL cholesterol. Two individuals with identical cholesterol levels can have dramatically different cardiovascular risk based on their MPO levels.
Privacy & confidentiality
Your MPO test results are completely confidential and protected under HIPAA regulations. Results are not automatically shared with your personal physician or added to your medical records unless you specifically request it. No insurance billing or explanation of benefits is generated for this direct-pay testing service.
Frequently asked questions
Related tests
C-Reactive Protein (CRP)
Another inflammatory marker that complements MPO for comprehensive cardiovascular inflammation assessment
View TestLipid Panel
Standard cholesterol testing that provides baseline cardiovascular risk assessment alongside MPO inflammation markers
View TestHomocysteine
Additional cardiovascular risk marker that measures a different aspect of heart disease risk when combined with MPO
View TestHeart Health Panel
Comprehensive cardiovascular assessment that may include multiple heart disease risk markers
View TestRelated conditions
Last reviewed: April 2026
CPT Code: 83876
This test may not be available in: NY, NJ, RI
This page is for informational purposes only and does not constitute medical advice. Always consult with a healthcare provider regarding any health concerns. LevelPanel does not diagnose, treat, or prescribe.
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LevelPanel has no business or affiliate relationship with Quest or LabCorp. These links are provided as a public service.
Lab testing services linked from this site are not available to residents of Alaska, Arizona, or Hawaii, unless otherwise noted on the lab's own website.
This publication is not intended to solicit the purchase of laboratory testing from any individual consumer.
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