Myeloperoxidase
Also known as: MPO
What Does Myeloperoxidase Measure?
Myeloperoxidase (MPO) is an enzyme primarily found in neutrophils, a type of white blood cell that serves as one of the body's first responders to infection and inflammation. When measured in a blood test, MPO levels reflect the activity and degranulation of these neutrophils, providing a window into how intensely the immune system is responding to perceived threats. The test typically measures MPO concentration in the blood plasma or serum in units such as pmol/L or ng/mL.
Why Does Myeloperoxidase Matter?
MPO is a powerful marker of systemic inflammation and oxidative stress, and has emerged as a particularly important biomarker for cardiovascular disease risk. Elevated MPO levels indicate that neutrophils are releasing highly reactive oxidizing compounds that can damage blood vessel walls, oxidize LDL cholesterol (making it more dangerous), and destabilize arterial plaques — all of which increase the risk of heart attack and stroke. Beyond cardiovascular risk, MPO is also monitored in conditions such as inflammatory bowel disease, kidney disease, neurological disorders, and certain cancers, making it a versatile marker for tracking inflammatory burden across multiple body systems.
Normal Ranges
Males
< 469 pmol/L (approximately < 17.5 ng/mL); some labs use < 500 pmol/L
Females
< 469 pmol/L (approximately < 17.5 ng/mL); reference ranges are generally the same as males in most assays
Children
Varies by age; generally lower than adult values; pediatric-specific reference ranges should be used
Causes of High Levels
- Acute or chronic cardiovascular disease, including atherosclerosis and coronary artery disease
- Active bacterial or viral infections triggering intense neutrophil activation
- Chronic inflammatory conditions such as rheumatoid arthritis, lupus, or inflammatory bowel disease
- Obesity and metabolic syndrome, which promote low-grade systemic inflammation
- Smoking and exposure to environmental pollutants, which activate neutrophils
- Chronic kidney disease, where impaired clearance and uremic toxins drive neutrophil activation
Causes of Low Levels
- Myeloperoxidase deficiency, a rare inherited genetic condition where the enzyme is absent or non-functional
- Immunosuppressive therapy (e.g., corticosteroids, chemotherapy) that reduces neutrophil activity
How to Improve Your Myeloperoxidase
Diet
- Adopt a Mediterranean-style diet rich in vegetables, fruits, whole grains, legumes, and olive oil to reduce systemic inflammation
- Increase intake of omega-3 fatty acids from fatty fish (salmon, mackerel, sardines) 2-3 times per week to dampen neutrophil-driven inflammation
- Eat cruciferous vegetables (broccoli, Brussels sprouts, kale) regularly, as sulforaphane compounds help reduce oxidative stress
- Reduce consumption of ultra-processed foods, refined sugars, and trans fats, which promote neutrophil activation
- Incorporate polyphenol-rich foods such as berries, dark chocolate, green tea, and turmeric to combat oxidative damage
Supplements
- Omega-3 fish oil: 2–4 grams of EPA+DHA daily has been shown to reduce MPO and inflammatory markers
- Vitamin C: 500–1000 mg daily as an antioxidant that can help neutralize MPO-generated oxidants
- N-acetylcysteine (NAC): 600–1200 mg daily to boost glutathione levels and reduce oxidative stress
- Curcumin (from turmeric): 500–1000 mg daily with piperine for enhanced absorption to reduce neutrophil-driven inflammation
- Vitamin E (mixed tocopherols): 200–400 IU daily as a lipid-soluble antioxidant that protects against MPO-mediated LDL oxidation
Related Biomarkers
Frequently Asked Questions
What does a high MPO level mean for my heart health?
Elevated MPO is a strong independent predictor of cardiovascular events, including heart attack and stroke. MPO released by activated neutrophils oxidizes LDL cholesterol, making it more likely to accumulate in artery walls. It also degrades nitric oxide — a molecule essential for keeping blood vessels relaxed and healthy — and can destabilize existing arterial plaques, making them more prone to rupture. Research shows that people with elevated MPO have up to a 2–3 times higher risk of major cardiovascular events compared to those with normal levels, even when other traditional risk factors are controlled for.
Can MPO levels be improved naturally without medication?
Yes, lifestyle and dietary changes can meaningfully reduce MPO levels. The most impactful strategies include quitting smoking (one of the fastest ways to reduce MPO), adopting an anti-inflammatory diet rich in omega-3 fatty acids and antioxidants, engaging in regular moderate exercise, achieving or maintaining a healthy weight, and improving sleep quality. Studies have shown that Mediterranean dietary patterns, omega-3 supplementation, and regular aerobic exercise can each independently lower MPO and related inflammatory markers within weeks to months.
How is the MPO test performed, and do I need to fast?
The MPO test is a simple blood draw, typically from a vein in your arm. It can be measured in serum or plasma. In most cases, fasting is not strictly required for MPO testing alone, but your doctor may recommend fasting if MPO is being measured alongside a lipid panel or other metabolic markers. Results are usually available within a few days. Some specialized cardiovascular risk panels, such as the Cleveland HeartLab panel, include MPO as a component alongside other inflammation and oxidative stress markers.