What is MPO?
MPO is short for myeloperoxidase. MPO is an enzyme. Enzymes are special types of protein found in the body that cause chemical changes. MPO is usually stored in a certain type of white blood cell. These cells release MPO when blood vessels are injured or become inflamed.
How is MPO related to heart attack?
Your MPO level is a way to assess your risk of heart attack. Research shows that when arteries get inflamed on the inside, it can lead to a heart attack. As cholesterol and fat (plaque) collect and build up in the artery walls, the artery wall becomes inflamed. Eventually, the inflammation gets bad enough that the plaque bursts through the artery wall and into the blood, causing a clot to form. When a clot completely blocks blood flow to the heart, it causes a heart attack.
MPO plays a role in the inflammation in the artery wall. It also gets released when inflammation occurs. MPO in the blood can also accumulate in the artery wall, so MPO that is released from other areas of the body that are inflamed (like an inflamed joint or even gum disease) can collect inside the arteries. Multiple studies show that the plaque in the artery walls contains large amounts of MPO. This is especially true in places that are prone to rupture and can lead to heart attacks. White blood cells in the blood also seem to release more MPO into the bloodstream when the artery wall becomes inflamed, causing a "vicious cycle." Studies show that the inflammation and release of MPO can happen years before a heart attack occurs.
Once MPO is released, it increases the risk of heart attack in several ways:
- MPO changes low-density lipoprotein (LDL/"bad") cholesterol into an even more harmful form that easily collects as plaque in the arteries.
- MPO produces a substance that directly damages the artery wall. This makes the plaque unstable and more likely to rupture.
- MPO interferes with the protective effects of high-density lipoprotein (HDL/"good") cholesterol. It also keeps the body from getting enough nitric oxide, a substance in the body that expands blood vessels.
Why should I have my MPO level tested?
Measuring the level of MPO in your body can help your doctor identify inflammation in your arteries. If you have inflammation, it means you are at a higher risk of having a heart attack.
The test lets people with an otherwise low risk of heart attack find out if they have a higher risk than they know. Patients with known coronary artery disease, chest pain or other risk factors can also benefit from getting their MPO level checked. Studies show that, among patients with chest pain, an increased MPO level can predict their risk of heart attack over the next 30 days to six months. In other, longer studies involving middle-aged patients who were assumed to be healthy, an elevated MPO level predicted the risk of heart attack over 2 to 10 years.
When is the MPO test performed?
If your doctor recommends that you have an MPO test, it will likely be done at the same time as other blood tests, such as a cholesterol test.
How should I prepare for the MPO test?
Your MPO level will be checked with a simple blood test. You do not need to follow any special instructions for the test. It can be done at any time of the day. You do not need to fast or stop taking any medications. But, if you are having blood drawn for other tests, you may need to follow special instructions not related to the MPO test.
What do the test results mean?
- Goal: <400 pmol/L
- Low risk: 400 - 480 pmol/L
- High risk: ≥480 pmol/L
What should I do if my MPO level is high?
If your MPO level is high, you may need more tests. You should talk to your doctor about what you can do to lower your MPO level and reduce your overall cardiovascular risk. To help reduce your risk, your doctor may recommend that you:
- Eat a heart-healthy diet. This means eating foods that are low in fat and eating lots of fruits, vegetables and whole grains.
- Reach and maintain a healthy.
- Keep your blood pressure under control. If you have high blood pressure, follow your doctor’s recommendations for medications, exercise and diet.
- Quit smoking, if you smoke.
- Increase your level of physical activity.
- Work with your doctor to do more to prevent cardiovascular problems. This can include lowering your LDL cholesterol level, paying closer attention to your blood pressure, managing your weight, and exercising more.
Is the MPO test covered by insurance?
Most commercial insurance companies and Medicare cover the cost of the MPO test. If you have a question about your coverage, please contact your insurance provider.
Where can I get more information about MPO and MPO testing?
To learn more about MPO and MPO testing, contact a Sydell and Arnold Miller Family Heart & Vascular Institute Resource & Information Nurse. You can call a nurse at: 216.445.9288, toll-free 800.289.6911.
