White blood cells are the body’s natural defense against inflammation and infection. When the white blood cells sense trouble, they release myeloperoxidase (MPO), a protein that can knock the heck out of the bugs causing the inflammation and infection.
But MPO may also irritate arteries and short-circuit natural body chemicals that keep “bad” cholesterol particles from glomming on to artery walls, thus contributing to the buildup of plaque inside your blood vessels. In July 2007, the Journal of the American College of Cardiology published data from a study of more than 1,000 healthy Brits showing that, over the years, those with the highest blood levels of MPO had the highest risk of coronary artery disease (CAD).
In other words, high blood levels of MPO may signal artery trouble ahead, even when other indicators, such as LDL levels, are fine. Naturally, the researchers want to see more studies before they stick an MPO test onto your yearly lab tests, but, as one of the researchers said, “MPO looks like a ‘keeper’ that will one day become part of clinical care.”
Many insurance companies, including Medicare, may not pay for CRP or MPO blood tests because they argue that if you have elevated levels, you need to make all the necessary lifestyle changes (lose weight, treat high blood pressure, stop smoking, eat a healthy diet, and so on). You should be doing this anyway! However, sometimes demonstrating to people that their risk of a heart attack in the next five years is great can stimulate them to become more serious about making lifestyle changes.