It means the platelets are bigger than normal. They don't fragment properly. But the good news is that you've got plenty of platelets. My MPV hangs out between 13-15.5. Has been this way for years. Might want to get B12 looked at. Really improved my counts. Went from 50-80k now low normal 130-155.
Best wishes
This is a great breakdown.
http://www.metromedlab.com/SiteConte...0%20101609.pdf