MPV is a count of how large your platelets actually are. The purpose of measuring the size of the platelets is also to determine whether or not there is an issue with the platelet production in the bone marrow.
By measuring your MPV along with your platelet counts, your doctor will better be able to tell you exactly what's wrong with you if there is anything wrong at all. MPV IS NOT DIAGNOSTIC OF ANYTHING ALONE. so the mpv of 6.4 is a little bit low but without a medical and physical history and the rest of the blood test it doesn't mean much.