Platelets are a type of blood cells that are responsible for clotting of blood. The newer hematology analysers generate a large number of parameters for each cell type. Besides quantitating platelets, they also measure platelet indices like mean platelet volume (MPV), platelet distribution (or size deviation) width (PDW) and platelet-to-large-cell ratio (P-LCR). Mean platelet volume (MPV) is an instrument-generated measurement of the average size of platelets. Freshly formed or younger platelets are larger in size and MPV is increased when an increased numbers of platelets are being produced and provides information about platelet production in the bone marrow, being is inversely correlated with the platelet count. The platelet size is a marker of platelet function and larger-sized platelets are functionally more reactive.
An increased MPV is seen in conditions where there is platelet destruction while it is decreased in conditions in which there is impaired platelet production in the bone marrow. The MPV also increases as the platelets swell up when blood is collected in EDTA anticoagulant and left for more than 2-hours. A higher-than-normal MPV has been associated with an increased risk of heart attacks and stroke in some studies. It is difficult to ascribe risk to a specific MPV value but an MPV of approximately 12.0fL or greater may be considered a risk factor for these vascular complications. Increased MPV values have also been reported in patients with vascular risk factors such as diabetes mellitus, hypercholesterolemia, and smoking. But the routine clinical use of this parameter still awaits further definition of diagnostic utility.