MPV is an indicator of the size of the platelets, whose function is to clot blood. Platelets with a higher volume are more active. The total platelet mass (combination of platelet count and size) is controlled, and the mean platelet volume tends to be higher when the platelet count is lower. MPV results are interpreted in light of not only the platelet count, but also other clinical data and the blood count.
In a patient with thrombocytopenia (below normal platelet count), a high MPV suggests that the bone marrow is compensating by producing new platelets. Although a bone marrow disorder cannot be ruled out (congenital abnormalities, myelodysplastic syndromes), causes not involving the bone marrow are common (inflammatory or autoimmune diseases that destroy platelets). However, thrombocytopenia associated with a low MPV is more consistent with the suppression of cell production by the bone marrow (aplastic anemia or congenital abnormality).
A high MPV seems to be associated with a cardiovascular risk and an increased risk of thrombosis (phlebitis, etc.). In a person who has no history of bleeding and a normal platelet count, an abnormal PMV is of less clinical usefulness.