Platelet Counting and Measurement of Platelet Dimensions

Since the introduction of automated blood cell analyzers, platelet counting and platelet dimension measurements are greatly improved in accuracy and disposability. No doubts in considering their relevance evident in routine clinical practice, particularly in diagnosis and management of many bleeding and thrombotic imbalances. Besides the impedance-based one, the first performed, and to date the most diffused, several others automated counting methods have been developed making platelet recognition increasingly more accurate. Platelet counting is now obtained not only by size but also by density and surface glycoproteins’ expression. Although these technological improvements, spurious abnormalities of platelet count such as pseudothrombocytopenia and pseudothrombocytosis can still occur, posing serious diagnostic difficulties. Therefore, in few selected clinical settings, the manual microscopy techniques are still considered of great utility to correctly identify and enumerate platelets. Moreover, the widespread automated cell blood counters make today available additional platelet parameters like the mean platelet volume and the amount of young platelets, calculated as reticulated platelets or immature platelet fraction. Although methodological issues remain to be solved, the availability of these further platelets’ parameters can also drive effectively the diagnosis of common or rare platelet disorders such as immune thrombocytopenia and inherited thrombocytopenias. The relevance in diagnosis and prognosis of these parameters is still under investigations in a large number of platelet diseases and in disorders not primarily affecting platelets.