[Platelet concentrates: types, costs and indications].

Platelet transfusion is a widely used form of therapy and a sound knowledge of its basic principles is essential to obtain the required efficacity while assuring optimal security for the patients. Platelet concentrates (PC) may originate from two types of blood donation: whole blood donation or apheresis. In the first case, the platelets are separated in sterile closed systems following withdrawal of blood from group A or O donors. These so-called "standard" PC (SPC) are most often delivered in the form of mixtures constituting the PC from several donations. In the second case, the platelets are separated from the red blood cells in the course of plasmapheresis or cytapheresis. Generally, these apheresis PC originate from a single donor, except in some cases where the PC from two plasmapheresis donations may be combined. The French Blood Authorities have recently recommended an increase in the proportion of apheresis PC (monodonor) with respect to PC mixtures from several donors, essentially in order to further increase the security against viral contamination. At present, PC are not subjected to viral destruction treatment. In recent times, a number of transfusion centres have introduced systematic determination of the platelet count and volume in all PC delivered, thus enabling inscription on the bag label of the total quantity of platelets (active ingredient) contained in the bag (1 unit = 0.5 x 10(11) platelets). This is useful to calculate the index of platelet recovery after transfusion and to detect refractory states.