Platelets

Platelets are essential for the initial phase of hemostasis. Platelets are prepared by using a centrifuge to separate the platelet-rich plasma from the donated unit of whole blood. These random donor platelet concentrates contain about 60mL of plasma and small numbers of red blood cells and leukocytes. If ABO compatible platelets are unavailable, ABO incompatible platelets can be substituted with very little risk.

Platelets may also be obtained from a single donor by a process known as apheresis, or plateletpheresis. In this process, blood is drawn from the donor into an apheresis instrument which separates the blood into its components, retains some of the platelets, and returns the remainder of the blood to the donor. Apheresis platelets are equivalent to approximately 5-6 pooled units and have a small number of red blood cells and leukocytes.

Platelets are used to treat thrombocytopenia and/or platelet function abnormalities. Platelets should not be used to treat thrombocytopenia due to platelet destruction such as ITP, TTP, HUS, HELLP syndrome, etc.

Dosage

The volume of a dose of platelets is approximately 350-400mL. The initial recommended dose for an adult is 6 units of pooled random donor platelets or one apheresis unit; for pediatrics, the dose is 5-10mL/kg. This dose will usually increase the platelet count by approximately 25K-35K/microliter.