This is the formal name for a unit of whole blood derived platelets (known to some as “platelet concentrate” or “random platelets”) that has had the vast majority of its white blood cells removed (see the entry on leukocyte reduction for more information on why we would do so). By definition, quality testing of this product must show that more than 75% of the units have a platelet count of 5.5 x 10¹⁰ or more (this differs from the proportion required to have that count in non-leukoreduced platelets: 90%), and 95% of units tested must have a residual white blood cell count of less than 8.3 x 10⁵. In addition, over 90% must have a pH of >6.2 at the end of storage.

Don’t get confused; this product is different from the leukocyte-reduced version of apheresis-derived platelets, a much more commonly used product.