Platelet transfusions are indicated for the prevention and treatment of hemorrhage in patients with thrombocytopenia or platelet function defects. Their main use is in the prevention of bleeding in patients with hematologic malignancies who have marrow failure caused by their disease or treatment.
     For such patients it has become accepted clinical practice to tranfuse platelets when platelet levels are very low. Ever since in the early 1960's a clear relationship between hemorrhage and platelet count was documented in patients with acute leukemia, the threshold for platelet transfusions has been debated (1).
     These early studies suggested a threshold of 20,000 / mm³, and an NHI consensus conference published in 1987 supported this level for most patients, although it was also concluded that lower levels were safe for patients in stable condition (2,3).
     More recent studies, however, have shown that a threshold platelet level of 10,000 / mm³ in stable patients is equally safe. This lower threshold level will result in nearly 25% fewer platelet transfusions than the 20,000 / mm³ level. Consequently, this lower threshold will also result in lower cost, and less exposure to donor blood products (4).

Perhaps thresholds below 10,000 / mm³ are safe for stable patients, but the poor reproducibility of automated platelet counts below 10,000 / mm³ makes the study of this topic difficult (5).
     For patients with fever, active bleeding or invasive procedures, platelet thresholds higher than 10,000 / mm³ may well be indicated.
     IBMT policies stipulate the transfusion of platelets for the following indications in patients with bone-marrow failure:

• stable patients with platelet counts less than 10,000 / mm³
• patients with platelet counts less than 20,000 / mm³ and signs of hemorrhagic diathesis
• patients with platelet counts less than 50,000 / mm³ and massive bleeding
• patients with platelet counts less than 50,000 / mm³ who have to undergo major surgery