Platelet transfusions are traditionally given to patients undergoing
chemotherapy for
leukemia,
multiple myeloma, those with
aplastic anemia,
AIDS, hypersplenism,
idiopathic thrombocytopenic purpura (ITP),
sepsis, bone marrow transplant,
radiation treatment,
organ transplant or surgeries such as
cardiopulmonary bypass. Platelet transfusions should be avoided in those with
thrombotic thrombocytopenic purpura (TTP) because it can worsen neurologic symptoms and
acute renal failure, presumably due to creation of new thrombi as the platelets are consumed. It should also be avoided in patients with
heparin-induced thrombocytopenia (HIT) or
disseminated intravascular coagulation (DIC). In adults, platelets are recommended in those who have levels less than 10,000/μL, or less than 20,000/μL if a
central venous catheter is being placed, or less than 50,000/μL if a
lumbar puncture or major surgery is required.
Whole blood platelets at an
American Red Cross donation center Not all platelet transfusions use platelets collected by automated apheresis. The platelets can also be separated from donations of
whole blood collected in a traditional
blood donation, but there are several advantages to separating the platelets at the time of collection. The first advantage is that the whole-blood platelets, sometimes called "random" platelets, from a single donation are not numerous enough for a dose to give to an adult patient. They must be pooled from several donors to create a single transfusion, and this complicates processing and increases the risk of
diseases that can be spread in transfused blood, such as
human immunodeficiency virus. Collecting the platelets from a single donor also simplifies
human leukocyte antigen (HLA) matching, which improves the chance of a successful transfusion. Since it is time-consuming to find compatible donors for HLA-matched transfusions, collecting a full dose from a single donor is more practical than finding multiple compatible donors. Plateletpheresis products are also easier to test for bacterial contamination, a leading cause of transfusion-associated deaths. Pooling of whole blood platelets is often done in an "open" system where the platelet containers are connected in a way that could expose the platelets to air, and pooled platelets must be transfused promptly so that any contamination does not have time to grow. Problems with apheresis include the expense of the equipment used for collection. Whole blood platelets also do not require any additional donor recruitment, as they can be made from blood donations that are also used for
packed red blood cells and
plasma components.
Thrombocytopenia due to underproduction Recipients in this category include those undergoing chemotherapy, those with
myelophthisic anemia,
AIDS, or with
aplastic anemia. If indicated, transfusions (one thrombapheresis concentrate) should be given until recovery of platelet function, generally approximately twice weekly. Surgical bleeding due solely to thrombocytopenia occurs when platelets < 50,000/μL while spontaneous bleeding occurs when platelets < 10,000/μL. Thrombocytopenic patients can develop "dry" bleeding, that is,
petechiae and
ecchymoses only. They will not suffer fatal hemorrhagic events unless they first have extensive mucosal bleeding, or "wet" bleeding. Therefore, in those with no bleeding or only "dry" bleeding, the threshold for transfusion should be between 5,000 and 10,000/μL. A more conservative threshold of 20,000/μL should be used in those with a fever or other risk factors for bleeding. Those with active bleeding or prior to surgery should have a threshold of 50,000/μL. An unconfirmed, but helpful, way to determine whether a patient is recovering from chemotherapy-induced thrombocytopenia is to measure "reticulated" platelets, or young RNA-containing platelets, which signifies that the patient is starting to make new platelets.
Immune thrombocytopenia Recipients in this category include those with idiopathic thrombocytopenic purpura or drug-induced thrombocytopenia. Platelet transfusions are generally not recommended for this group of patients because the underlying cause involves antibodies that destroy platelets, therefore any newly transfused platelets will also be destroyed. Platelet transfusion may be used in emergency bleeding situations where the platelets could be used by the body before the immune system destroys them.
Altered platelet functions Disorders of platelet function can be congenital or acquired. Most of these disorders are mild and may respond to therapy with
desmopressin (dDAVP). Transfusion is not necessarily required. However, with some more severe disorders such as
Glanzmann thrombasthenia, transfusions with large amount of platelets may be needed. The number of transfusions may be reduced if these patients are given
recombinant human factor VIIa since the underlying cause are antibodies to platelet
glycoproteins IIb/IIIa.
Cardiopulmonary bypass surgery Cardiopulmonary bypass surgery can result in destruction of a large proportion of the patient's platelets and may render the remaining viable platelets dysfunctional. The indications for transfusion in such patients is controversial. General guidelines recommend not transfusing patients prophylactically but only when they are bleeding excessively, while also giving desmopressin.
Drug-induced platelet dysfunction The most common of these is
aspirin, and its similar drug class, the
NSAIDs. Other anti-platelet drugs are commonly prescribed for patients with acute coronary syndromes such as
clopidogrel and
ticlopidine. When surgery is undertaken following the administration of these drugs, bleeding can be serious. Transfusion under these circumstances is not clear-cut and one has to use clinical judgment. == Expected platelet increase after transfusion ==