Platelets

Platelets are a blood component used to treat low blood platelet counts (thrombocytopenia) or platelet dysfunction, to treat active platelet-related bleeding, or as prophylaxis in those at serious risk of bleeding.

• Typical indications include leukemia, myelodysplasia, aplastic anemia, solid tumors, congenital or acquired/medication-induced platelet dysfunction, central nervous system trauma, and patients undergoing extracorporeal membrane oxygenation or cardiopulmonary bypass may also need platelet transfusion.

Dosage Forms and Strengths

• Typical dosing for an adult is a pool of 6 whole blood-derived (sometimes referred to as random donor) platelets or one apheresis platelet.

Thrombocytopenia

Typical dosing for an adult is a pool of 6 whole blood-derived (sometimes referred to as random donor) platelets or one apheresis platelet. This is expected to raise the platelet count by 30,000-60,000/uL in a 70 kg patient. Transfused platelets have a short life span and will need to be re-dosed within 3-4 days if given for prophylaxis. Suboptimal increases can be seen due to non-immune destruction or immune refractoriness. If suboptimal increases are suspected, the corrected count increment (CCI) can help determine if the response is truly suboptimal based on the number of platelets transfused compared to body surface area. The CCI can also assist in determining whether the response is due to immune refractoriness or non-immune causes. Please see the pharmacology section for CCI calculations.

Neonates and small children

• Transfusion of 5-10 mL/kg should raise the platelet count by 50,000-100,000/uL

Children greater than 10 kg

• Transfusion of 1 unit of whole blood-derived platelets per 10kg should raise the platelet count by 50,000/uL
• Transfused platelets have a short life span and will need to be re-dosed within 3-4 days if given for prophylaxis. Suboptimal increases can be seen due to non-immune destruction or immune refractoriness. If suboptimal increases are suspected, the corrected count increment (CCI) can help determine if the response is truly suboptimal based on the number of platelets transfused compared to body surface area. The CCI can also assist in determining whether the response is due to immune refractoriness or non-immune causes.

Other Indications and Uses

• Platelet transfusions may be given for thrombocytopenia or platelet dysfunction to treat active platelet-related bleeding or as prophylaxis in those at serious risk of bleeding.
• Typical indications include leukemia, myelodysplasia, aplastic anemia, solid tumors, congenital or acquired/medication-induced platelet dysfunction, central nervous system trauma, and patients undergoing extracorporeal membrane oxygenation or cardiopulmonary bypass may also need a platelet transfusion.
• Thresholds for transfusion due to thrombocytopenia have been controversial. However, it is generally accepted that a count of 50,000/uL is sufficient for most invasive procedures including most surgeries. Platelet counts of greater than 100,000/uL are recommended for ophthalmic and neurosurgery. Higher transfusion thresholds may be appropriate for patients with platelet dysfunction.
• Probably the most controversial threshold is for the clinically stable patient with an intact vascular system and normal platelet function. Prophylactic platelet transfusions may be appropriate at 5,000- 10,000/uL to prevent spontaneous bleeding. Patients with autoimmune destruction of platelets, such as idiopathic thrombocytopenic purpura (ITP), may not receive therapeutic benefit from prophylactic transfusion, but may however benefit from transfusion if bleeding.

Common side effects of platelets include:

• Hemolytic transfusion reactions
• Febrile non-hemolytic reactions
• Allergic reactions ranging from hives to severe (anaphylaxis)
• Septic reactions
• Transfusion Related Acute Lung Injury (TRALI)
• Circulatory overload
• Transfusion associated graft versus host disease
• Post-transfusion purpura

This is not a complete list of side effects and other serious side effects may occur. Call your doctor for information and medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

If your doctor has directed you to use this medication, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

• Platelets have no known severe, serious, moderate, or mild interactions with other drugs.

This document does not contain all possible interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share the list with your doctor and pharmacist. Check with your physician if you have health questions or concerns.

Warnings

This medication contains platelets. Do not take platelets if you are allergic to platelets or any ingredients contained in this drug.

Keep out of reach of children. In case of overdose, get medical help or contact a Poison Control Center immediately.

Contraindications

• Platelet transfusions are contraindicated in patients with thrombotic thrombocytopenic purpura (TTP), hemolytic uremic syndrome (HUS), or heparin-induced thrombocytopenia (HIT). Although these conditions can have marked thrombocytopenia, they are generally pro-thrombotic and transfusion of platelets may “fuel the fire” if transfused as prophylaxis in the absence of significant bleeding.
• Platelet transfusions are controversial in patients with Post Transfusion Purpura since platelet-specific antibodies against high-frequency platelet antigens are part of the pathophysiology of this potentially fatal disorder. IVIG is typically the first-line therapy and immediate consultation with a hematologist and/or your institution's transfusion medicine physician is highly recommended.
• Platelet transfusions in patients with autoimmune destruction of platelets such as idiopathic thrombocytopenic purpura (ITP) should not be transfused in the absence of bleeding because the transfused platelets will be quickly removed similarly to the patient's own platelets without clinical benefit.

Effects of Drug Abuse

• None

Short-Term Effects

• See "What Are Side Effects Associated with Using Platelets?"

Long-Term Effects

• See "What Are Side Effects Associated with Using Platelets?"

Cautions

• If a transfusion reaction is suspected, the transfusion should be stopped, the patient assessed and stabilized, the blood bank notified, and a transfusion reaction investigation initiated. Massive or rapid transfusion may lead to arrhythmias, hypothermia, hyperkalemia, hypocalcemia, dyspnea, and/or heart failure.
• Platelet products have an increased risk of significant bacterial contamination/sepsis compared to other blood products because platelets must be stored at room temperature since they rapidly lose function when refrigerated. The risk of sepsis with platelet transfusion is thought to be at least 1:75,000 and the risk of fatal septic platelet transfusion reactions is thought to be at least 1:500,000. Bacterial contamination is more commonly caused by Gram-positive skin flora such as Staphylococcus spp but septic reactions can be due to either Gram-positive or Gram-negative organism contamination. Gram-negative organisms are usually associated with more severe reactions, but broad-spectrum antibiotics should be initiated until the causative organism is identified.
• Due to the short shelf life of platelets (5 days from collection), it is not uncommon for blood banks to experience platelet shortages, which can delay transfusion for those who have urgent need of a transfusion.
• If ABO identical platelets are not available, platelets from donors who are ABO plasma compatible may be used. This may occasionally result in suboptimal responses since platelets have a variable amount of ABO antigens, but will not cause clinically significant problems. In large children and adults, ABO-incompatible platelets may be issued with only minimal risk of hemolysis, unless large doses of ABO-incompatible platelets are transfused. If platelets that are ABO identical or from ABO plasma compatible donors are not available, then efforts to volume reduce or wash the platelets may be considered for neonates if the platelets are not needed urgently. Washing and volume reduction will require significant delays in transfusion and may alter the quantity and quality of the platelet product.
• Because all platelet products contain a small number of RBCs, Rh-compatible platelets should be used if possible to prevent the formation of anti-D in Rh-negative individuals. This is particularly important for females that are pregnant or may become pregnant in the future because of the risk of hemolytic disease of the fetus and newborn due to anti-D. The risk of anti-D formation, particularly in this population, can be minimized by providing RhIG within 72 hours of exposure. RhIG is often offered in both intramuscular (IM) and intravenous (IV) suspensions. Use of IV RhIG may be considered if the amount of RhIG needed is large or the patient is at increased risk of injury from IM injections but is not available in all institutions. One full standard dose of RhIG will be sufficient to cover at least 5 adult doses of pooled whole blood-derived platelets or 7 doses of apheresis platelets. Repeat dosing depends on the number of Rh-positive platelet doses received and the half-life of RhIG and may need to be considered if it has been greater than 21 days since the last dose of RhIG and additional Rh-positive platelets are to be transfused.
• Platelet transfusions may induce the formation of HLA antibodies and rarely platelet-specific antibodies that may cause immune refractoriness for future transfusions, particularly for patients that require numerous platelet transfusions. The CCI may help determine if the patient has immune refractoriness and its calculation is described in the pharmacology section. Leukocyte reduction may help decrease HLA sensitization. Please see the leukocyte reduced blood products monograph for more complete indications of leukocyte reduced products. Patients with HLA or platelet-specific antibodies (HPA-1a) may benefit from HLA matched or HPA-1a negative apheresis platelet transfusions if available. Please see their respective monographs for complete transfusion information.
• Patients at increased risk of TA-GVHD should receive irradiated platelet products. For more information regarding indications for irradiation to prevent TA-GVHD, please see the irradiated blood products monograph. Patients that are CMV seronegative or whose CMV status is unknown and are at increased risk of symptomatic CMV infection should receive CMV reduced risk platelets.
• All transfusions must be given via blood administration sets containing 170- to 260-micron filters or 20- to 40-micron micro aggregate filters unless transfusion is given via a bedside leukocyte reduction filter. No other medications or fluids other than normal saline should be simultaneously given through the same line without prior consultation with the medical director of the blood bank.
• Patients should be monitored for signs of a transfusion reaction including vitals pre, during, and post-transfusion.
• Non-septic infectious risks include transmission of HIV (~1:2 mill), hepatitis C virus (~1:1.5 mill), hepatitis B virus (1:300k), human T-cell leukemia-lymphoma virus (HTLV), West Nile virus, cytomegalovirus (CMV), parvovirus B19, Lyme disease, babesiosis, malaria, Chagas disease, or Creutzfeldt–Jakob disease.
• Consult with the blood bank medical director or hematologist if you have questions regarding special transfusion requirements.

Pregnancy and Lactation

• Cytomegalovirus (CMV)-seronegative or CMV reduced risk (leukocyte reduced) platelets should be used in pregnant women who are CMV-seronegative or whose CMV status is unknown.
• IgG antiplatelet antibodies are transmitted through breast milk, so consider monitoring the platelet counts in breastfed newborns of mothers with idiopathic thrombocytopenic purpura (ITP).