At what platelet (plt) count do we transfuse platelets?

From the Guidelines

Platelet transfusions are typically recommended when the platelet count falls below 10 × 10^9/L in stable patients without active bleeding. This recommendation is based on the critical role platelets play in hemostasis, with spontaneous bleeding risk increasing significantly at very low counts 1. For patients undergoing invasive procedures or surgery, a higher threshold of 50,000/μL is generally used, while neurosurgery or ophthalmologic procedures may require counts of at least 100,000/μL due to the high risk of bleeding complications in these sensitive areas.

Some key points to consider when deciding on platelet transfusion thresholds include:

• The risk of spontaneous bleeding increases significantly at platelet counts below 10 × 10^9/L 1
• Patients with active bleeding or those on antiplatelet medications may need transfusions at higher thresholds, typically 20,000-30,000/μL 1
• The AABB recommends transfusing hospitalized adult patients with a platelet count of 10 × 10^9 cells/L or less to reduce the risk for spontaneous bleeding 1
• For patients having elective central venous catheter placement, prophylactic platelet transfusion is suggested for patients with a platelet count less than 20 × 10^9 cells/L 1

When administering platelets, one adult dose (typically one apheresis unit or 4-6 pooled units) usually increases the platelet count by approximately 30,000-50,000/μL in a 70kg adult without platelet consumption issues. Post-transfusion platelet counts should be checked to ensure an adequate response, as some patients may develop refractoriness to platelet transfusions due to alloimmunization or other factors. More recent guidelines also suggest that platelet transfusion should be considered in patients with COVID-19-associated coagulopathy and active bleeding, with a target platelet count of > 50 × 10^9/L 1. However, the most recent and highest quality study on this topic is from 2015, which recommends a threshold of 10 × 10^9/L for stable patients without active bleeding 1.

From the Research

Platelet Transfusion Thresholds

The decision to transfuse platelets is based on various factors, including the patient's platelet count, clinical condition, and the presence of bleeding or risk of bleeding. According to the studies, the following thresholds for platelet transfusion are recommended:

• For hypoproliferative thrombocytopenia in nonbleeding patients receiving chemotherapy or undergoing allogeneic stem cell transplant, platelet transfusion is recommended when platelet count is less than 10 × 10^3/μL 2
• For consumptive thrombocytopenia in neonates without major bleeding, platelet transfusion is recommended when platelet count is less than 25 × 10^3/μL 2
• In patients undergoing lumbar puncture, platelet transfusion is recommended when platelet count is less than 20 × 10^3/μL 2
• In adults with consumptive thrombocytopenia without major bleeding, platelet transfusion is recommended when platelet count is less than 10 × 10^3/μL 2
• For patients with acute myeloid leukemia, a platelet-transfusion threshold of 10,000 per cubic millimeter is considered safe and reduces platelet use by 21.5% compared to a threshold of 20,000 per cubic millimeter 3

Clinical Considerations

The decision to transfuse platelets should be based on individual patient assessment, taking into account factors such as:

• Presence of bleeding or risk of bleeding
• Clinical condition, including temperature, active bleeding, or need for invasive procedures
• Platelet count and trend
• Overall clinical context and alternative therapies
• The use of immature platelet fraction (IPF) measurement may help predict platelet recovery and guide transfusion decisions 4
• Decision time intervals (DTIs) can be used to analyze transfusion practice and identify clinical triggers for platelet transfusion 5

Key Findings

• Restrictive platelet transfusion strategies are recommended, as they reduce the risk of adverse reactions, mitigate platelet shortages, and reduce costs 2
• The use of a lower platelet transfusion threshold (10,000 per cubic millimeter) is safe and effective in reducing platelet use in patients with acute myeloid leukemia 3
• Clinical factors, such as the presence of bleeding or risk of bleeding, should be considered when making decisions about platelet transfusion 2, 5