Platelet Dosage
The dose of platelets should be individualized. A number of simple guidelines can be used to calculate the appropriate dose.
- A dose of 1 random donor platelet concentrate per 10 kg body weight can be expected to increase the platelet count by 5000/uL in a non-refractory patient.
- One random donor platelet concentrate is expected to increase the platelet count by 5000 to 10, 000/uL in a 70 kg patient who is not refractory.
- Generally, a pool of 6 to 8 platelet concentrates or a single apheresis unit is sufficient to correct or prevent bleeding in a normal sized adult weighing up to 90 kg.
- One apheresis product is equivalent to 6 to 8 random donor platelet concentrates and therefore should increase the platelet count by 30,000/uL to 40,000/uL in a 70 kg patient.
- For pediatric patients, 5 mL/kg body weight of a random donor platelet concentrate should increase the platelet count by 5000/uL. A single platelet concentrate contains about 45 to 50 mL and should supply the needs of patients up to 8 kg. If the entire platelet concentrate is not used for a given patient, it is not practical to salvage the remainder of the unit.
- For children >8 kg, a standard dose of 1 unit/10 kg should be used.
- In the absence of increased platelet destruction, platelet transfusion will usually need to be repeated every 3-5 days.
- If increased platelet destruction or consumption is present, daily administration may be required.
Anemia is an important risk factor contributing to an increased risk of bleeding, particularly in thrombocytopenic patients and patients with acquired qualitative platelet defects such as uremia. Maintaining these patients’ hematocrits at higher levels contributes to improved hemostasis and decreased bleeding. Hemodynamic studies have demonstrated that at higher hematocrits, red blood cells predominate in the central portion of the bloodstream and push platelets peripherally where they are more readily available to interact with endothelium at sites of injury. For this reason, the laboratory recommends that if a patient is both anemic and thrombocytopenic, red blood cells should be transfused before platelets.
