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In a typical set of rules, a platelet donor must weigh at least 50 kg (110 lb) and have a platelet count of at least 150 x 10 9 /L (150,000 platelets per mm³). [2] One unit has greater than 3×10 11 platelets. Therefore, it takes 2 liters of blood having a platelet count of 150,000/mm³ to produce one unit of platelets.
They form aggregates with white blood cells and in adults the platelets that are bound to white blood cells are usually activated. In children, these white blood cell-platelet aggregates are increased in children compared to adult levels, however this takes place without a corresponding increase in platelet activation. [ 10 ]
Two reviews in people with blood cancers receiving intensive chemotherapy or a stem cell transplant found that overall giving platelet transfusions when the platelet count is less than 10 x 10 9 /L compared to giving platelet transfusions when the platelet count is less than 20 or 30 x 10 9 /L had no effect on the risk of bleeding. [14] [18]
Platelets are regulators of hemostasis and thrombosis. Platelets become active in the blood following vascular injury. Vascular injury causes platelets to stick to the cellular matrix that is exposed under the endothelium, form a platelet plug, and then form a thrombus. Platelets are essential in the formation of an occlusive thrombus and are ...
A study observed that compared to the four weeks before September 11, there was an estimated increase of 18,700 donations from first-time donors for the first week after the attack: 4,000 was the average of donations from first-time donors before the attack which increased to about 22,700 donations; while repeat donors increased their donations ...
The red blood cells are denser than plasma and the other present blood cells (platelets, white blood cells) and settle at the bottom of the blood bag. After centrifugation, the red blood cells are separated from the other components (the majority of the plasma, platelets and white blood cells) through the use of an extractor (also referred to ...
One common definition of thrombocytopenia requiring emergency treatment is a platelet count below 50,000/μL. [5] Thrombocytopenia can be contrasted with the conditions associated with an abnormally high level of platelets in the blood – thrombocythemia (when the cause is unknown), and thrombocytosis (when the cause is known). [6] [7]
Platelets for transfusion can also be prepared from a unit of whole blood, whereby 4 or 5 buffy coats are pooled to produce a platelet component. Some blood banks have replaced this with platelets collected by plateletpheresis because whole blood platelets, sometimes called "random donor" platelets, must be pooled from multiple donors to get ...