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Platelet rosetting, or satelliting, around white blood cells can lead to undercounting by automated analyzers. [5] Clotted samples. Coagulation within the sample leads to undercounting, because the analyzer samples the liquid part of the blood, while some of the platelets remain in the tube, trapped in the clot.
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.
In an unknown fashion, the antibiotic ristocetin causes von Willebrand factor to bind the platelet receptor glycoprotein Ib (GpIb), so when ristocetin is added to normal blood, it causes agglutination of fixed platelets or initiates the initial agglutination phase of aggregation of live platelets. [citation needed]
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]
Platelet concentration in the blood (i.e. platelet count), can be measured manually using a hemocytometer, or by placing blood in an automated platelet analyzer using particle counting, such as a Coulter counter or optical methods. [47] Most common blood testing methods include platelet count in their measurements, usually reported as PLT. [48]
A rapidly declining platelet count; High levels of fibrin degradation products, including D-dimer, are found owing to the intense fibrinolytic activity stimulated by the presence of fibrin in the circulation. The peripheral blood smear may show fragmented red blood cells (known as schistocytes) due to shear stress from thrombi. However, this ...
SPS is diagnosed by demonstrating platelet hyperaggregability. In a lab test called aggregometry, platelet stickiness is stimulated with epinephrine (EPI) and/or adenosine diphosphate (ADP). [12] This test is not possible for patients being treated with acetylsalicylic acid until that substance has sufficiently cleared from their system.
This results in platelet activation and the formation of platelet microparticles, which initiate the formation of blood clots; the platelet count falls as a result, leading to thrombocytopenia. [1] [7] In addition, the reticuloendothelial system (mostly the spleen) removes the antibody-coated platelets, further contributing to the thrombocytopenia.