Determination of platelet factor 3 by thrombin generation using a micro-coagulation assay

Platelet factor 3 activity is usually determined by the Stypven method in which factor Xa generation is measured indirectly. The determination is dependent on factors I, II, V, X in the test sample. A coagulation assay for platelet factor 3, which measures the thrombin generation promoted by platelet factor 3, is presented. The test depends on platelet factor 3 only, because factors II, Xa, V, fibrinogen and Ca++ are added in excess. The usability of the new method is shown by platelet factor 3 determinations in patients with various platelet diseases, after ingestion of aspirin and in samples of platelet concentrates before and after storage.