Platelet adhesion assay--a new quantitative whole blood test to measure platelet function

At this time no practical laboratory method for the measurement of the current functional state of blood platelets is available. A new innovative platelet adhesion assay (PADA) is described here. With only a short time requirement and minimal equipment, the PADA provides quantitative measurements of platelet adhesiveness. Only 0.5 mL of freshly drawn citrated whole blood is needed, to which special polymer particles are added. A defined shear grade is induced by a short period of shaking the sample. Proteins of the blood sample, especially fibrinogen, and thereafter also activated platelets, bind to the specific polymer surface. Following platelet counts both in the sample and in a control (blood without particles), the adhesion index (AI) is calculated as a quantitative measure of platelet adhesiveness. In healthy volunteers, a mean AI of 52+/-12 was measured. AI was shown to be nearly independent of the number of platelets in the sample (100 to 350 k/ microL), the hematocrit (44 to 25%), and the fibrinogen content (1.5 to 5 g/L). Age of the volunteers had only a minor influence on the AI. PADA was shown to be a simple reliable laboratory method for the detection of disturbed platelet function. The test requires low analytical efforts compared with other diagnostic platelet function tests.