The platelet-reactivity-test — A useful “by-product” of the blood-sampling procedure?

Blood sampling demands the insertion of a needle into the blood-vessel thereby causing a destruction of the endothelial wall of the blood-vessel. The physiological reaction of platelets is the occlusion of endothelial lesions. Reaction of platelets induced by endothelial lesions lasts about 10 ms. Each blood sampling procedure should therefore activate platelets. A simple platelet test-system was designed following these considerations. Blood samples were collected twice, in EDTA-buffer and in EDTA-formalin-buffer. Activated (aggregated) platelets were fixed by formalin or dissolved in EDTA-buffer. Platelet-reactivity (PR) was calculated as quotient of the number of platelets remaining in the supernatant of both samples after centrifugation. The PR-index-values strongly depended on the blood-sampling procedure. Standardization of the blood sampling procedure led to normal distributed PR-index-values in 110 healthy controls (0.98 ± 0.09). PR-index-values remained constant during a period of 260 days. PR-index-values in 49 patients suffering from encephalomyelitis disseminata were 1.04 ± 0.15 and 1.64±0.6 in 72 patients suffering from transitoric ischemic attacks. Differences between healthy controls and patients suffering from TIA's were significant (p