STUDIES OF THE PLATELET FILTER TEST (SHEAR DEPENDENT PLATELET-AGGREGATION) IN PATIENTS WITH UNCOMMON HEMORRHAGIC DISORDERS

Platelets of anticoagulated whole blood forced at 40 mmHg through a fi ne filter are activated, aggregated and retained, so block the filter (platelet filter test, O'Brien JR, Salmon GP. Blood 1987; 1354-1361). Our clinical experiences with this simple and quick haemostasis test a re summarized Patients were investigated with different types of vWD ( type-1=35, type-2A=7, type-2B=7, type-3=1), Glanzmann's thrombasthenia , congenital deficiency of cyclco-oxygenase, acquired Bernard-Soulier syndrome, FXII-, FXIII-deficiency and a control group. The cumulative drop count and the platelet retention were carefully measured during t wo phases of the filter test. Platelet count, bleeding time, vWF:Ag an d vWF:R of activity were measured along with the platelet filter test. The filter was not blocked and the platelet retention was abnormally low in all patients with thrombasthenia, type-2a, type-2B, type-3 vWD, Treatment with 1-desamino-8-D-arginine-vasopressin (DDAVP) caused enh anced platelet retention in 16 patients with type-1 vWD. The test is s imple, quick and cheap, has good reproducibility, and may be useful in clinical haemostasis laboratories for examination of high shear induc ed platelet functions.