Inherited and Acquired Disorders of Platelet Function

Platelet function defects are caused by rare congenital or, more frequently, by acquired disorders. They may lead to bleeding or thrombotic tendencies despite of normal platelet counts. The corresponding symptoms are often quite heterogeneous. A disorder of platelet function is suspected on the basis of case and family history, physical examination and platelet function tests. The so far primary screen of platelet dysfunctions, the bleeding time, is neither very sensitive nor specific and depends very much on the skills of the person that performs the test. Therefore, other general and in addition more specialised laboratory tests have to be performed for diagnosing an isolated platelet abnormality or in most cases combined platelet function defects. An approach to diagnosing a platelet disorder is presented, which supports the high significance of flow cytometry in platelet function analysis. Furthermore, we like to elucidate that in most cases a platelet-mediated haemostatic disorder cannot be characterised by just a single function defect, but rather by a combination of platelet functional abnormalities. Detailed knowledge of the platelet disorder is necessary for adequate therapeutical management of the individual patient, including the control of the underlying disease in acquired disorders, transfusion of platelets and administration of haemostatic drugs.