Pre-examination issues (part three in a series) affecting platelet function testing are highlighted in the Focus Article.  Test results from low (aggregometry) and high (PFA-100®) shear systems can be significantly impacted by variability associated with specimen collection & handling as well as sample preparation & storage.  Additionally, a CLOT-BYTE takes a ten year journey through the evolution of ADAMTS-13 activity assays.  Activity of the protease, in the absence or presence of inhibitory antibodies, is pertinent to making a diagnosis of thrombotic thrombocytpenic purpura (TTP).

Dr J Evan Sadler, an international expert on Von Willebrand Factor/Disease, is the guest author for a Focus Article wherein he describes how the Von Willebrand Factor cleaving protease, ADAMTS13, influences the phenotype of Von Willebrand Disease and Acquired Von Willebrand Syndrome.  In addition, a History & Trivia section provides a timeline of discoveries in VWF/VWD, another section updates us on changes to the 1994 VWD classification, and in the final feature the laboratory’s armamentarium for assays used in making the diagnosis of VWD is discussed.

Dr Jerry Ware guest authors the Focus Article which challenges us to think beyond our customary understanding of the role that platelets perform in hemostasis & thrombosis and to consider them as players in other areas such as cardiovascular disease, tumor metastasis, and neurological disorders.  Other features include: 1) three tables for ISO 15189:2003 International Standard elements relating to Management Requirements, 2) an article on how clot-based factor assays are performed, and 3) a Lab Pointer on the making of dilutions.