From Debbie Moffitt in Honolulu:
Someone brought up a question regarding platelet testing with the PFA-100. As far as I know, we are concerned about prolonged results, but is a result less than the normal range normal or abnormal? Should we be concerned about a hypercoagulable state? What would be the appropriate action? Would we ask for a redraw or what kind of comment
should be made with the results, if reported?
Deborah Moffitt MT (ASCP)
Diagnostic Laboratory Services
Queens Medical Center
Honolulu, Hawaii
Hi, Debbie, and thank you for your question. Have you seen a number of shortened PFA-100 results, or is this more a hypothetical question? Actually, I know of no significance for shortened PFA results, none have ever been correlated with platelet hyperaggregability or thrombophilia, though the possibility is intriguing. There are several publications, many by the late Dr. E Mammen of Wayne State University, Detroit, that define platelet hyperaggregability as an aggregation response to reduced ADP or epinephrine agonist concentrations. These have been correlated to a number of arterial thrombotic events, although mostly by individual case study historical review. In none of these have I seen the PFA-100 compared to aggregation results, however.
Hi Debbie (& George),
Indeed, a short PFA-100 closure
Hi Debbie (& George),
Indeed, a short PFA-100 closure time result has been proposed as a possible marker of ‘thrombophilia’, and will arise when (for example) there is a high level of VWF (or more likely a high level of high molecular weight VWF as for example measured by the collagen binding assay). I note that you recently posted a note on a paper that reported that high plasma VWF levels were associated with future adverse cardiovascular events in patients with AF. Can I also suggest the following papers from Seminars in Thrombosis and Hemostasis: 1. Favaloro EJ. Clinical utility of the PFA-100. Semin Thromb Hemost. 2008 Nov;34(8):709-33. 2. Franchini M, Mannucci PM. Von Willebrand factor: another janus-faced hemostasis protein. Semin Thromb Hemost. 2008 Oct;34(7):663-9. The first has a section on the association of short PFA-100 closure times with thrombosis, and the second discusses the possible role of (elevated) VWF as a prothrombotic factor. I guess I do not need to mention TTP, as another good example of VWF-mediated thrombosis. Perhaps we should test patients with TTP with the PFA-100?