Here is a summary of our July, 2012 Quick Question: How do you assay for von Willebrand factor (VWF) activity? a. VWF ristocetin cofactor (VWF:RCo) by aggregometry: 21 (34%) b. Automated VWF ristocetin cofactor (VWFRCo): 21 (34%) c. VWF activity immunoassay (VWF:Act): 15 (25%) d. Collagen binding assay (CBA): 4 (7%) It seems the collagen […]

There’s a definitive article in the June, 2012 JTH that describes the three methods currently available to assay von Willebrand factor activity: ristocetin cofactor (VWF:RCo), collagen binding (VWF:CB), and a monoclonal antibody-based immunoassay (VWF:Act). See Favaloro EJ, Bonar R, Chapman K, Meiring M, Funk (Adcock) D. Differential sensitivity of von Willebrand factor (VWF) ‘activity’ assays to large […]

Here’s a summary of our June, 2012 Quick Question: To perform the chromogenic anti-Xa heparin assay, how many separate reference curves do you maintain for unfractionated (UFH), low molecular weight (LMWH) heparin and fondaparinux? a. One hybrid curve for UFH and LMWH, same curve (computed) for fonda: 7 (16%) b. One hybrid curve for UFH […]

Here are the responses to our May, 2012 quick question: When using point of care testing, at what INR does your anticoagulation clinic require a confirmatory plasma-based (conventional) PT? a. 4.0: 34 (65%) b. 5.0: 9 (17%) c. 6.0: 4 (8%) d. Never: 5 (10%) Our responses closely parallel our April 24 and May 7 discussions; […]

Here is a summary of our April, 2012 Quick Question: The US FDA is planning guidelines for regulating laboratory-developed tests (LDTs). What plans have you made in response? a. We are discontinuing all LDTs: 3 (15%) b. We didn’t know this is happening: 11 (55%) c. None, this will only apply to reference laboratory LDTs: 1 (5%) […]

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