Here is a message from Carol Houde of Emerson Hospital:
I’m interested in the association between elevated factor XI activity and the lupus anticoagulant. When doing dilutions how do you effectively differentiate between the “lupus effect” on this PTT-based assay (especially when the LA result is borderline positive)?
Hi, Carol. Sorry to say, I know of no relationship between elevated factor XI and lupus anticoagulant prolongation of the PTT. I do know if you attempt a PTT-based assay of VIII, IX or XI in a lupus anticoagulant positive plasma you are likely to get a false reduction. I’m posting this question for assistance from our subscribers.
A question from Delphine in France about prekallikrein (PK, Fletcher factor) deficiency measurement:
is there a difference between the PTT with kaolin versus silica to measure PK deficiency? What is the impact of incubation time? It seems PTT with kaolin doesn’t work well to measure PK?
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Our participants apparently support some of the principles of the controversial new ISTH lupus anticoagulant testing guidelines; Pengo V, Tripodi A, Reber G, et al. Update of the guidelines for lupus anticoagulant detection. J Thromb Haemost 2009; 7: 1737-40. Here are the answers for our October Quick Question:
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Quest Diagnostics and Nichols Institute have just announced their March 17-19, 2010 Case Oriented Thrombosis and Bleeding Symposium at the Hyatt Regency, Reston; Reston, VA.
From Stacy at the University of North Dakota:
George, Can you tell me about Factor P? Stacy
Stacy, I believe factor P is a name for properdin, the triggering molecule of the alternate complement pathway. I don’t know much about properdin, but if you have a follow-up question, I’ll be happy to take a shot at it. Geo.
Here is a note about the ecarin time from Twyla Bader:
George, how commonly is the ecarin time being used to monitor hirudin during surgery? Also is there any device that performs this superior compared to others?
Thank you, Twyla Bader
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I will present “Hemophilia Therapy: Rasputin to Recombinants” at the Northeast Laboratory Conference, Thursday, October 22, 1:30-3:00 PM at the Portland Holiday Inn by the Bay, Portland, Maine. My talk includes an overview of hemophilia inheritance, pathology, treatment and factor inhibitors. It then moves to hemophilia history including the story of Tsarovich Alexis of Russia, 1904-1918 and holy man Rasputin, development of effective treatments in the 1960s and 1970s, the impact of AIDS in the 1980s, and the subsequent development of recombinant factors preparations. PDF handouts (updated 10/23/09) for my talk are attached in the two per-page format, Hemophilia Therapy, Rasputin to Recombinants (2) or the six-per-page format, Hemophilia Therapy, Rasputin to Recombinants (6).
I will present “Does Aspirin Work?” at the Northeast Laboratory Conference, Wednesday, October 21, 10-11:30 AM at the Portland Holiday Inn by the Bay, Portland, Maine. My talk includes a discussion of clinical efficacy for aspirin, clopidogrel (Plavix), and the newly release Eli Lilly antiplatelet drug prasugrel (Effient). We’ll discuss means for detecting and resolving aspirin and clopidogrel resistance. Please select “Does Aspirin Work?” the to see and download the handout in 2-per-page format. Please use this link: Does Aspirin Work2? if you prefer the 6-per-page format. Geo.
Coagulation Factor Assays, Thrombophilia Testing | GeorgeFritsma | 
October 31, 2009 3:42 am | 
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