From Kathy Doig, PhD, Michigan State University (Go Spartans!). George – what is the current thinking on how antiphospholipid antibodies (lupus anticoagulants, LAs) interfere with our assays? Does the antibody physically block the proteins so they can’t react properly even though they embed in the phospholipids (PLs)? Does it prevent them from embedding in the PLs as they should? Or is it something else entirely?
Dr. Doig gets these penetrating questions from her graduate students, sending us back to the books for answers. Here is George’s effort at a reply:
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In follow-up to Lisa Bakken’s June 19, 2014 question, here is Cunningham, MT, Olson JD, Chandler WL, el al. External quality assurance of fibrinogen assays using normal plasma; results of the 2008 College of American Pathologists Proficiency Testing Program
in Coagulation, Arch Pathol Lab Med 2012;136:789–95. This report was provided by a colleague, and addresses the dispersion of CAP survey fibrinogen results among various instrument/reagent combinations.
Click here for the article: Cunningham et al 2012.
Biogen Idec released Alprolix®, their prolonged circulation recombinant factor IX concentrate soon after it was cleared by the FDA, March 28, 2014. Alprolix may be administered as little as once a week when used for factor IX deficiency (Hemophilia B) prophylaxis. The concentrate’s pharmacokinetics and efficacy were established using the partial thromboplastin time (PTT), identified as the “one-stage clotting assay (OSC)” by the distributor.
Buyue Y and Sommer JM, Biogen Idec, presented the poster referenced in the attached abstract at the International Society on Thrombosis and Hemostasis Standardization Subcommittee meeting in Milwaukee, June 23–25, 2014 describing the relative sensitivities of three PTT reagents, one each using ellagic acid, kaolin, or silica and concluded the ellagic acid-based is more sensitive than the others, indicating that the type of PTT reagent you use profoundly affects your factor assay results. Read more »
From Kelly Townsend, Tri-core Reference Laboratories, Albuquerque. Looking for opinions on what constitutes a “Laboratory Developed Test” in Coag. Obviously if the reagent kit is not FDA-cleared, it will be an LDT, but what about factor assays, etc where there is no real kit. What if you are using a kit with a different calibrator or control than the manufacturer sells/endorses? Having trouble coming up with a concise definition for LDT. Thanks, Kelly.
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From Lisa Bakken:
I am a part of a stroke committee at my hospital that needs/wants to implement anti-factor Xa and anti-factor IIa testing for the new oral anticoagulants (NOACs). In addition to this, our laboratory is looking into new coag instrumentation. We are struggling to determine what is the best for our patient population. Our geriatric population is particularly high so the need for monitoring anti-thrombolytics and stroke work-ups will be high.
Hemostasis is not my strong suit and I value your opinion. May I ask what instrumentation do you use in your laboratory? We currently have a CA-1500 from Siemens and we were looking at the Stago STA Compact Max. Are you familiar with either platform? Do you think the Stago reagents for the NOACs are better or worse than what Siemens has? Which methodology do you feel is more accurate, optical or mechanical? It’s always difficult when trying to discern information from sales representatives from both companies. Any insight you can give would be appreciated.
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The International Society on Thrombosis and Haemostasis Scientific and Standardization Subcommittee meets June 23–26 at the Wisconsin Center, Milwaukee, Wisconsin. Please stop by to meet George and our folks at the Precision BioLogic booth, #308. See you in Milwaukee!
We’ve just updated our 2014–2015 conference calendar. Also updated is our list of fellow organizations with links to their sites. If your conference or organization does not appear, please provide a response below and it will be posted.
From Dave McGlasson, George, Has anyone got information on storing DRVV screen and confirm reagent aliquots? Can you freeze/thaw them without any loss in activity? That question has come up to me recently.