Bleeding Disorders

QQ: VWF Activity

Here are the results of our January, 2018 Quick Question. Stem: What method do you use to measure von Willebrand factor activity? a. Ristocetin cofactor (VWF:RCo): 61% (32) b. Collagen binding assay (VWF:CB): 6% (3) c. VWF activity immunoassay (VWF:Act): 23% (12) d. Ristoectin-triggered recombinant GP 1b immunoassay (VWF:GPIbR): 4% (2) e. Non-ristocetin gain of […]

Bleeding Disorders

Factor IX Assay News Release

George has attached a Precision BioLogic Inc. news release describing the outcomes of factor IX assay studies conducted with Sobi. The data were published in poster format at 11th Annual Congress of the European Association for Haemophilia and Allied Disorders (EAHAD). Thanks to Elaine Benoit, Precision BioLogic for the heads-up, and to Ali Sadeghi-Khomami PhD […]

Bleeding Disorders

VWF:RCo Interference

From Jasmina Ahluwalia, MD: Hello George, We use the IL vWF Antigen (VWF:Ag) and vWF Ristocetin Cofactor (VWF:RCo) activity kits on the ACL TOP 500 analyser. Lately, I have noticed that in nearly 5% of the samples tested we have VWF:RCo activity levels that are much higher than the antigen levels. We have repeat tested […]

Bleeding Disorders

Yet More on Reference Intervals

This is a follow-up comment from Bob Gosselin on Griselle Font-Bonet’s December 31 post about reference intervals. The original post drew many thoughtful and provocative comments from Dave McGlasson, and Drs. Ali Sadeghi-Khomami and Emmanuel Favaloro; consequently, it became so long that an add-on comment would make it unwieldly. Bob says these “last thoughts”… Lest […]

Bleeding Disorders

Bleeding Diathesis Discussion Part 3: QPD

This discussion of Quebec Platelet Disorder (QPD) is in response to Dr. Ari Elman’s undiagnosed bleeding diathesis case and expands on the comment by Dr. Emmanual Favaloro. QPD is a functional disorder caused by autosomal dominant duplication of the PLAU gene located on chromosome 10. PLAU codes for platelet urokinase (urinary plasminogen activator, uPA), and […]

Bleeding Disorders

Bleeding Diathesis Discussion Part 2

Additional responses to Dr. Ari Elman’s undiagnosed bleeding diathesis case. Recalling that in Dr. Elman’s case review, the patient denies using supplements, these comments nevertheless point to a diet-based acquired platelet disorder and suggest that the patient may have under-reported her use of supplements, a common occurence. From Ali Sadeghi-Khomami, PhD, Scientific Director, Precision BioLogic: […]

Bleeding Disorders

Bleeding Diathesis Discussion Part 1

We received several responses to Dr. Ari Elman’s 12/20/17 Undiagnosed Bleeding Diathesis post. This post begins a summary of possibilities. From George Fritsma, moderator, given that the patient’s platelets fail to secrete in response to ADP, epinephrine, and arachidonic acid, could this be an acquired platelet activation pathway enzyme deficiency? Could she have developed an […]

Bleeding Disorders

Case: Undiagnosed Bleeding Diathesis

From Dr. Ari Elman, Hematology and Medical Oncology, Sandra & Malcolm Berman Cancer Institute, Greater Baltimore Medical Center: I asked you a question last month and was quite impressed with the thorough response and the team of experts you had weigh in. I have an extremely difficult case with a young woman, just 22 years old, who […]

Bleeding Disorders

Automated Bethesda Titre

From Jasmina, Department of Hematology, Postgraduate Institute of Medical Education and Research, Chandigarh India Hello George. This is regarding running the factor VIII assay for the Bethesda assay on automated analysers. When performing the Bethesda assay on the coagulation analysers like the ACL TOP (IL), we make the doubling dilutions of sample and add them […]

Bleeding Disorders

Monitoring Extended Half-life Factors

From Allen Quigley, Hematology/Coagulation Technical Specialist, Children’s Hospitals and Clinics of Minnesota. George, what is the best way to measure factor VIII and IX levels on patients that are being infused with different products? We perform one stage clotting assays using Actin FSL, which is an ellagic acid activator, and other labs may use reagent […]

Bleeding Disorders

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George Fritsma is a medical laboratory scientist, educator, and author. George holds faculty appointments with Rutgers University and Michigan State University, and is a member of the International Society on Thrombosis and Hemostasis, American Association of Clinical Chemists, and American Society for Clinical Laboratory Science.

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