Factor Assays

Quick Question: 6 YO Boy with Chronic Bleeding

Please click or tap our December 31, 2018 Quick Question post, a case study of a 6-year-old boy with chronic bleeding. We had a 2018–19 record 76 responses. The choices and responses are as follows. Answers Platelet function abnormality: 10 (13%) Von Willebrand disease: 14 (18%) Factor VII deficiency: 4 (5%) Factor XII deficiency: 4 […]

Bleeding Disorders

Nijmegen-Bethesda Assay

Beginning with a 2016 Quick Question and continuing to our most recent post in March, 2018, we’ve devoted altogether six entries to the 2012 CDC refinements of the Nijmegen-Bethesda assay. These have culminated in the following material, which appears in Fritsma GA, Chapter 41, Laboratory Evaluation of Hemostasis; in Keohane EM, Otto C, Walenga JM. […]

Bleeding Disorders

Quick Question: Extrinsic Pathway

Our September, 2018 Quick Question was a quiz with one correct answer addressing our knowledge of the coagulation cascade: Which coagulation factor is the first activated in the extrinsic pathway? With 144 responding, the answers were: Factor XII: 16 (11%) Factor IX: 9 (6%) Factor VII: 105 (73%) Prothrombin: 14 (10%) Congratulations to the overwhelming […]

Coagulation Factors

Modified Nijmegen-Bethesda Assay

Precision BioLogic Inc. presented MNBA data at the World Federation of Hemophilia (WFH) 2018 World Congress in Glasgow, Scotland, May 20–24. Recognizing the need to improve factor VIII (FVIII) inhibitor testing for people with hemophilia A, the company studied the agreement between a chromogenic modified Nijmegen-Bethesda assay (MNBA) and a qualitative ELISA test in the […]

Bleeding Disorders

Nijmegen Bethesda Assay

Dr. Ali Sadeghi-Khomami, Precision BioLogic Inc., provided these in-depth technical questions about the Nijmegen Bethesda Assay (NBA), which we use to quantitate specific factor inhibitors such as anti-factor VIII or anti-factor IX. George forwarded his questions to Connie Miller and Amanda Payne, US Centers for Disease Control and Prevention (CDC) who have been working on […]

Bleeding Disorders

Factor Substitution Assays

George occasionally receives questions about factor substitution assays. We coagulationists of a “certain age” can recall preparing barium sulfate or aluminum hydroxide “adsorbed” plasma, aged plasma, and serum, then performing mixing studies on prolonged PTT patient plasmas. We mixed the patient plasma 1:1 with pooled normal plasma and the adsorbed and aged plasma and serum, […]

Quick Question Results: Bethesda Titers

The results of our latest Quick Question are in with 87 responses.. How does your laboratory measure factor inhibitors? Standard Bethesda assay: 33% (26) Bethesda titer using buffered pH 7.4 pooled normal plasma: 9% (8) Nijmegen Bethesda assay using factor-depelted plasma as diluent: 9% (8) CDC modification of Nimegen Bethesda assay: 0% (0) Bethesda chromogenic […]

Bleeding Disorders

Chilling The NBA Reaction Mixture

From Dr. Mirta Arias: Dear George, Thank you for your answer in the blog. I have another question. Dr. Robinson in ISLH argued that it is good to chill the post 2 hour/37°C 37 incubation mixtures of patient + pool normal plasma, and control at 2–8°C for 10 minutes and then measure the factor VIII. In […]

Bleeding Disorders

Nijmegen Bethesda Assay

From Dr. Mirta Arias, Dear George, which is the procedure for determining the cut-off of Bethesda method and Nijmegen? Is there any Excel spreadsheet to perform it? Do you use only normal or normal and patients? Thanks, Mirta Hello, Dr. Arias, and thank you for your question. For a comprehensive answer, I turned to Amanda […]

Bleeding Disorders

Nijmegen-Bethesda Assay Method

Sarah Payne and Kerri Klemm request information on how to perform the CDC modification of the Nijmegen-Bethesda Assay for coagulation factor inhibitors. Thank both of you for your request, which provides George the opportunity for self-promotion. Please tap or click Coagulation Factor Inhibitors and the Nijmegen Bethesda Assay, a recording of my June 2 digital […]

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.

Cheat Sheets from George

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