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More on Mixing Studies and the RVVT

Hi George, I have a further question about “Interpreting a prolonged PT and PTT,” posted April 16. My question is, “what if the PT and PTT are prolonged and correct upon mixing with normal reagent plasma, but the Russell viper venom time (RVVT) is normal?” This question is part of a coagulation project I’m doing […]

Fibrinogenemia and Factor Assays

Here is a question I can’t answer, from Pam Owens at Tricore Laboratory in Albuquerque Hi, George. We are wondering at what point will an abnormally high fibrinogen start shortening the times of clot-based tests like factor assays. Specimens with low fibrinogens get some correction from the factor deficient plasma, but what about patients with […]

Follow-up From Prof. Munhoz

Dear Mr Fritsma, First of all I’d like to thank you very much for such a fast and clear answer. Sorry for my delay. It’s not actually a coincidence that Dr. Marques and I are from the same city. I attended Dr. Marques’ speech years ago here in Porto Alegre at UFRGS Clinicas Hospital. Since then […]

McGlasson ISTH Posters: Glucosamine and Chromogenic FVIII

I’ve just returned from the International Society on Thrombosis and Haemostasis biannual meeting in Boston, where I had the opportunity to assist Dave McGlasson with three posters: McGlasson DL, Fritsma GA. Platelet aggregation suppression by glucosamine supplement glucosamine McGlasson DL, Patino G, Shah AD, Rubal BJ. Study of platelet activity in routine and acute coronary […]

Automated D-dimer on a Lipemic Specimen

Hi George! I have a question. Recently, we were asked by the ER to perform a D-dimer to R/O a DVT on a sample that was lipemic. I would categorize it as grossly lipemic. We use the Stago which uses a method based on the absorbency of light passed through the reaction mixture. Could we […]

DRVVT: Not Prolonged, Positive Ratio

Here is an interesting question from Prof Terezinha Paz Munhoz: Mr Fritsma, Could you please help us? When the DRVVT screen is not prolonged, but the ratio of screen to confirmatory exceeds the established cutoff, what do we do? I’ve read a review by Teruya J, West AG, Suell MN. Lupus anticoagulant assays; questions still to […]

Quick Question: FVIII Inhibitor Assay Cutoff

Our June Quick Question asked, “Most laboratories perform a FVIII activity assay before starting a Bethesda titer for FVIII inhibitor. At what FVIII activity level do you cancel the order for the titer? a. 20% activity: 6 respondents, 35% b. 30% activity: 3 respondents, 18% c. 40% activity: 1 respondent, 6% d. 50% activity: 6 […]

Congresa Cientifico Deferred

To our disappointment, the IV Congreso Nacional de Microbiología, scheduled for July 1-3 at the Intercontinental Hotel Tegucigalpa, Honduras, has been deferred because of the political unrest that led to a coup and removal of President Zelaya on Sunday, June 28. The meeting will be held later when political concerns become stabilized. Please watch here for […]

Quick Guide to Coagulation; 2nd Edition

In shameless self-promotion, I want to announce that our Quick Guide to Coagulation, 2nd Edition is now available from AACC Press and from the American Society for Clinical Laboratory Science. The new edition is expanded from 62 to 108 pages and includes a section on platelet aggregometry and a series of speedy reference tables. The Quick Guide is still […]

Does Actin FS Introduce a FVIII or FIX Assay Bias?

Here is an interesting question about Actin FS sensitivity for coagulation factors VIII and IX from Vanessa Chan at SickKids Hospital in Toronto: I’m currently working on the validation of the Stago Sta-R Evolution. Throughout this process, I have run into a couple of problems with my FVIII and FIX assays. Using Siemens Actin FS, Stago Unical calibrator […]

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George Fritsma is a medical laboratory scientist, educator, and author. George is a member of the International Society on Thrombosis and Hemostasis, the International Society for Laboratory Hematology, and the American Society for Clinical Laboratory Science.

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