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D-dimer Efficacy in Factor V Leiden Mutation

This 6/30/2012 question from a physician arrived through the American Society for Clinical Laboratory Science Consumer Web Forum. “Does delayed fibrinolysis in a known factor V Leiden (FVL) mutation patient reduce the value of a negative D-dimer test?” George’s initial response: Thank you for your question. I was prepared to answer that there is no connection, […]

Antiplatelet Therapy and Cardiac Surgery

A question from my colleague and our former graduate student, Rebecca Jones: Hey, George. When patients are sent to general surgery or to have a stent put in, how much inhibition of platelets is acceptable for procedures to be performed? We have been doing a calculation giving surgeons percent inhibition, but are being asked to switch […]

Anticoagulant Therapy

Low Factor VIII Reporting

Hi, Using the ACL 9000, we have seen some low results for the factor VIII activity test, as low as 0.3%. In those instances we were told to dilute the sample 1:2, and retest. On those retests we get the same results, should we report the result as it is or with a less than […]

Panic Value: INR or PT?

Hi, We run coagulation tests at my work place on an ACL 9000 from Instrumentation Laboratory and I would like to know what should be considered as a panic value, a high prothrombin time (PT) value or the international normalized ratio (INR) value? If it is the PT value, what value should be considered as […]

Anticoagulant Therapy

UFH Infusion: a Max Dose

This question was forwarded to me by my friend and colleague, Marisa Marques, MD, Director of the University of Alabama at Birmingham Hospital special coagulation laboratory and transfusion service: “One of our pharmacists asked if there was a maximum dose for the heparin bolus or infusion rate for obese patients since our current recommendations are based on body […]

Anticoagulant Therapy

New Anticoagulants in AF

Guidelines for Coumadin, aspirin, dabigatran (Pradaxa), rivaroxaban (Xarelto), and apixaban (Eliquis) are changing rapidly, favoring the new oral anticoagulants in most cases of atrial fibrillation. See the current TheHeart.org discussion based on “CardioStim 2012 in Nice, France. Geo

Anticoagulant Therapy

New Quick Question: VWF Activity Assays

There’s a definitive article in the June, 2012 JTH that describes the three methods currently available to assay von Willebrand factor activity: ristocetin cofactor (VWF:RCo), collagen binding (VWF:CB), and a monoclonal antibody-based immunoassay (VWF:Act). See Favaloro EJ, Bonar R, Chapman K, Meiring M, Funk (Adcock) D. Differential sensitivity of von Willebrand factor (VWF) ‘activity’ assays to large […]

Bleeding Disorders

Calendar of Coagulation Conferences

Our web site maintains an up-to-date calendar of coagulation conferences around the world. Check in occasionally to learn what is happening in your area.

QQ: Anti-Xa Heparin Assay

Here’s a summary of our June, 2012 Quick Question: To perform the chromogenic anti-Xa heparin assay, how many separate reference curves do you maintain for unfractionated (UFH), low molecular weight (LMWH) heparin and fondaparinux? a. One hybrid curve for UFH and LMWH, same curve (computed) for fonda: 7 (16%) b. One hybrid curve for UFH […]

Anticoagulant Therapy

Heme Binds Factor VIII

There is a thought-provoking article in the June, 2012 issue of Journal of Thrombosis and Haemostasis: Repesse Y, Dimitrov JD, Peyron I, et al. Heme binds to factor VIII and inhibits its interaction with activated factor IX. J Thromb Haemostas 2012;10:1062–71. The authors do not speculate on in vitro specimen hemolysis, however their findings could provide additional […]

Specimen Management

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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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