Anticoagulant Therapy

Reptilase Time

I received this question on 9/14/24: Hello George, Is there any condition where reptilase time is prolonged while thrombin time is normal? My answer is, in a word, no. The thrombin time (TT, or TCT) typically uses 50–100 mg topical human or bovine thrombin, mixed 1:1 with plasma. A normal plasma/thrombin mix clots within ~20 […]

Bleeding Disorders

Prolonged DRVVT Screen

Soha Abuelela asked how to report a DRVVT screen above 120 seconds and how to report the ratio. I [Geo] consulted with my colleague Dave McGlasson. We began by assuming that 120 seconds represents your instrument’s limit and that the actual clotting time was unrecorded. It could be that your specimen has an undetected clot […]

Anticoagulant Therapy

VKA Monitoring in Hepatic Insufficiency

Here is a challenging case from Hrvoje Melinšćak sent 5-30-24: Dear George, In hepatic insufficiency there is often a prolonged basal protime, how to ensure therapeutic values of warfarin when the INR is already elevated? This is of particular concern in those with mechanical cardiac valves. Serum warfarin levels (spectrophotometry) are cumbersome and take days to […]

Establishing the PTT-based UFH Therapeutic Range

A March 22 entry from Robyn Coleman, Senior Scientist, Coagulation, Haematology, Sullivan Nicolaides Pathology, Queensland, Australia: Dear George, I am seeking some direction on APTT therapeutic ranges for UFH. We are facing a change to our APTT reagent. The cohort of patients we would have traditionally used to validate UFH therapeutic range (TR) for APTT, […]

Anticoagulant Therapy

Anti-XI Anticoagulant

Here is a transcript of an interview with Christian T. Ruff, MD, Senior Investigator, Thrombolysis in Myocardial Infarction (TIMI) Study Group, Boston, Massachusetts,USA describing the favorable AZALEA-TIMI Phase 2 safety study of a monoclonal anti-XI once-a-month injectable anti-XI anticoagulant, abelacimab.

Anticoagulant Therapy

In Vitro DOAC Removal Agents

Wenxiong He [“Wen”], Toronto, Canada, is a participant in the Rutgers University graduate course CLSC 5124, Advanced Hemostasis. Wen is in the hematology lab at St. Michael’s Hospital in Toronto which includes the special coagulation lab. Wen offered this information about the use of a DOAC removal agent: “Our lab uses a DOAC removal product […]

Anticoagulant Therapy

Anti-Xa Dilution

Marietta Tomlin asks, Can Owren-Koller buffer be used instead of normal plasma to dilute anti-Xa when the are results above linearity? And if not, can you provide information on the reasoning/mechanisms as to why not? From LaShanta Brice, DCLS, MLS (ASCP)cmSH (ASCP)cm Scientific Engagement & Clinical Education Associate, Diagnostica Stago, Inc. Because our assay uses […]

Anticoagulant Therapy

Mixing Studies and Various Therapeutics

From Leslie Chaparro: We recently had a patient who had a mixing study ordered but who had recently taken tranexamic acid [TXA]. We exclude patients that have been on anticoagulants but have never really considered drugs that encourage clotting. How would this affect the patient’s mixing study? How do we keep up with all the […]

Anticoagulant Therapy

Precision BioLogic Poster at ISTH: DOAC-Remove

You are invited to visit the ISTH poster submitted by Precision BioLogic Inc.: PB1147 Effect of high-dose direct anticoagulant drugs and DOAC-Remove on lupus anticoagulant detection by a hexagonal phase phospholipid assay. The poster goes up Tuesday, 27 June 2023, 18:30–19:30.

Specimen Management

May 2023 Quick Question: DTI

Our May 2023 Quick Question asks, “Which DOAC is a direct thrombin inhibitor? Our 70 respondents chose… Dabigatran [Pradaxa]: 56 [80%] Rivaroxaban [Xarelto]: 3 [4%] Apixaban [Eliquis]: 3 [4%] Warfarin [Coumadin]: 7 [10%] Clopidogrel [Plavix]: [2%] Dabigatran is the direct thrombin inhibitor, whereas rivaroxaban and apixaban are direct anti-Xa inhibitors. Clopidogrel is an antiplatelet antithrombotic. […]

Quick Question Archive

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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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