Anticoagulant Therapy

Dabigatran Gene Variant

Here’s a new outcome from the Dabigatran etexilate RE-LY study that suggests there is a gene variant in 1/3 of Caucasians that converts less of the prodrug, reducing the risk of bleeding without reducing efficacy.

Anticoagulant Therapy

PT/INR Results Using ISI 1.0 Reagents

From Terezinha Paz Munhoz: we started to use recombinant thromboplastin,RecombiPlasTin 2G (ISI 1.0) on our IL ACL TOP 500. The PT results are quite different from rabbit brain reagent. The high sensitivity shows a wide range: 8–220 seconds. We know the method linearity in this equipment is 8,0–320 seconds, and the percentage activity (that we still report) is “crazy” […]

Anticoagulant Therapy

How Rapidly Does INR Decrease?

Here is a question that came to me from the American Society for Clinical Laboratory Science Consumer Web Forum: How quickly will an elevated international normalized ratio (INR, PT/INR) decrease/time? I appreciate the answer may be “it depends,” but for patients on warfarin and with an elevated INR (for example 4.0 in a patient with and INR […]

Anticoagulant Therapy

Dabigatran Calibrators?

From Crystal Azevedo: I am currently evaluating the ECA-T kit to monitor dabigatran therapy. Are you aware of any labs/companies that have a set of validation plasmas? Sorry, Crystal, but no one is currently distributing dabigatran calibrators or controls, including the product developers at Diagnostica Stago, who have developed the research use only ecarin clotting assay (ECA) for […]

Anticoagulant Therapy

A POC DTI Monitor

At the ASCLS/AACC meeting in July I had the opportunity to chat with Tonya Kiziah, MT (ASCP), Helena Laboratories, about Helena’s new hand-held Abrazo instrument, currently research use only, which offers a new point-of-care (POC) direct thrombin inhibitor (DTI) assay, DTM. DTM is a dry chemistry modification of the Ecarin clotting time that employs paramagnetic iron oxide particle technology, […]

Anticoagulant Therapy

Establishing PTT Rx Range

From “Kkehoe“: Recognizing that the preferred method for establishing a partial thromboplastin time (PTT) therapeutic range for unfractionated heparin (UFH) is plotting the PTT against the anti-Xa, is there an alternative for labs that don’t perform anti-Xa testing? Are you aware of any commercial kits that can be purchased and used? We currently purchase a […]

Anticoagulant Therapy

Monitoring Heparin with the Anti-Xa assay

From Crystal Azavedo: Hi George, Are you aware of any observation or randomized controlled trial data that compares bleeding and thrombosis risk in patients receiving unfractionated heparin monitored with the activated partial thromboplastin time (aPTT, PTT) compared to monitoring with anti-Xa? In other words, are there clinical outcome data that suggest monitoring with anti-Xa improves patient outcomes? Thanks!! […]

Anticoagulant Therapy

PT Reagents

From Donna Lawler, University of Wisconsin: George, I have been reading with interest the ongoing discussion of PTT reagent selection and enjoyed the corresponding article you cited. I was wondering if you have any similar literature references concerning protime/INR reagents. We use a thromboplastin that has a low ISI (close to 1.0) and good factor sensitivities […]

Anticoagulant Therapy

Case: INR 2.2 but VII and IX are Normal

Here is a puzzler from Pam Owens at Tricore Reference Laboratories in Albuquerque. Hi George, we recently encountered a patient on warfarin (confirmed by clinician) whose international normalized ratio (INR) is 2.22, protein C and S are in the 30–40% range, but her factors VII and IX are “slam” normal. Have you ever encountered this? What could cause it? […]

Anticoagulant Therapy

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

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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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