Anticoagulant Therapy

Comparison of INR with FII, FVIII, and FX

From Dave McGlasson: George, Here is a potential answer for Kelly Townsend’s February 13 post, Factor II Assay in place of INR. Kelly is right. We did look at the chromogenic factor X and published that work a few years ago McGlasson DL, Romick BG, Rubal BL. Comparison of a chromogenic factor X assay with international normalized ratio […]

Anticoagulant Therapy

Factor II Assay in Place of INR?

From Kelly Townsend at TriCore Reference Laboratories: We have several patients in whom the INR does not appear to accurately assess their anticoagulation status. Since we do not have the chromogenic factor X assay on our menu, we’re interested in using the factor II activity assay based on a poster presented at THSNA meeting by the Univ of […]

Anticoagulant Therapy

More on PT Validation and AMR

Here’s an additional note confirming Denise Solieau’s February 12 discussion of PT validation and analytical measurable ranges (AMRs). Page 83 of the July 31, 2012 CAP survey references the value of AMRs in coagulation testing and includes this statement, “The new checklist requirements (meaning AMR) apply to hemostasis test methods that are calibrated and directly measure the concentration or […]

Anticoagulant Therapy

Validating the PT: AMR and CRR?

From Denise Soileau, Helena Laboratories: It is my understanding that calibration verification is not required for prothrombin time. Is AMR and CRR? If so how do you suggest this be accomplished? Hello, Denise, and thank you for your question. I’ve had some help from Larry Brace PhD, Edward Hospital, and Dave McGlasson MS, MLS, Wilford Hall USAF Hospital. It is true […]

Anticoagulant Therapy

Bleeding After CABG: Heparin?

Here is a puzzling case sent by Crystal Azevedo: Hi George! I have a question for you from one of my pathologists. 24 hours after an uneventful coronary bypass procedure a 51 kg patient developed acute hemorrhage. A post-protamine thromboelastogram (TEG) on the day of surgery was completely normal. At the time bleeding occurred, the patient […]

Anticoagulant Therapy

Reprise: What About PT Owren?

Reposted from November 28, 2011 from Robert Löfvenmark, MediRox AB, Nyköping, Sweden: Hello, I am from Sweden and I am curious on the international differences in use of PT. Two PT methods are predominantly used today: PT Quick, developed by Dr Armand Quick, 1935; and PT Owren, by Dr Paul Owren 1951. Most parts of the […]

Anticoagulant Therapy

PTT >180 seconds

From Renee Nutting: Is a PTT of >180 seconds always the result of heparin contamination or would such a result ever be medically desirable for a patient? Hello, Renee, and thank you for your question. A partial thromboplastin time (PTT) of >180 seconds, or one at the limit of instrument measurement, is likely an indication of […]

Anticoagulant Therapy

Reprise: Switching to Anti-Xa

Reviewing Sue Bergs‘ March 23, 2012 post asking, How Many Use the Anti-Xa?, I noticed the comment appended by “Istano” asking for data on switching from PTT to anti-Xa heparin assay for routine heparin monitoring. My answer was somewhat incomplete, so I thought I should connect this question with Marisa Marques, MD‘s June 20, 2012 question, Do You Use […]

Anticoagulant Therapy

Correction to December 6 Post

A note from my friend and colleague, John Landis, who retired from the Clinical Laboratory Science faculty at Ferris State University in Big Rapids, Michigan a few years ago: “I just read the new Cheat Sheet and saw the question from Scott Millerand your response. Scott is a graduate of my Ferris State program, but he works at St Mary’s of Saginaw not Grand Rapids. […]

Anticoagulant Therapy

Apixaban Cleared for Afib

After a lengthy delay, the US Food and Drug Administration (FDA) cleared apixaban (Eliquis®, Bristol-Myers Squibb/Pfizer) for prevention of stroke in non-valvular atrial fibrillation on 12.28.12. Apixaban is an oral direct anti-Xa anticoagulant and joins rivaroxaban and dabigatran (a direct thrombin inhibitor) as the third new oral anticoagulant cleared since 2009. Details appear in TheHeart.org.

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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