Mixing Studies

What Result Triggers a PTT Mix?

From Heather DeVries, Indiana University Health, “I answered the current Quick Question saying that we use another decision limit for doing a PTT mixing study. We require that the PTT be >3.0 seconds prolonged beyond the upper limit of our reference range, which is is 38.0 seconds. Thank you, Heather, there seems to be great […]

PTT Mixing Studies

From Alan Neal, Pathlab, New Zealand: We don’t reflex mixing studies unless clinically directed as they need a responsible clinician to discuss with haematologists. I strongly believe mixing studies can be misleading and numerous studies have identified lupus-like anticoagulants (LLACs, LACs) that correct with APTT mix study; approx. 40% abnormal APTTs do not have an […]

Mixing Studies Presentation

George provides a talk, Improving Acute Care with Coagulation Mixing Studies on Thursday, August 13 at the Kaiser Permanente Regional Reference Laboratories in North Hollywood, California, and Friday, August 14 at the Cedars Sinai Medical Center in Los Angeles. Please click the title above or Slide Deck if you would like to see the slides […]

Mixing Study Correction Survey

Here are the results of our July, 2015 mixing study correction Quick Question survey: When performing PTT mixing studies using normal control plasma (NP), what criterion do you use to define correction? A. Mix results within 10% of NP result—60 votes, 32% B. Mix results within 5 seconds of NP result—20 votes, 11% C. Mix […]

Mixing Study Correction Survey

Judy Miller reports, “Hi George, we currently use the Rosner Index, and consider an Index of >15 to indicate possible inhibitor.”

Mixing Studies with a Saline Mix

Dr. Ali Sadighi-Khomami, Precision bioLogic Inc, provided this paragraph from the Esoterix Coagulation handbook about the suggested saline phase mixing study.

Mixing Studies and Factor Assays

George is attending the International Society for Laboratory Hematology in Chicago, where he was presented a follow-up mixing studies question that was provoked by excellent discussions led by Drs. Mary Robinson and Dorothy Adcock of Esoterix Coagulation. The questioner performs a 1:1 mixing study using NP, and if it corrects, follows up with a mixing […]

PT and PTT Mixing Studies: Saline PNP Dilution

This post is reprised from 2013: From Courtney Jackson at Oschner in Louisiana: We use a commercial pooled normal platelet-free plasma (PNP) for our prothrombin time (PT) and partial thromboplastin time (PTT) mixing studies. When we mix it with saline for our controls, we don’t get a normal PTT until the ratio is 4 plasma to 1 saline. We […]

Mixing Studies with Controls

Thanks to all who attended our free webinar, Improving Acute Care with Coagulation Mixing Studies, Wednesday, May 13, sponsored by Precision BioLogic Inc. You can see and hear an archived copy of the entire webinar by registering on the Precision BioLogic web site by June 12. The webinar was hosted by CACMLE. There was an […]

Prekallikrein Deficiency

From Tracy Dixon, Western Australia Department of Health. Hi George, We have a case currently of an elderly man with metastatic melanoma and liver involvment who is giving us a consistently long APTT (PTT) with a silica reagent, often >200 seconds. Prolonged incubation with the silica reagent has shortened this to around 60 seconds. The […]

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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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