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Quick Question Summary: Mixing Studies

Here are the results of our June QQ on Mixing Studies: When performing a partial thromboplastin time (PTT) mixing study using reagent pooled normal plasma (PNP), what do you use as your correction/non-correction limit? a. Mixture PTT is within 10% of the PNP PTT result: 9 (14%) b. Mixture PTT is within 5 seconds of […]

Functional Protein C

I have this message from Theresa Nwagha, University of Nigeria Nsukka: I am performing a functional assay of protein C in pregnancy will need help with SOP. Not a routinely performed assay in my center. Hello, Dr. Nwagha, and thank you for your message. May I recommend you purchase thePrecision BioLogic Cryocheck Clot C test kit. The […]

Developing a Reference Interval

From D. Kaguni: I would like to know where I would find information on validation of a rare factor activity assay in which the test kit is quite expensive and performing the recommended 120 normal plasmas to create a reference range would be very expensive. I have inquired with CLSI and they do not have […]

Heparinase

Margaret Peters, MD at MHS Health asks: What coagulation tests may be run on samples previously treated with heparinase? Is any correction factor required for a quantitative assay? Are there any published guidelines on this topic? Thank you! Hello, Dr. Peters. Heparinase is manufactured by Ibex and distributed by Siemens Laboratory Diagnostics, Inc. as Hepzyme. It specifically digests […]

PTT Mixing Studies With Saline

Joe Lamb asked, “George, I’m working on mixing study procedures for my lab. I’ve read about a saline mix and I’m looking for a reference for the technique. I’m interested in a procedure and how to interpret the results. can you recommend something for me?” Hi, Joe. I apologize for being a little slow on […]

Coagulation Testing Volume

From Greg Fullerton at Affinity Biologicals, Inc. Hi George, I am new to the industry and enjoy reading your site. It gives me a lot of insight into the world of hemostasis. I have two coagulation market related questions for you and a top five list. Hope you can help me out. 1) In your […]

ISTH Lupus Anticoagulant Guidelines

From Kim Kinney at Clarian Health in Indianapolis: Hi George. It was good to see you at the Midwest Hemostasis Symposium this year. My question stems from one of the presentations. There was a presenter from Texas, I believe, who gave a talk on multiple miscarriages. He mentioned that he had been at the recent ISTH meeting […]

Antithrombin Affects the Anti-Xa Heparin Assay

Here is a question from my friend and colleague, Vicki Cardone at Children’s Hospital of Alabama, just down the street from UAB: I am having a hard time getting the concept behind finding a decreased anti-Xa level when you have decreased antithrombin (AT, antithrombin III, AT III). What part of the patient’s heparin is the […]

Mixing Studies

Hello George, I just completed the Quick Question concerning PTT mixing studies. Our PTT mixing study consists of two parts, a control of NPP and factor VIII deficient plasma tested immediately upon preparation and after 60 minutes incubation at 37 degrees. The patient is also mixed 50/50 with NPP and tested immediately upon preparation and […]

A New NovoSeven?

Here is an interesting note from M. Thabet: “Could you please forward the brand name and prescribing information for the new Russian version of recombinant factor VIIa (rFVIIa) similar to NovoSeven?” Thank you for your question. NovoSeven goes off-patent in the United States in 2011, and Novo Nordisk is developing both a fast-acting analogue and a prolonged […]

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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.

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