Mixing Studies

Mixing Studies While on Pradaxa?

From Sara Sneeden, Lee Memorial. Our hematologists are ordering mixing studies on patients who have been on Pradaxa® at home. These patients arrive at the hospital with VMax prothrombin time (PT) and activated partial thromboplastin time (PTT, APTT) and some time later the mixing study is ordered on a subsequent draw. Is there anything to be […]

Validating the Rosner Index

From “Maria:” Hello, I am looking into using the Rosner Index to assess mixing studies correction or not. Literature states that the Rosner Index must be validated with each new lot # of partial thromboplastin time (PTT) or prothrombin time (PT) reagent. Do we also need to validate each new lot of CaCl2? Also, what […]

Standard Mixing Study Calculation?

From “axnzak:” Is there a widely used (most current) calculation that is successful at interpreting inhibitor vs factor deficiency. Wanted to see what you would use to determine mixing study results, both prothrombin time (PT) and partial thromboplastin time (PTT), when comparing results to patient normal PT and PTT reference ranges. If not can you […]

How to Remove IgG

This question was posted on Wednesday, May 23 on Pat Letendre’s Medlab list and is reposted here with Linda Stang’s permission: We have a patient with lymphoma and an IgG peak (we think). The antibodies are interfering (and I mean really interfering) in the coags: INR >5.0 but has had clinical challenges with no bleeding. Is there any way to remove […]

Anticoagulant Therapy

More on Mixing Studies: Dr. Ortel

We’ve had three posts and several comments regarding lupus anticoagulant (LA) mixing studies since March. These are… March 18, 2012: Test for LA When Mixing Study Corrects? March 22, 2012: Mixing Study Results: Long PT and PTT April 3, 2012: More on LA Mixing Studies In these posts several experts held that it is necessary […]

Lupus Anticoagulant

Mixing Studies: Do You Incubate?

Here is a message from Ms. Khaldee Lindsey Davenport-Landry (Lindsey), a graduate student in this spring’s University of Medicine and Dentistry of New Jersey’s graduate course, CLSC 5124, Advanced Hemostasis. Lindsey is an experienced medical laboratory scientist; she asks about mixing studies: We do a rare mixing study at our hospital, and even more rare PTT mixing study. […]

More on LA Mixing Studies

I received this message from Dr. Rich Cambereri on March 8, and have been holding it pending additional data, but given our March 18, 2012 post from Vanessa Chan in Toronto, and subsequent responses from Herb Crown and Dr. Larry Brace, I’ve decided to use Dr. Cambereri to start a discussion about the use of mixing studies in the lupus anticoagulant (LA) profile: Hi […]

Lupus Anticoagulant

Mixing Study Result: Long PT & PTT

From “Begumra:” Deficient factor in case of prolonged PT and PTT result that corrected with the addition of normal pooled plasma. All other screening tests are normal. I think it is factor V. Can you suggest that it is right? Hello, and thank you for your question. Assuming the patient is not on heparin or […]

Test for LA When Mixing Study Corrects?

From Vanessa Chan, Sick Kids Hospital, Toronto: Hi George, What is your opinion on the algorithm of tests when testing for lupus anticoagulant? If the mixing tests are normal, should we continue with a confirmatory test? The recent BJH guidelines say, “Mixing tests are a criterion for LA and improve the specificity. However, they introduce a dilution […]

Lupus Anticoagulant

PTT Mix Prolonged Beyond Patient PTT

From “Danagah” (originally posted February 23, 2012): Hi, George, have you seen the situation when, in the 1:1 immediate mix of a partial thromboplastin time (PTT) mixing study, the PTT is longer than the patient’s initial PTT? The patient does not appear to be on heparin (data to follow): Patient PTT: 39.0 sec Normal pool: 30.9 sec 1:1 […]

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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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