Mixing Studies

Combined IX and XII Deficiency?

From Dr. Jeanine Walenga, Loyola University Medical Center: George, what could be the reason(s) for a 30 yo female patient having multiple mild factor deficiencies of FIX (64%) and FXII (51%)? The activated partial thromboplastin time (APTT, PTT) was slightly prolonged but corrected with a mixing study. FVIII and FXI were normal. Patient does not have LA […]

What is an LDT?

From Kelly Townsend, Tri-core Reference Laboratories, Albuquerque. Looking for opinions on what constitutes a “Laboratory Developed Test” in Coag. Obviously if the reagent kit is not FDA-cleared, it will be an LDT, but what about factor assays, etc where there is no real kit. What if you are using a kit with a different calibrator or control […]

Uncontrolled Nosebleed

From Gabor Varadi, MD, Albert Einstein Cancer Center: Dear George, I would like to discuss with you a nose bleeding case. The patient is a 55 yo female with history of hepatitis C-induced chronic liver disease, alcohol and cocaine abuse who came to us with left nostril bleeding following finger trauma (nose picking). She does not […]

Mixing Studies on Minimally Prolonged PTs and PTTs

I pose this question to see what others are doing in this scenario and what literature there is to support your practice. We commonly get mixing study requests in which the PT or PTT are just minimally out of our normal range, such as 0.1 seconds outside for PT. Is this 0.1 second enough to […]

Quick Question: PTT Mixing Studies

The results of our January-February 2014 Quick Question: Does your laboratory perform follow-up partial thromboplastin time (PTT) mixing studies 24/7? a. No, only during the day shift, 46 (52%) b. Yes, all day and all night, 30 (34%) c. Not at all, we sent them out, 13, (14%) Total votes: 89 Thanks for the response, […]

Yet More on the PT Mix

From Ali Sadeghi-Khomami: Hi George, I read Dave McGlasson’s paper with great interest. In brief, his case had the following results: PT 60s PT mix 57s PTT >100s PTT mix 87s PTT 2 h 37°C incubation >200s Platelet neutralization (PNP) Positive Kaolin clotting time (KCT) >200s DRVVT screen Positive DRVVT confirm Positive The article didn’t mention anything about a […]

More on Incubated PT Mixing Studies

Yesterday, January 21, 2014, I posted “

Incubated PT Mixing Studies?

From Lori Pinelli, Glens Falls Hospital: Hello George. Our current prothrombin time (PT) mixing time procedure only includes running the initial 1:1 mix along with the patient and the normal pooled plasma (NPP). Twice in the past year, I have been asked to perform an incubated PT mix in addition to the initial analysis. Both patients had […]

More on Mixing Studies and Incubated Control

From Kathleen Tobertga: Hello, We are having problems between sites with the results of our 2 hour normal pooled plasma (NPP) control (unmixed) for our mixing studies. Our site (the main lab) is getting an increased value for the PTT around 40 s, which we have researched and seems to be elevated due to heat labile […]

Mixing Studies: Incubate Control Plasma?

From Louise Pleiss, MT (ASCP), Southcoast Medical Group: We recently changed our mixing study procedure to include rerunning of the normal pooled plasma (NPP) after a 2 hour incubation as one of our system controls, but we are having a difference of opinion about what should happen to the NPP. One site says that the partial thromboplastin […]

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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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