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Interpreting a prolonged PT and PTT

Hi George, I am a MLT and I am currently working on my MT. I have a few questions about mixing studies. I have listened to several of your modules on your website but I am still having trouble with understanding factor deficiencies in certain scenarios. If a patient has a prolonged PT and PTT […]

Determining Reference Intervals

I’ve enjoyed an interesting exchange with an engineer who contacted the American Society for Clinical Laboratory Science Consumer Forum. She was concerned that her blood specimen, which had been sent to two laboratories for complete blood counts, had generated the same hemoglobin result from each, however one reported the value as normal and the other as elevated. […]

Quick Reference

George, I was wondering if you could recommend a “quick” reference guide that provides a comprehensive yet easily understandable overview of hemostasis (I know this may be an oxymoron). Our off shifts are sometimes questioned by clinicians (mainly residents) about interpretations of “special” coagulation tests (lupus anticoagulant, APC testing, proteins C and S, etc). While […]

HELLP Syndrome

Here is a question about HELLP from a colleague with heterozygous factor V Leiden mutation. George: If you have not heard I had my baby, a healthy boy. I had HELLP syndrome/preeclampsia. Do you know of any studies that may link factor V Leiden to HELLP? Just curious. A quick PubMed search turned up approximately […]

Platelet Clumping in Sodium Citrate and Plateletpheresis

An interesting question from Mary Coleman at the University of North Dakota: A female student reported to student health with a severe headache. She had a complete blood count performed using a standard EDTA tube and she had a low platelet and elevated lymphocyte count. The laboratory scientist also prepared a direct blood film from […]

Rivaroxaban Vote

The US Food and Drug Administration’s (FDA) Cardiovascular and Renal Drugs Advisory Committee recommended approval of Rivaroxaban (Xarelto) oral anti-Xa antithrombotic for prophylaxis of deep vein thrombosis (DVT) and pulmonary embolism (PE) in patients undergoing hip replacement or knee replacement surgery. The FDA has until May 28 to vote full approval. See Medical News Today for more […]

Adsorbed plasma and aged serum

Dear George, I am finding reference to the use of aged serum or adsorbed plasma in mixing study board review questions, yet no information in the current texts. Are those out of date procedures? Thank you, Tania Puro Hi, Ms. Puro. You are correct, the substitution assays are no longer used and are not likely […]

Antiplatelet Resistance Testing and Ristocetin

Here’s a new message from Kim Kinney at Clarian in Indianapolis: Hi George, I have a question in regards to platelet aggregation and the effects of plavix and aspirin. We have had several patients where just the AA, ADP and collagen are abnormal but we have had a few where the ristocetin is also abnormal! […]

Lupus Anticoagulant Targets Factor XI: Barranco Reply

This is an interesting issue that we have encountered in our laboratory too. We have used a Kaolin based reagent with good success in some cases. I will be giving an oral presentation at the upcoming Mayo Testing Quality Conference about our experience using an alternative activating reagent to perform factor assays in the presence […]

Factor XII Deficiency and Thrombosis

Janice Richardson asks, “Why does a low factor XII cause clotting?” Factor XII was described in 1955 by Ratnoff and Colopy who recognized its deficiency in an American male, John Hageman. Factor XII deficiency causes a markedly prolonged activated partial thromboplastin time (APTT, PTT) but paradoxically does not associate with bleeding. Most of us know […]

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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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