Coagulation Factors

Prolonged PT, TT, and PTT

From Ning Tang: Hi, George, I come from a clinical laboratory in China. We met a confusing case today and want to get your suggestion: A patient had a prolonged prothrombin time (PT, 20s), partial thromboplastin time (APTT, PTT, 52s) and thrombin time (TT, 127s). Fibrinogen activity is within reference interval (by both Clauss method and […]

Bleeding Disorders

Antibodies to Bovine Thrombin

From Manju Bala, St Christopher’s Hospital for Children. Need help with interpreting a coagulation dilemma. A child, 4 months old, post cardiac surgery, no meds, use of bovine thrombin during surgery with prolonged prothrombin time (PT), 29.9s; partial thromboplastin time (PTT, APTT),107.7s; and thrombin time (TT), 40.4s; no correction on mixing. FII, 25%; FV, 7%, increasing with […]

Coagulation Factors

Ferritin and Prolonged PT/PTT?

From Natalie Shorey, Stago, Inc. Regional Manager, Sydney, Australia: This clinical case & related question came from the scientists at St George Hospital, one of our teaching hospitals here in Sydney. It prompted some discussion when I put it to other scientists, withour coming to any conclusion so I thought I’d pose the question to you. A patient […]

Coagulation Factors

Prolonged PTT in FXII Deficiency

From Maria Grana, Baptist Health Center: Hello, we recently had a patient with very high partial thromboplastin time (aPTT, PTT) resu;ts, anywhere from 115 to >200 seconds. The mixing study indicated a factor deficiency. Factor assays performed (IX, XI) were within normal limits, FVIII was elevated (>200) and Factor XII was 48%. It did not appear […]

Coagulation Factors

Assaying for HMWK and PK

From Michele L. Drejka, Lead Technologist, Barnabas Health, Newark, NJ: Hi George, Sorry to be redundant, but I posted this in ‘Comments,’ however I actually need an answer to my question below, so I am repeating here: Regarding prolonged activation times-I’m getting frustrated. I had more success with playing with this 15 years ago! However, this is […]

Coagulation Factors

ELISA Vs. LIA VWF:Ag

From Jasmina Ahluwalia: Hi George, Is there any advantage of choosing an immunotubidimetric (latex immunoagglutination, LIA) assay over the enzyme-linked immunosorbent assay (ELISA) for von Willebrand factor antigen (VWF:Ag)? Hello, Jasmina, and thank you for waiting for this answer while we updated the Fritsma Factor site. The two methods have similar sensitivity, specificity, linearity, and coefficient […]

Bleeding Disorders

FVIII Linearity; LA Testing

From Mahnaz Sairi, Associate Director of Hematology, MBHN: Hi George: What is the highest limit we can report For FVIII? And how we determine this? Is it by clinical significance or by instrument linearity? Also, should we still do lupus anticoagulant (LA) testing if both the prothrombin time (PT) and partial thromboplastin time (PTT) are normal? […]

Coagulation Factors

Why Express Factors in Percent?

This is from Ann McConnell, East Carolina University, first posted on November 19: Why are factor activity assays reported in the range of 50%–150%? I am having a difficult time wrapping my mind around the concept that something can be more than 100% “active.” Thanks! Hello, Dr. McConnell, and thank you for your question. To be honest, […]

Coagulation Factors

Inflammatory Markers

Here is another cogent comment from a University of Medicine and Dentistry Graduate Student. I didn’t get permission to post the student’s name, will add it later in a comment if permission is granted. We got into a side “conversation” about inflammatory markers and their crosstalk with hemostasis. As you can see, we get into some […]

Coagulation Factors

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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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