Confusing Coag Test Names

On October 16, 2013 George spoke on the subject, “Clumsy Coagulation Communication, Let’s Blame the Lab” in Seattle, Washington. One issue we discussed was confusing coagulation test names, and we talked about the kinds of erroneous orders that are generated. Here is a follow-up to the presentation, a brief list of confusing names with an explanation for each. […]

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Coagulation Factors

Oct 19 2013

george

“Backwards” FVIII Dilutions

From Kim Kinney, Indiana University Health, Hi George! We have a severe hemophiliac with an 8BU inhibitor receiving ReFacto. Factor assays are high, but dilutions dilute backward! 367, 238, then 183, then 167 causing a CV flag. We have seen this before, but have never heard an explanation for the “backward” dilution affect. Can you shed light? […]

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, […]

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Coagulation Factors

Coagulation Factors

Confusing Coag Test Names

“Backwards” FVIII Dilutions

Prolonged PT, TT, and PTT

Antibodies to Bovine Thrombin

Ferritin and Prolonged PT/PTT?

Prolonged PTT in FXII Deficiency

Assaying for HMWK and PK

ELISA Vs. LIA VWF:Ag

FVIII Linearity; LA Testing

Why Express Factors in Percent?

George Fritsma MS MLS

Cheat Sheets from George

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