Mixing Studies After Fonda

Hi George, We have a question about performing mixing studies following fondaparinux or enoxaparin administration. How long do you recommend waiting (# half lifes) to perform mixing studies after these medications are administered? Thanks, Carla Purvis,Parkview Regional Medical Center, Fort Wayne, IN. Hi, Carla, and thank you for the question. Enoxaparin has a 4-hour half-life and […]

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Anticoagulant Therapy

Oct 25 2013

george

Anti-PF4/Protamine HIT

Hans Zwerger, Produktspezialist at CoaChrom Diagnostica, Vienna, Austria introduced me to an important clinical issue, anti-platelet factor 4 (PF4)/protamine antibodies that are implicated in heparin-induced thrombocytopenia with thrombosis (HIT). As you know, cardiologists employ high doses of standard unfractionated heparin during coronary artery bypass graft surgery, which anesthetists and anesthesiologists measure using the activated clotting time […]

Thrombophilia

Rapid HIT Assays

Informal discussions with Ginger Weeden and Lucinda Lojka from Bio-Rad, Incmade me curious about rapid assays for the antibody that causes heparin-induced thrombocytopenia with thrombosis (HIT), anti-heparin/PF4. In North America we typically screen with one of three enzyme immunoassay (EIA) methods, from GTI Diagnostics Inc., Waukesha, WI, USA, PF4 Enhanced®: GTI PF4 Enhanced Package Insert; Hyphen Bio-med, Neuville-Sur-Oise, France, Zymutest HIA® Assay; or Diagnostica Stago, […]

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Anticoagulant Therapy

Oct 24 2013

george

Rivaroxaban Specimen Stability

From Soakimi Pouhila, Auckland District Health Board, New Zealand: Hi George, any ideas on the stability of rivaroxaban in citrate samples? Hello, Soakimi Pouhila, and thank you for your question, which sent me to PubMed to see if anything has been published on rivaroxaban stability. My search was fruitless, so I’m posting your question to attract comments […]

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Anticoagulant Therapy

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 and PTT

A message from Vilas Hiremath: Dear George, hello. Female 30 yrs underwent laparoscopy, started bleeding. Prothrombin time (PT) and partial thromboplastin time (APTT, PT) prolonged, both mixing study 1:1 corrected. Normal fibrinogen and thrombin time (TT). Factor X, VIII. II normal, factor V is 6.0%. Dilute Russell viper venom time (DRVVT) screen and confirm both prolonged, […]

Bleeding Disorders

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

Coag Tests for a Community Hospital

From Meg Harlin, Peninsula Regional Medical Center in Maryland: Our Laboratory will be bringing in new coagulation analyzers from Instrumentation Laboratories, Inc.; TOPS 300, in February, 2014. We currently perform prothrombin time and international normalized ratio (PT/ INR), partial thromboplastin time (APTT, PTT), fibrinogen, and D-dimer. A Few years ago we stopped doing bleeding times, mixing studies and […]

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Anticoagulant Therapy

Oct 9 2013

george

More About Oral Anticoagulants

Question from a colleague: My 92-YO dad has atrial fibrillation and is on warfarin. He is well controlled and since he is independent and drives, getting monitored is not a big deal…while the pavement is dry. However, I am worried that he will venture out when he should not during the winter when he has […]

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Anticoagulant Therapy

Oct 8 2013

george

More on INR 10.0

Thanks to Vadim Kostousov for his comments appended to the September 28, 2013 post, Accuracy of an INR of 10.0. Here are the guidelines from the latest edition of the ACCP guidelines Chest 2012 Exec Summary: 9.1 Vitamin K for Patients Taking VKAs With High INRs Without Bleeding (a) For patients taking VKAs with INRs between 4.5 and 10 […]

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Anticoagulant Therapy

All Posts

Mixing Studies After Fonda

Anti-PF4/Protamine HIT

Rapid HIT Assays

Rivaroxaban Specimen Stability

“Backwards” FVIII Dilutions

Prolonged PT and PTT

Prolonged PT, TT, and PTT

Coag Tests for a Community Hospital

More About Oral Anticoagulants

More on INR 10.0

George Fritsma MS MLS

Cheat Sheets from George

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