Mixing Studies

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 […]

Anticoagulant Therapy

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

Positive DRVVT when Mixing Study Corrects

From Aliaa Amer: Hi George, we are using Actin FSL for our routine activated partial thromboplastin time (APTT, PTT). Whenever we get a prolonged APTT that is >5 s above the upper limit of the norm range we do mixing studies, both immediate and 2 h incubation using 1:1 and 4:1 mix, the latter to detect […]

Lupus Anticoagulant

More on “Unexpected DRVVT Results”

Here is a message about the dilute Russell viper venom time assay (DRVVT) for lupus anticoagulant (LA) from international expert Thomas Exner, HAEMATEX, Sydney, Australia: It was a pleasure to meet you at the International Society on Thrombosis and Haemostasis (ISTH) meeting recently. I would like to respond an interesting question raised on July 16, 2013 in your Fritsma Factor website. […]

Lupus Anticoagulant

Lupus Anticoagulant Panel

From Don Wahl, Sanford Health: What are the recommended tests to include in a lupus anticoagulant/antiphospholipid antibody (LA/APL) panel? Is there an antiphospholipid group that gives recommendations? Thank you, Don. Hello, Don, and thank you for your question. The group you need is provided in the title of this reference, and the reference provides the assays that […]

PTT Mix Prolonged Beyond Patient PTT

From “Danagah” (originally posted February 23, 2012): Hi, George, have you seen the situation when, in the 1:1 immediate mix of a partial thromboplastin time (PTT) mixing study, the PTT is longer than the patient’s initial PTT? The patient does not appear to be on heparin (data to follow): Patient PTT: 39.0 sec Normal pool: 30.9 sec 1:1 […]

Rivaroxaban and LA?

There are three helpful comments appended to our December 5, 2012 Delta Checks for PT, PTT, Fg, and D-dimer post. One came from “goblue,” whom I surmise is aUniversity of Michigan Wolverines fan (sorry about that South Carolina game): “While administering Xarelto (rivaroxaban), will this give a false positive result on lupus anticoagulant (LA) tests?” Yes, as rivaroxaban […]

Lupus Anticoagulant

Incubated PTT Mix: What Constitutes Correction?

From Sylvia Bunting, Children’s Healthcare of Atlanta: We do an immediate and incubated mixing study. For deciding on whether there is a time-dependent inhibitor, what criteria do you use to decide that the PTT was prolonged after incubation? Any prolongation beyond the immediate mix PTT? Thanks. Hi, Sylvia, and thank you for your question. If the PTT […]

Lupus Anticoagulant

Prolonged Mixing Study in Dialysis

From “Balasubm” at Einstein Healthcare in Philadelphia: Hi George, I have a 74 year old female renal dialysis patient who is asymptomatic with prolonged prothrombin time (PT) of 38 seconds and activated partial thromboplastin time (APTT, PTT) of 116 seconds, with a normal thrombin time. Mixing performed immediately reveals PT of 30.3 seconds (N 9.5-13.5) and […]

Lupus Anticoagulant

Mix Corrects with NP, But not with Deficient Plasmas

From “Japgi,” I have a 6 year old boy, well till a month back, when he had a post-traumatic gum bleed. The bleed was stopped after about half an hour, but a small ooze restarted and stayed for 3 days. His prothrombin time (PT) is 14 seconds (RI 11–16), activated partial thromboplastin time (APTT, PTT) […]

Lupus Anticoagulant

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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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