LA Testing When PTT is Normal?

Hello Geo, I have a question about lupus anticoagulant (LA) testing. Before I go off and tell people wrong I thought I would run this by you. Situation is, we have physicans who want to run antiphospholipid syndrome panels on patients who have a history of having a clot (one time usually). The activated partial […]

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Lupus Anticoagulant

Jan 11 2013

george

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

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

The Difference Between SLE and LA

From David Summers: I have a question regarding the following lab results and all clinical symptoms which seem to represent systemic lupus erythematosus (SLE): PTT LA 52 seconds, reference limit 40 seconds DRVVT screen 44 seconds, reference limit 42 sec Antithrombin antigen 39 mg/dL, reference interval 18–33 mg/dL Protein C activity 13%, reference interval 70–180% There is a […]

Lupus Anticoagulant

Do APAs Affect the PT?

From Scott Miller, St. Mary’s of Michigan Medical Center. Is there any consensus on whether anti-phospholipid antibodies (APAs) like lupus anticoagulant (LA) have any effect on prothrombin times and international normalized ratios (PT/INRs)? We have a patient who has been tested positive in the past for LA, and her INRs consistently run a bit higher in the […]

Lupus Anticoagulant

Do APAs Affect the PT?

From Scott Miller, St. Mary’s of Michigan Medical Center. Is there any consensus on whether anti-phospholipid antibodies (APAs) like lupus anticoagulant (LA) have any effect on prothrombin times and international normalized ratios (PT/INRs)? We have a patient who has been tested positive in the past for LA, and her INRs consistently run a bit higher in the […]

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

Tissue Thromboplastin Inhibition Test

Here is a question that appeared on the Clinical Laboratory Science (CLS) Educators’ list: “We are trying to figure out the principle, procedure for the tissue thromboplastin inhibition (TTI) test. We are aware that it seemingly is no longer performed, but feel there is a good chance that the ASCP could potentially ask questions about […]

Lupus Anticoagulant

Factor Assays: How to Define Parallel Results

From Maria Franco, Orlando Health: Hi, George, when running factor assays (1:10, 1:20, etc), is the agreement between results to r/o inhibitory activity all calculated from the original result (1:10)? Not sure what the most common or recommended practice is. I have heard to find the mean of all results and then try to calculate the deviation. […]

Factor Assays

PTT Reagent LA Sensitivity in Mixing Studies

Hello George, My name is Marcelo Gonçalves, clinical pathologist from Hematology Department of Hermes Pardini Laboratory, Brazil. I would like to ask what kind of activated partial thromboplastin time (APTT, PTT) reagents should be used in APTT mixing studies (high or low responsiveness to LA)? Thank you for your attention. Dr. Marcelo Luide Pereira Gonçalves Thank […]

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Lupus Anticoagulant

Lupus Anticoagulant

LA Testing When PTT is Normal?

Rivaroxaban and LA?

FVIII Linearity; LA Testing

The Difference Between SLE and LA

Do APAs Affect the PT?

Do APAs Affect the PT?

Incubated PTT Mix: What Constitutes Correction?

Tissue Thromboplastin Inhibition Test

Factor Assays: How to Define Parallel Results

PTT Reagent LA Sensitivity in Mixing Studies

George Fritsma MS MLS

Cheat Sheets from George

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