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 […]

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Lupus Anticoagulant

Oct 20 2012

george

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 […]

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

No Need for Prolonged LA Incubation

From Thomas Exner, Owner, HAEMATEX RESEARCH, Sydney, Australia: Hi George, I read your response to a question about lupus anticoagulant (LA) mixing tests in a handout at the SSC meeting in Liverpool recently. I’m a little disappointed that you still recommend prolonged incubation times for these. Most recommendations now are that LA mixes should be tested immediately […]

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Lupus Anticoagulant

Lupus Anticoagulant

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

Prolonged Mixing Study in Dialysis

Mix Corrects with NP, But not with Deficient Plasmas

No Need for Prolonged LA Incubation

George Fritsma MS MLS

Cheat Sheets from George

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