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 […]

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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

PEG-ylated Drugs and Clotting Assays

From Vanessa Chan, Sick Kids Hospital in Toronto: Hi George, Do you have any information on how PEG-ylated drugs (PEG-ylated to increase the half life of the drugs) may affect clotting assays? Thanks! Vanessa. Hi, Vanessa, While I have heard that polyethylene glycol (PEG) in drugs can affect the phospholipid structures in prothrombin time (PT) thromboplastin reagent and […]

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Anticoagulant Therapy

Sep 25 2012

george

Elagic Acid-based PTT Reagent

From Kelly Rose at Novartis: Hi George, I work in a research lab and we are interested in comparing different partial thromboplastin time (PTT) reagents on our Stago Sta-R. Currently we use the silica-based (STA PTT-Automate) and kaolin-based STA C. K. Prest. We would like to try ellagic acid. Have you had any experience with this reagent? and […]

Screening 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

Validating High POC INR Results

Our April 24, 2012 post (and Quick Question), POC: When to Validate a High INR has attracted a provocative comment from Alan Neal of New Zealand. I’ve added this link so the comment does not get buried and to attract additional discussion from our participants.

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Anticoagulant Therapy

Sep 12 2012

george

Validating High POC INR Results

Our April 24, 2012 post (and Quick Question), POC: When to Validate a High INR has attracted a provocative comment from Alan Neal of New Zealand. I’ve added this link so the comment does not get buried and to attract additional discussion from our participants.

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Anticoagulant Therapy

Aug 25 2012

george

How Rapidly Does INR Decrease?

Here is a question that came to me from the American Society for Clinical Laboratory Science Consumer Web Forum: How quickly will an elevated international normalized ratio (INR, PT/INR) decrease/time? I appreciate the answer may be “it depends,” but for patients on warfarin and with an elevated INR (for example 4.0 in a patient with and INR […]

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Anticoagulant Therapy

Jul 29 2012

george

PT Reagents

From Donna Lawler, University of Wisconsin: George, I have been reading with interest the ongoing discussion of PTT reagent selection and enjoyed the corresponding article you cited. I was wondering if you have any similar literature references concerning protime/INR reagents. We use a thromboplastin that has a low ISI (close to 1.0) and good factor sensitivities […]

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Anticoagulant Therapy

Jul 14 2012

george

APCR Screening: Everyone?

Our recent series of discussions and comments on the efficacy of D-dimer results in superficial thrombophlebitis for factor V Leiden (FVL) mutation patients has pointed us to a thoughtful discussion of the value of screening unselected populations for activated protein C resistance (APCR), the condition that correlates closely with FVL. Dr. Emmanual Favaloro’s current article; Favaloro EJ, McDonald D. Futility […]

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Screening Assays

Screening Assays

Do APAs Affect the PT?

Do APAs Affect the PT?

PEG-ylated Drugs and Clotting Assays

Elagic Acid-based PTT Reagent

PTT Reagent LA Sensitivity in Mixing Studies

Validating High POC INR Results

Validating High POC INR Results

How Rapidly Does INR Decrease?

PT Reagents

APCR Screening: Everyone?

George Fritsma MS MLS

Cheat Sheets from George

Questions or Comments?

Quick Question