Why Are PT & PTT Normal in Dysfibrinogenemia?

From Tania Puro, first posted on November 14: Can you explain why the activated partial thromboplastin time (APTT, PTT) and the prothrombin time PT are normal in dysfibrinogenemia? Hello, and thank you for your question. Dysfibrinogenemia is a qualitative or functional fibrinogen deficiency associated with moderate to severe liver disease. The liver produces normal or even […]

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Screening Assays

Oct 23 2012

george

Does In Vivo Citrate Affect PT or PTT?

From Madan Verma: Hi George. I am wondering if there are any correlation studies about whether switching hemodialysis patients from heparin to 4% sodium citrate will affect the prothrombin time (PT) or partial thromboplastin time (PTT). Thank you. Hello, Madan Verma, and thank you for your patience. I found over 500 PubMed references, most of which […]

Screening Assays

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

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

Screening Assays

Why Are PT & PTT Normal in Dysfibrinogenemia?

Does In Vivo Citrate Affect PT or PTT?

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?

George Fritsma MS MLS

Cheat Sheets from George

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