PT Stability for Open Specimens

A new specimen question from Pam Owens, TriCore Laboratories: Hi George, this is a question with two parts. Given that a PT is stable for 24 hrs in the original tube with the top on (never removed)… 1. How long is the sample good once the top has come off? 2. If the plasma has been removed, […]

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Specimen Management

Mar 14 2012

george

Freeze-thaw Platelets and Growth Factors

From “abi:” We freeze-thaw platelets and aliquot them in 50 mL tubes stored at –80°C. After this we process 2–3 rounds of freeze thaw cycles before using these platelets in MSC cultures. 1. My question is, can we process this 2–3 rounds of freeze thaw cycle in advance, say a month prior to use, for […]

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Platelet Function Testing

Mar 14 2012

george

Does Elevated HCT Affect PT/INR?

Hello Mr. Fritsma, I am a pharmacy student working in an internal medicine clinic where we manage patients on warfarin. We had a question come in about how an elevated hemoglobin and hematocrit, HGB/HCT can affect INR levels as the lab is stating that as long as this patient’s hemoglobin is elevated, her INR results […]

Specimen Management

More on Look-Back for Positive APAs

Here is some in depth feedback from “Guest Blogger” Dr. Emmanual Favaloro on the subject of lupus anticoagulant chronicity raised by Pam Owens of TriCore Laboratories, Inc in a Feb 29 post. I sent the highlighted questions to Dr. F on Feb 27: When an LA/APA is defined as “chronic,” does it wax and wane? Not normally according to my understanding, […]

Lupus Anticoagulant

Anti-Xa Assay With LA Present?

Dear George, I have a lupus anticoagulant (LA) positive patient with recurrent pregnancy loss. She is on low molecular weight heparin (LMWH) with a request for an anti-Xa assay. Will LA positive whether it is interference by LMWH? What is your opinion? Hello, Vilas, the chromogenic anti-Xa heparin assay provides an accurate measure of unfractionated […]

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Anticoagulant Therapy

Feb 29 2012

george

Look-back for Positive APAs?

From Pam Owens at TriCore Reference Laboratories in Albuquerque: We are wondering if other labs research their patients’ positive antiphospholipid antibodies (APA) such as the lupus-like inhibitor (LLI, lupus anticoagulant, LA), anti-cardiolipin antibody (ACL) and β-2-glycoprotein 1 (β2GP1)) results to differentiate between persistent and new diagnoses. If so, how far back do they look for a positive? For example, if […]

Lupus Anticoagulant

DIC: Marker Recovery Time in Therapy

From “Siddhartha,” In disseminated intravascular coagulopathy (DIC) patients, what is the minimum time for the coagulation parameters D-dimer, fibrin degradation products (FDP) and fibrinogen to return to normal levels post frozen plasma (FFP) transfusion? Is it really worthwhile to do these tests in a suspected case of DIC who has already received FFP? Thanks, Siddhartha. […]

Fibrinolysis

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 […]

Mixing Studies

More on Clopidogrel Efficacy

This is a February 18, 2014 follow-up from the individual whom I responded to in a January 30 post entitled Clopidogrel Efficacy. I had collaborated with Prof. Bernadette Rodak of Indiana University on the original email to the questioner. Here is the comment (with identification removed): “I would like to thank you and Prof. Rodak for your response […]

Antiplatelet Therapy

More on PTT Specimen Storage Time

On November 1 I replied to a question from Joe Lamb, Columbus, GA about room temperature storage of specimens for partial thromboplastin time (PTT) assays that are sent to reference laboratories. Joe was concerned that his reference lab claimed PTT results were valid on specimens less than 24 hours old, whereas the CLSI Guideline H21-A5 sets […]

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Anticoagulant Therapy

All Posts

PT Stability for Open Specimens

Freeze-thaw Platelets and Growth Factors

Does Elevated HCT Affect PT/INR?

More on Look-Back for Positive APAs

Anti-Xa Assay With LA Present?

Look-back for Positive APAs?

DIC: Marker Recovery Time in Therapy

PTT Mix Prolonged Beyond Patient PTT

More on Clopidogrel Efficacy

More on PTT Specimen Storage Time

George Fritsma MS MLS

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