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Prolonged PT and PTT That Don’t Correct

George, I am trying to work on a hemostasis project for school and I do not have any experience at all in a hemostasis laboratory apart from running PT and PTTs. What if a patient has an abnormal PT and PTT that are not corrected by mixing study? My guess is because it didn’t correct, […]

Quick Question Summary: Specimen Freezing

Our specimen freezing question arose in response to an October 6 post from Anne-Marie Quinn, Janssen-Ortho, Canada. The responses had a degree of unanimity not often seen on Fritsma Factor! Here they are: How do you freeze coagulation assay plasma samples? 1. Place in a -20°C (household) freezer: 10 (20%) 2. Place in a -70ºC (laboratory) freezer: […]

PFP Versus PPP

From Robert Gosselin at UC-Davis in Sacramento: Hello GF, Just as a side note, in the lupus anticoagulant comment you indicated “…which is performed using PFP, plasma whose platelet count is less than 10,000/mcL.” One has to assume that the abbreviation PFP is for platelet-free plasma as opposed to platelet-poor plasma. The former, platelet free […]

False Positive Phospholipid Neutralization

G Pihan from Beth Israel Deaconess asks, “What is the incidence of false positive hexagonal phospholipid neutralization tests in the presence of a strong (400-800 BU) factor VIII inhibitor?” Great question! Hexagonal-phase phosphatidyl ethanolamine is the chemical formulation for the phospholipid neutralization reagent used in Diagnostica Stago’s Staclot-LA lupus anticoagulant (LA) confirmatory assay. Their hex-phase phospholipid is widely regarded as […]

Pre-op Plavix Test

From Dan Hood: What testing do you recommend for Plavix effect for patients preoperatively? We have neurosurgeons testing the morning of surgery and are looking for some options. Hi, Dan, thank you for your question. Plavix is a thienopyridine that suppresses platelet activation by blocking membrane ADP receptors. The reference method is platelet aggregometry using […]

Short APTT Sensitivity Survey for Physicians

Fritsma Factor recently posted a brief survey asking laboratory scientists to characterize the sensitivity of their “routine” activated partial thromboplastin time (APTT) assay for lupus anticoagulant (LAC). This is a three-question follow-up survey for physicians. To go direct to the survey, select APTT Sensitivity Survey. For further explanation, please continue reading. The activated partial thromboplastin time (APTT) assay […]

Apixiban Phase 3 Trial Halted

On 11/19/10, Pfizer and Bristol Myers Squibb discontinued the APPRAISE-2 phase 3 trial of Apixiban in high risk patients with acute coronary syndrome. Apixiban bleeding risks were not offset by its antithrombotic benefit in the high-risk patient population. Details are available from theheart.org. At least two trials appear to show that Apixiban, which is a direct […]

Mixing Studies and the Thrombin Time

This question arrived as a comment from “skierktc;” I have reproduced it as a post here: I am preparing to update our laboratory’s procedure for prothrombin time (protime, PT) and partial thromboplastin time (PTT) mixing studies and wonder if anyone screens additionally with the thrombin clotting time (TCT, TT) or the TT plus protamine sulfate […]

Mixing Studies Interpretation

A question about mixing studies from Stacy Askvig at the University of North DakotaMedical Center. Stacy’s question arrived via Lab Tests Online and the American Society for Clinical Laboratory Science Consumer Forum: I do only PTs and PTTs, and my references seem to give me conflicting interpretations. Our patient has a prolonged PTT and DRVV, both are shortened in mixing studies: […]

Anti-Xa and Lipemia

From “McDowekm:” We currently perform anti-Xa heparin testing on a hybrid curve using Stago’s Rotachrom reagent on our Stago Compact. If we have a specimen that is lipemic, it can falsely increase the anti-Xa result. Can these specimens be ultra-centrifuged to obtain a more accurate Anti-Xa result? Hello and thank you for your question. It […]

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George Fritsma is a medical laboratory scientist, educator, and author. George holds faculty appointments with Rutgers University and Michigan State University, and is a member of the International Society on Thrombosis and Hemostasis, American Association of Clinical Chemists, and American Society for Clinical Laboratory Science.

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