Screening Assays

ACT Testing Time Interval

Here is a question from my friend and colleague Kathleen Finnegan, MS MT (ASCP )SH, Chair of the CLS program at Stony Brook University, New York. This question was posted to the ASCLS Consumer Web Forum through Lab Tests Online: “In the procedure room setting (cardiac catheterization or EP lab) what is the standard length of time to wait to […]

Anticoagulant Therapy

No More PT in Seconds?

From Dr. Larry Brace, Edward Hospital, Naperville, IL: I need an opinion. Here is my view on prothrombin time (PT) in seconds. We should no longer have to do a normal range for the PT in seconds. We know that the general consensus is that the international normalized ratio (INR) is considered normal to at least 1.2 […]

Anticoagulant Therapy

Shortened PTT

Let’s highlight Marianne Thawley’s question that appears in a comment on the March 8 post, Rapid INR Rise in Pneumonia, “What are some causes for decreased PTT results.” In my experience, only technical artifacts shorten the partial thromboplastin time (PTT) to less than the lower limit of the reference interval. Artifacts could include partial activation of the coagulation […]

Screening Assays

Rapid INR Rise in Pneumonia

From Michael Huang, MicroPoint Bio: An 80 yr old male on warfarin was admitted to A&E of a local hospital for the complaint of shortness of breath. Lab test results showed INR of 15 after his admission. Just 8 hours before, the POC instrument his doctor used to monitor his INR showed a reading of 2.6. The […]

Anticoagulant Therapy

High HCT and PT, PTT, and D-dimer

From Barbara Robinson, MT (ASCP), Children’s Hospital of New Orleans, If a sample is tested for D-dimer, prothrombin time (PT) and partial thromboplastin time (aPTT, PTT), and the anticoagulant in tube has not been adjusted for high hematocrit (HCT = 60.8%), what tests would be invalid, and how would results be affected? Hi, Barbara, and thank you […]

Screening Assays

Factor II Assay in Place of INR?

From Kelly Townsend at TriCore Reference Laboratories: We have several patients in whom the INR does not appear to accurately assess their anticoagulation status. Since we do not have the chromogenic factor X assay on our menu, we’re interested in using the factor II activity assay based on a poster presented at THSNA meeting by the Univ of […]

Anticoagulant Therapy

More on PT Validation and AMR

Here’s an additional note confirming Denise Solieau’s February 12 discussion of PT validation and analytical measurable ranges (AMRs). Page 83 of the July 31, 2012 CAP survey references the value of AMRs in coagulation testing and includes this statement, “The new checklist requirements (meaning AMR) apply to hemostasis test methods that are calibrated and directly measure the concentration or […]

Anticoagulant Therapy

Platelet Function Testing and the Bleeding Time

In 2009 Dave McGlasson and I published McGlasson DL, Fritsma GA, Whole blood platelet aggregometry and platelet function testing. Semin Thromb Hemost 2009;35:168–80. This article, the second-most cited in the 2009 Seminars in Thrombosis and Hemostasis, reminded me of our Quick Question about the Ivy bleeding time posted in early November, and subsequently lost when our site crashed […]

Bleeding Disorders

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 […]

Screening Assays

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

Load more

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.

Cheat Sheets from George

Quick Question