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Reference Intervals in Multiple Sites

George received a question from a colleague who is preparing to establish a PT reference interval (RI) for a series of laboratories, large and small that use coagulometers with a range of sophistication from a single manufacturer. All the labs will use a single PT reagent from the manufacturer who distributes the instruments. The key […]

Screening Assays

HCT >55% and Citrate Volume Adjustment

George, is there research available now that states a HCT >55% will not interfere with PT or PTT results? We struggle with the CAP requirement. We use a mechanical based method for PT and PTT within our organization. Hello, and thank you for your question. The current CLSI guideline, Adcock DM, Hoefner DM, Kottke-Marchant K, […]

Screening Assays

PTT Mixing Studies

From Alan Neal, Pathlab, New Zealand: We don’t reflex mixing studies unless clinically directed as they need a responsible clinician to discuss with haematologists. I strongly believe mixing studies can be misleading and numerous studies have identified lupus-like anticoagulants (LLACs, LACs) that correct with APTT mix study; approx. 40% abnormal APTTs do not have an […]

Effect of HCT on POC INR

George received this question from the ASCLS Consumer Web Forum via Bonnie Jo Taylor, MHS, MT(ASCP)SH. I have hemochromatosis, too much iron in my blood. I’ve also had blood clots in my lungs. I peroidically undergo phlebotomy treatments to lower iron count. Will this alter the results of my INR finger prick test results? Here […]

Anticoagulant Therapy

More on PFA-100 Specimens

In follow-up to our 11/11/15 Collecting PFA-100 Specimens post, I’ve received responses from Donna Castellone and Drs. Ali-Sadeghi-Khomami and Emmanual Favaloro: First from Ms. Castellone: Most important is that your reference range reflects how you draw the patients–21 gauge, butterfly, the patients should be the same. Constancy is most important! Next, this detailed information from […]

Platelet Function Testing

Collecting PFA-100 Specimens

Here is a stimulating question sent to Dennis Ernst, Center for Phlebotomy Education, from a participant in his Phlebotomy Supervisors’ Boot Camp: One of our physicians asks that we collect specimens for PFA-100 assays using an 18g needle. Our laboratory scientists support this requirement, indicating that lab protocol requires that we not use a needle […]

Platelet Function Testing

Factor XII Deficiency and the Intrinsic Pathway

Ellie Coggins, MLS(ASCP)CM, MSHA, writes, I have a coagulation question I’m hoping you can help me with. I am wondering why factor VII deficiency causes significant bleeding problems but factor XII deficiency does not. One source I found stated that this is because the extrinsic pathway is the primary pathway in vivo and that the […]

Coagulation Factors

Dabigatran Safety and Efficacy in Women

Here is an October 28, 2015 Heartwire article describing differences in dabigatran safety and efficacy between women and men.

Anticoagulant Therapy

Mayo Labs Conference in Scottsdale, Nov 18–20

Mayo Medical Laboratories hosts its annual conference, this year entitiled Clinical and Laboratory Update in Thrombosis and Anticoagulation at the FireSky Resort and Spa, Scottsdale, Arizona, Wednesday, November 18–Friday, November 20. Precision BioLogic Inc. is a major supporter of the Mayo Labs Conference, and this year, as in the past, will host a booth in […]

Vitamin K Deficiency and Skin Necrosis

Elaine Keohane, PhD, MLS, chair of the Department of Clinical Laboratory Sciences, Rutgers University passes along this question from a medical student. Factor VII and protein C have about the same half-life (~6 hrs). In early vitamin K deficiency, is there a period of hypercoagulability due to the low protein C activity (similar to initiation […]

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George Fritsma is a medical laboratory scientist, educator, and author. George is a member of the International Society on Thrombosis and Hemostasis, the International Society for Laboratory Hematology, and the American Society for Clinical Laboratory Science.

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