Validation

Differential Discussions: VWD Type 1 and RCo.

Thanks to Malissa Norfolk and David Calder for our Differential Discussions conversation describing the time-honored Ristocetin Cofactor (VWF:RCo) test for von Willebrand factor activity, a member of the von Willebrand disease diagnostic assay, released January 1, 2025 on YouTube. Please click the link and join the discussion.

Bleeding Disorders

Hot Topics in Hemostasis: Nomenclature Standardization

Frequent contributor David L. McGlasson is featured in the Differential Discussions series hosted by Assistant Professor David Cabral, MBA, MLS(ASCP)cm, SH(ASCP)cm of the University of Massachusetts Dartmouth, and Assistant Professor Malissa Norfolk, MBA, MLS(ASCP)cm, SH(ASCP)cm, of the University of Maine-Augusta faculty. Click here to meet Malissa and David, and to hear Mr. McGlasson’s discussion of […]

Coagulation Factors

VKA Monitoring in Hepatic Insufficiency

Here is a challenging case from Hrvoje Melinšćak sent 5-30-24: Dear George, In hepatic insufficiency there is often a prolonged basal protime, how to ensure therapeutic values of warfarin when the INR is already elevated? This is of particular concern in those with mechanical cardiac valves. Serum warfarin levels (spectrophotometry) are cumbersome and take days to […]

How to Measure Plasma Efanesoctocog Alfa [Altuviiio]

For those like me [Geo] who are just learning of it, efanesoctocog alfa (“EFA,” ALTUVIIIO™), US FDA-approved in February of 2023 is Sanofi/Sodi’s extended half-life synthetic FVIII concentrate whose FVIII molecule is fused to a VWF fragment, thus extending the half-life to ~52 hours, requiring once-a-week infusions. Here is the FDA statement: Efanesoctocog alfa (ALTUVIIIOTM; […]

Bleeding Disorders

Hemostasis Quality Control Modules

Fritsma Factor is pleased to introduce our most recent audio PowerPoint modules, Hemostasis Quality Control Part 1 and Hemostasis Quality Control Part 2. These modules were produced by friend, colleague, and co-author Mayukh Sarkar, Ph.D MLS [ASCP] for the Rutgers University 2023 graduate course, Advanced Hemostasis CLS5124. Dr. Sarkar has a wealth of QC experience […]

More on CaCl2 Validation

We recommend you return to our February 4, 2024 entry that discusses CaCl2 validation. We’ve received additional comments including a comprehensive response from several expert CAP staff members.

April 2022 QQ: Measuring Heparin

Our April 2022 Quick Question reprises our May 16, 2012 post, “Who Uses the Hybrid Curve?” but adds a twist based on May JE, Siniard RD, Taylor LJ, Marques MB, Gangaraju R. From activated partial thromboplastin time to anti-factor Xa and back again; the evolution of monitoring unfractionated heparin. Am J Clin Pathol 2022;157:321–7 HTTPS://DOI.ORG/10.1093/AJCP/AQAB135. […]

Anticoagulant Therapy

More on Geomean: Instrument Specific or System-Wide?

A recent comment [click] from Dr. Emmanuel Favaloro on our November 9 discussion of a system-wide geomean was posted 12/15/21.

Geomean: Additional Information

From Hillary Thurman: Here is some additional information, in response to Bob Gosselin’s 11-6-21 response: The RIs currently in use are the manufacturer’s suggested ranges. Each site collected screened normal samples and EP Evaluator was utilized to ensure the patient population did not fall outside this range. Each site (there are seven) currently has one […]

Geomean: Instrument Specific or System-Wide?

Hillary Thurman is looking for some insight, She writes, “We have recently standardized hemostasis instruments across our system. The rest of the system has been using a combined geometric mean for their PT reagent (same lot, same instruments), but my site has never been involved in this. In addition, they do not change the geomean […]

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