Validation

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 […]

Hemostasis in Selected Populations

In Keohane EM, Otto CN, Walenga JM: Rodak’s Hematology; Clinical Principles and Applications, Sixth Edition, 2020, Dr. Linda Goossen provides a timely and clinically significant chapter, “Hematology and Hemostasis in the Pediatric, Geriatric, and Pregnant Populations.’ Owing to next-generation sequencing, the In-Vitro Diagnostics world continues to partition reference intervals, therapeutic target ranges, and treatments to […]

Factor IX Assay Unexpected Results

Mike Meyer asks, “we run three dilutions for all of our factor testing. Occasionally, we see results in which upon higher dilutions, the factor value decreases after adjusting for the dilution. For instance, I had a case today in which the FIX values were 0.64, 0.55, and 0.43 U/mL for the 1:10, 1:20, and 1:40 […]

Bleeding Disorders

CUSUM

From Heather DeVries, Indiana University: I’ll make this one short and sweet…how many samples should be used in a cumulative summation study? Heather, I’ve never used nor taught CUSUM, so I’m posting this in hopes of attracting comments. I did find a helpful reference, Westgard JO,Groth T, Aronsson T, de Verdler C. Combined Shewhart-cusum control […]

Lot to Lot Validation

From Maureen (Mo) Tacke, St Luke’s Health System: Hi George, our institution is coming to the joyous time of lot roll over in coagulation, and it’s got me wondering… Is our process a little (or a lot) overkill? Current process: Normal ref range studies (20 normals) for PT, PTT, FIB, AT, TT, PC, PS, DRVVT, […]

Validation: Multiple Lots

George received this question for our quality assurance experts. When validating a procedure, do you work with a single lot or multiple lots?

Multi-site Reference Intervals Revisited

Please return to our September 17, 2017 multi-site reference intervals discussion, and in particular to Heather DeVries’s comment and question about a combined INR and reportable range. So many of us are grappling with multi-site services, George hopes our participants can provide some advice on this topic. Thank you.

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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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