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Positive DRVVT when Mixing Study Corrects

From Aliaa Amer: Hi George, we are using Actin FSL for our routine activated partial thromboplastin time (APTT, PTT). Whenever we get a prolonged APTT that is >5 s above the upper limit of the norm range we do mixing studies, both immediate and 2 h incubation using 1:1 and 4:1 mix, the latter to detect […]

Lupus Anticoagulant

Hepzyme Interference?

From Crystal Azevedo, “Are there any substances known to interfere with the neutralization of heparin by the Dade (Siemens) Hepzyme product? We recently worked on a patient sample that I am told had absolutely NO heparin in it, yet the PTT decreased from >200 seconds to 89 seconds after treatment. Thanks!” Hi, Crystal, and thanks for […]

Specimen Management

Rivaroxaban Measurement by Anti-Xa

Dave McGlasson forwarded Samama MM, Contant G, Spiro TE, Perzborn E, Le Flem L, Guinet C, Gourmelin Y, Rohde G, Martinoli JL. Laboratory assessment of rivaroxaban: a review. Thromb J. 2013;11:11–18, linked below. The article supports measuring rivaroxaban with the chromogenic anti-Xa assay using rivaroxaban calibrators and controls, and concedes that the prothrombin time (PT) in […]

Anticoagulant Therapy

WFH Research RFP

The Word Federation of Hemophilia has just issued a research request for proposals. This is short notice, however, if you have a proposal, WFH will accept a letter of intent by August 31, 2013. Click WFH RFP for submission details.

Bleeding Disorders

Bio-Rad Event 9/20; Rancho Mirage

Mark your calendar for Friday, September 20, 2013 when Bio-Rad and Sysmex host a free continuing education event: A Focus on Hematology and Coagulation at the Eisenhower Medical Center, Annenberg Center for Health, Rancho Mirage, CA 92840. George will speak 1:00–2:30 on “Managing the New Anticoagulants, Whatever Happened to the PT and PTT?” Click here to register. Bio-Rad Event 9-20-13

Change in Actin FS Sensitivity

Here is a new message from frequent contributor Joyce Low at St. Vincent’s in Sydney. “Our lab has been using Actin® FS since 2007. For us, different lot numbers have been reasonably similar in terms of the reference interval 25–35 s on Stago instruments and heparin therapeutic interval of 50–75 or 80s determined by anti-Xa assay. In […]

Anticoagulant Therapy

Does Lipitor Affect INR?

I received this August 6 note from Prof. Emeritus Bernadette Rodak, Indiana University Clinical Laboratory Science program. Prof. Rodak responds to questions posted by patients to the ASCLS Consumer Web Forum and passed this along for comment: “I have a question from a patient whose INR suddenly jumped to over 7 when he started atorvastatin (Lipitor®). I found […]

Anticoagulant Therapy

D-dimer Discrepancy

From Suakimi Pouhila, Auckland District Health Board, New Zealand. We have a patient which showed high D-dimer results with Siemens’ Innovance D-dimer but normal Stago D-dimer results. Has anyone seen this before? Is this due to cross reaction with a heterophile antibody? Hello, Suakimi Pouhila, and thank you for your question. The various monoclonal antibodies that are […]

Erratic PTT

George received a note from a colleague who has three separate specimens from a patient with prolonged partial thromboplastin times (PTTs) that further prolong as they stand at ambient temperature over periods of several minutes, for instance, 57s, 151s after 20 minutes, and 174s after 2 hours. Mixing studies consistently correct. They’ve tested them on […]

Specimen Management

LA Protocol

From Michelle Fahs, Mercy Hospital, St. Louis. Hi, we are going to start performing lupus anticoagulant testing and are planning to perform the PTT–LA and dilute Russell viper venom time (DRVVT). We use Stago instrumentation. We are still determining our testing algorithm from that point and I have a few questions for you. 1. Do you recommend […]

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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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