Specimen Management

More on Shortened PTT

From Anita Elledge, MT (ASCP), blood bank/coagulation supervisor, Sierra Vista Regional Health Center, AZ: Our coagulation testing is done on a Stago Compact instrument. The linear range is 20–200 s for the activated partial thromboplastin time (APTT, PTT). We have a policy that any PTT result <22 s must be redrawn, not just rerun the same sample, […]

Screening Assays

Rivaroxaban Specimen Stability

From Soakimi Pouhila, Auckland District Health Board, New Zealand: Hi George, any ideas on the stability of rivaroxaban in citrate samples? Hello, Soakimi Pouhila, and thank you for your question, which sent me to PubMed to see if anything has been published on rivaroxaban stability. My search was fruitless, so I’m posting your question to attract comments […]

Anticoagulant Therapy

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

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

Pediatric Collection Tubes

From Diane Belliveau, Catholic Medical Center, Manchester, New Hampshire: Hi George, we have a special care nursury. I am looking for help in specimen handling/volumes for these special patients. Are there any new products for coagulation specimen collections on babies? Hi, Diane, the only 3.2% sodium citrate tube available for low-volume collection, 1 mL, is the Greiner Bio-one […]

Specimen Management

More on “Unexpected DRVVT Results”

Here is a message about the dilute Russell viper venom time assay (DRVVT) for lupus anticoagulant (LA) from international expert Thomas Exner, HAEMATEX, Sydney, Australia: It was a pleasure to meet you at the International Society on Thrombosis and Haemostasis (ISTH) meeting recently. I would like to respond an interesting question raised on July 16, 2013 in your Fritsma Factor website. […]

Lupus Anticoagulant

Adjust D-D for HCT?

From Michael Suter, MT (ASCP) SH Senior Clinical Scientist, Hematology, Peace Health Laboratories, Springfield, Oregon. George, I am curious about your thoughts on how to best address the effect of high hematocrits (HCTs) on the quantitative latex D-dimer assays such as the Stago D-Di test. With high HCT samples, there is a relative decrease in plasma causing […]

Adjust Citrate in Severe Anemia?

From Barbara Caufield, Good Samaritan Hospital: We adjust the Na citrate volumes in coagulation tubes when the hematocrit (HCT) is > 55%. Do you recommend correcting for low HCTs? Can you tell me what formula you would use for a low HCT? At what HCT percentage do you recommend adjusting the sodium citrate? Thank you! Hello, Barbara, […]

Specimen Management

Sodium Citrate: 3.8%?

A contributor asks, “has sb reported shorter clotting times when using 3.8% (0.129M) sodium citrate tubes than 3.2% (0.109M) tubes? literature and the logic says the opposite.” Hello, and thank you for your question. I’m unsure of your reference to “sb,” however I agree that it is logical to presume that the 3.8% sodium citrate […]

Screening Assays

Hemostasis Specimen Management

I am trying to find a chart or article that tells how long plasma is good for hemostasis testing. The question has arisen about fresh samples and frozen samples. We often get requests for add-on tests and need to know how long is too long. Do you know of a resource that will provide this […]

Specimen Management

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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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