Charlie Muller, Helen Hayes Hospital TW, posted a question on the Medlab list, paraphrased here with his permission. He is validating the Akers PIFA Heparin/PF4 rapid assay kit for heparin induced thrombocytopenia with thrombosis, and needs a good way to validate it in addition to using Akers’ panels. Charlie’s setting is an acute rehab specialty hospital where a very large majority of patients have been exposed to heparin in various surgical procedures. They consult with a pathologist from Columbia University Medical Center who has had several discussions with the medical staff about HIT being a clinical diagnosis, using Warkentin’s 4T, etc. The staff want a little extra guidance from a rapid lab test.
From Yvonne Ellis, Hematology Technical Supervisor, IU Health Bedford Laboratory: George, I counseled a physician today about ordering protein C and S on a patient who has a confirmed pulmonary embolism. I told him during a clot was not the time to test for these. He did seem to have a good understanding of the workings of the regulators. He seemed to think though that if someone normally had low levels of these, that the levels would be markedly decreased during a clot process. I told him there is no established evidence of how much prot C and prot S are decreased in a clot formation. It would be different per person and per clot. Was I correct in this? Have there been studies about this subject?
I enjoy the e-mails I receive from the Fritsma Factor. I teach hematology/coag at a 2 year MLT program and use the text you collaborated on with Prof. Rodak. It is a great text. Thank you for any help.
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From our frequent contributor Crystal Azevedo, Eastern Maine Health System: Hello George, I am working up more patients taking the new directed oral anticoagulants (NOACs) for therapy. Is there a relationship between rivaroxaban and an elevated plasma homocysteine level? I have seen this more than once and I’m curious. Thanks!
Dear George, I work in a large midwest reference laboratory. We are looking at bringing in the Prot S free latex test. Have you seen any comparison studies between manufacturers’ kits that I could go out on the internet and read? Thanks, Pamela L. Pool, Section Specialist for Coagulation.
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, because it is said that a low PTT result should not occur and is almost always due to a bad collection. I can’t seem to find any documentation that confirms the < 22 s result being a point for this “recollect.” Can you give me a resource for information or any further help with this?
Hans Zwerger, Produktspezialist at CoaChrom Diagnostica, Vienna, Austria introduced me to an important clinical issue, anti-platelet factor 4 (PF4)/protamine antibodies that are implicated in heparin-induced thrombocytopenia with thrombosis (HIT). As you know, cardiologists employ high doses of standard unfractionated heparin during coronary artery bypass graft surgery, which anesthetists and anesthesiologists measure using the activated clotting time assay or thromboelastography. Near the completion of surgery, the heparin is reversed using protamine sulfate, a DNA-binding protein extracted from salmon sperm. Reversal is also monitored the same way.
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.