Clotted Specimens

I recently received a message from a local colleague who has received complaints from the nursing department when rejecting clotted coagulation specimens. The problem occurs with both citrated blue-closure and EDTA lavender-closure tubes. A few of the nurses are convinced the laboratory is storing the specimens too long before testing them, thus allowing them to become clotted. My colleague has provided in-services explaining the need for gentle specimen mixing immediately after collection, but has been only partially successful in convincing them that they control specimen integrity at the time of collection. I’d like to get responses from participants who face inter-departmental communication issues like this. How do you convince nurses and phlebotomists of the need to prevent hemolysis, short draws, and clotted specimens? Further, do you have any additional advice about managing pediatric specimens?

Coumadin and Factor Half-lives

I received a question recently about Coumadin (warfarin) therapy and coagulation factor half-lives. Coumadin reduces the normal carboxylation of the glutamic acid γ-carbon. There are 12–18 glutamic acid units near the amino terminus of the vitamin K-dependent factors II (prothrombin), VII, IX, and X. When vitamin K-catalyzed γ-carboxylation becomes suppressed, these coagulation factors are unable to bind Ca++ ions and consequently unable to bind platelet phosphatidyl serine, thus becoming ineffective. The same thing happens near the amino termini of control proteins C and S.

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Mixing Study: LA Effect?

Hello Mr. Fritsma! My name is Agustin Rodriguez and I am a haematologist from Spain. I have a question for you, if you are so kind to ansxwer it: I have a patient with a lupus anticoagulant. His partial thromboplastin time (PTT, aPTT) is 46 s; normal aPTT is 30 s in my laboratory. The inmediate mixing study 1:1 with normal plasma is 52 s. Can aPTT be more prolonged after mixing with normal plasma than the basal patient aPTT? In most patients with LA, the aPTT fails to correct with normal plasma but there is no prolongation over the initial aPTT. Which is the explanation for this question?
Best regards from Spain, Agustin Rodriguez, MD Haematologist, Toledo Hospital (Virgen de la Salud), Spain.

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Age-adjusted D-dimer Limit?

Hi George, I am wondering if anyone is using the age-related D-dimer cutoff for the emergency room based on the ADJUST-PE study? We use Innovance D-dimer reagents from Siemens on the BCS XP analyzer. Our ER physicians are very impatient for us to allow them to use this age-adjusted cut-off, but we have reservations due to CAP and CLIA regulations. Thanks, Sylvia Stacy, Concord Hospital, Concord, NH.

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Favorable FDA Edoxaban Vote

According to an October 30 Medscape post, Edoxaban (Savaysa, Daiichi-Sankyo) received a favorable vote, 9–1, in favor of release for once a day treatment at 30 and 60 mg to prevent non-valvular atrial fibrillation ischemic stroke. Edoxaban was found non-inferior to “in control” Coumadin in patients with mild to moderate renal impairment, but its performance in people with creatinine clearances over 80 mL/min was found to be inferior. The advisory committee vote is preliminary to FDA release of edoxaban, the final ruling could be weeks or months away.

Vascular Access Device Collection

From Nancy Fabbrini: We have a patient on an argatroban bridge to warfarin. He is a very difficult draw so the service has been drawing blood from the central access device. They have been withdrawing 20 mL of blood before drawing the tube for coagulation testing. Is that sufficient, i.e. do the same “rules” for a line with heparin apply to argatroban? Thank you.

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Pre-surgical Screening Reprise

I’d like to draw your attention to some recent responses to the November 8, 2013 post by Jeanne Isabel entry about pre-surgical screening.

Test to Assess Clotting Status

From our ASCLS Consumer Web Forum: I was wondering if there is any test available to assess the clotting status of someone with factor 5 Leiden genetic disorder to verify if the treatment plan has been effective? If the patient has been on anticoagulants, is there a test to prove that the blood-clotting issue has been resolved or at least under control? Thanks for your help!
George’s response: Thank you for your provocative question. The short answer is no, there is no laboratory test to prove the patient’s thrombotic risk is resolved, or that the anticoagulant treatment is completely effective.

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