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Mixing Studies and the Thrombin Time

This question arrived as a comment from “skierktc;” I have reproduced it as a post here: I am preparing to update our laboratory’s procedure for prothrombin time (protime, PT) and partial thromboplastin time (PTT) mixing studies and wonder if anyone screens additionally with the thrombin clotting time (TCT, TT) or the TT plus protamine sulfate […]

Mixing Studies Interpretation

A question about mixing studies from Stacy Askvig at the University of North DakotaMedical Center. Stacy’s question arrived via Lab Tests Online and the American Society for Clinical Laboratory Science Consumer Forum: I do only PTs and PTTs, and my references seem to give me conflicting interpretations. Our patient has a prolonged PTT and DRVV, both are shortened in mixing studies: […]

Anti-Xa and Lipemia

From “McDowekm:” We currently perform anti-Xa heparin testing on a hybrid curve using Stago’s Rotachrom reagent on our Stago Compact. If we have a specimen that is lipemic, it can falsely increase the anti-Xa result. Can these specimens be ultra-centrifuged to obtain a more accurate Anti-Xa result? Hello and thank you for your question. It […]

Heparin Recall, 10-27-10

Steve Duff of Precision BioLogic alerts us to a new recall of unfractionated heparin posted by the US FDA on October 27, 2010. The supplier, Scientific Protein Laboratories, in testing retained crude heparin lots revealed traces of oversulfated chondroitin sulfate. This is the same problem that created a public health risk in 2008. Select US FDA […]

Factor Substitution Assays

There has been some new discussion of the obsolete factor substitution assays using aged serum and adsorbed plasma on the CLS Educators’ List. These have been long discontinued, but a handful of we educators are still teaching them. Here is an earlier discussion on factor substitution assays. Geo.

New Quick Question Posted

A new November Quick Question on specimen management was posted Tuesday, November 9, 2010.

Quick Question: Pooled Normal Plasma

Here is our October Quick Question and its results: What form of platelet-poor pooled normal plasma (PNP) does your laboratory used for mixing studies? a. Commercially prepared frozen PNP: 71 (73%) b. Commercially prepared lyophilized PNP: 11 (11%) c. Locally prepared frozen PNP: 9 (9%) d. Fresh plasma from a normal control: 6 (6%) Answer […]

Do Not Use Heat Blocks

Here is an important follow-up message from Lisa Reid-Fifoot at Precision about heat blocks: Hi George, I was reading the question from Kim Kinney regarding the use of a water bath or a heating block to thaw frozen coag samples and I wanted to share some information. Precision BioLogic strongly discourages the use of a heating block. We […]

Mixing Studies: 4:1?

Here are two new questions from “mirnaibarra” in El Paso. George, Thank you for your prompt answer to my last question. We are setting up mixing studies for PT and PTT and I found some literature that states that a 4:1 mix is more sensitive than the 1:1 mix. Do you recommend the 4:1 mix […]

Thawing Coag Specimens: Heat Block?

Another great question from Kim Kinney at Clarian in Indy: Clarian’s newest affiliate, Ball Memorial in Muncie, IN will be opening their new lab the first of December. We are purchasing small equipment and the subject of a water bath came up. At Clarian we have always used a 37ºC water bath to thaw our frozen coagulation samples […]

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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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