Yesterday, January 21, 2014, I posted “Incubated PT Mixing Studies?” in response toLori Pinelli, and mentioned a patient Dave McGlasson worked up who had a Keflex-induced anti-factor V. The post attracted a comment from my colleague at Precision BioLogic Inc, Ali Sadeghi-Khomami, PhD, and just a few moments ago I added a comment emailed to me by Chris Ferrell at University of Washington Harborview. Both comments are insightful and provocative. As they say on TVLand, “BUT WAIT, THERE’S MORE!”
Here is an additional comment from Mr. McGlasson: George, I have attached a copy of the paper I discussed with you yesterday about the factor V inhibitor with some unusual results that increased upon incubation. I realize that the platelet neutralization procedure (PNP) and the kaolin clotting time (KCT) tests may be dated but later follow-up testing showed it to be STACLOT-LA negative but the DRVVT screen and confirm were both positive. Let me know what you think.
I couldn’t add Dave’s comment below Chris’s because the comment function doesn’t allow me to link a publication, so I’ve entered this new post with a link from the 1990 volume of Clinical Laboratory Science. The publication link is below, and yes, it is upside down (at least on my computer), but it is well worth the extra effort to rotate it, as it is a very interesting read.
Posted by George on behalf of a local colleague: We just inc
Posted by George on behalf of a local colleague: We just incubate all our mixes. Most of the time, we’re mixing both PT and PTT, so it’s not worth doing an immediate mix and then risk having to turn around and incubate it. One of the patients I can think of who did have a factor V inhibitor–which I’m pretty sure was because of bovine thrombin–we happened to do an immediate mix on and neither side corrected. But even if it’s just a PT mix and the PTT is normal, we still incubate it.