From Kathleen Tobertga: Hello, We are having problems between sites with the results of our 2 hour normal pooled plasma (NPP) control (unmixed) for our mixing studies. Our site (the main lab) is getting an increased value for the PTT around 40 s, which we have researched and seems to be elevated due to heat labile factors being destroyed. The other site is getting normal results for their 2 hour incubated NPP control (~32 secs). We are trying everything to figure out what is going on short of actually going over there and performing the testing ourselves. We are both using the same company for the pooled plasma, they are thawing at 37°C, we at room temp. Tommorow we will be trying to replicate each other’s thawing techinque to see if that is the variable. What I’d like to know, because I could only find it in one resource, are we correct about the heat labile factors and that the 2 hour incubated control should be increased, and do you have any place I can go to find documentation? Would be much appreciated. Thank you.
Hi, Kathleen, and thank you. Are you in the same system as Louise Pleiss, whose question I posted about an hour ago, or is this just an amazing coincidence? My hunch is you’ll find that the difference in your approaches to thawing is the key, and I await the results of tomorrow’s experiment. I know it goes without saying, but you may want to confirm that everyone is adequately mixing the thawed control. I provided one (rather old) reference to Ms. Pleiss that addresses the effect of incubation on factor VIII, and am digging through old references for others. I’ve also sent messages to several experts around the world, one of whom, Dave McGlasson, had been unable to find a reference. Please watch Fritsma Factor, as I expect to get some comments and to collect additional references in the next few days.