Hi George, If I want to show the effect of lipemia on coag test before and after spiking a single sample, is the % difference between the baseline and spiked results enough? How do you show whether there is a statistical or clinical difference, and what stat tool to use? Thanks, Marc.
Hello, and thank you for this thought-provoking question. I can’t think of a way to spike samples so as to simulate lipemia, however in a discussion with Dr. Larry Brace, we suggest you isolate samples as they arrive in the lab, aliquot, ultracentrifuge one aliquot to precipitate the lipemic particles, and run coagulation tests on the uncentrifuged and centrifuged aliquots. You can use the paired Student t-test to compare the means of results for a statistical difference. If you do this, I recommend you publish the results in one of the clinical lab-directed journals such as Clinical Laboratory Science, as it will be helpful for many of us. One confounding factor related to ultracentrifugation is that it may also precipitate the larger VWF multimers, so you may want to include a VWF activity assay in your experiment. I wish you success.
If you are looking to spike
If you are looking to spike samples, Intralipid can be used. A tiny bit goes a long way. Unfortunately, I don’t have any specific details on how to do it, but I have been involved with studies where this was done.
Hi, Marc, More information how to deal with lipemia in clinical laboratories (not only hemostatic tests) was recently reviewed here: Lipemia: causes, interference mechanisms, detection and management; http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3936974/
As an example of research approach in coag. testing is described here:
Ultracentrifugation appears to be a viable method to eliminate interference from gross lipemia for some specialized coagulation assays https://www.aruplab.com/Research&Development/resources/Posters/2013/Crist_%20ISLH_0513.pdf