We’ve just posted a new Quick Question, and have already received this response from Heather DeVries, Indiana University Health.
I just logged in and saw the new Quick Question. I am excited to be the first to respond! Of course my answer is not simple. As a system, we use close to 300 normals to create our PT reference range. We require each site to use 20 normals to establish their geomean, and I throw everyone in together for the all-site reference range. For PTTs, we have collected fewer, but still well over 120. At IUHPL, we run 20, but all other sites run 10. For specialty assays, we validate with 30 normals. The logistics of collecting and running 120 for a special coag assay is overwhelming and too costly, in our opinion.
Thanks to Heather for this insight, and please send George your reference interval comments at [email protected], as this information will be extremely helpful to others with similar requirements.