Aunna,

CLIA is an immunoassay just like RIA but with a different indicator (light emission vs radioactivity).  CLIA is reported to give lower results than RIA https://pubmed.ncbi.nlm.nih.gov/28124389/ . I don't know what assay Idexx uses (have asked but didn't get an answer). That paper is less than a year old so  maybe Cornell hasn't been investigated further yet; don't know but  I'll ask! They use a Millipore human RIA.
--
Eleanor in PA

www.drkellon.com 
EC Owner 2001