Discussion paper on ‘comparing the agreement of a commercial cortisol kit with a biologically validated assay in evaluating faecal cortisol metabolite levels in koala joeys’

This Discussion paper is in response to the article 'comparing the agreement of a commercial cortisol kit with a biologically validated assay in evaluating faecal cortisol metabolite levels in koala joeys’, which compared two cortisol enzyme immunoassays (EIAs), the Arbor Assay cortisol kit and the validated R4866 cortisol assay. Our concerns relate to the experimental design and arguments in the introduction and discussion used to suggest the suitability of the cortisol EIA kit. We analyse some of the statements and respond by presenting information based on current scientific knowledge.