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Measurement of cortisol in saliva: a comparison of measurement error within and between international academic-research laboratories

TitleMeasurement of cortisol in saliva: a comparison of measurement error within and between international academic-research laboratories
Publication TypeJournal Article
Year of Publication2017
AuthorsCalvi, JL, Chen, FR, Benson, VB, Brindle, E, Bristow, M, De, A, Entringer, S, Findlay, H, Heim, C, Hodges, EA, Klawitter, H, Lupien, S, Rus, HM, Tiemensma, J, Verlezza, S, Walker, CD, Granger, DA
JournalBMC Res Notes
Volume10
Pagination479
Date PublishedSep 13
ISBN Number1756-0500
Accession Number28903752
KeywordsInter-assay, Inter-laboratory variation, Intra-assay, Salivary cortisol
Abstract

OBJECTIVE: Hundreds of scientific publications are produced annually that involve the measurement of cortisol in saliva. Intra- and inter-laboratory variation in salivary cortisol results has the potential to contribute to cross-study inconsistencies in findings, and the perception that salivary cortisol results are unreliable. This study rigorously estimates sources of measurement variability in the assay of salivary cortisol within and between established international academic-based laboratories that specialize in saliva analyses. One hundred young adults (Mean age: 23.10 years; 62 females) donated 2 mL of whole saliva by passive drool. Each sample was split into multiple- 100 microL aliquots and immediately frozen. One aliquot of each of the 100 participants' saliva was transported to academic laboratories (N = 9) in the United States, Canada, UK, and Germany and assayed for cortisol by the same commercially available immunoassay. RESULTS: 1.76% of the variance in salivary cortisol levels was attributable to differences between duplicate assays of the same sample within laboratories, 7.93% of the variance was associated with differences between laboratories, and 90.31% to differences between samples. In established-qualified laboratories, measurement error of salivary cortisol is minimal, and inter-laboratory differences in measurement are unlikely to have a major influence on the determined values.

PMCID

PMC5598071