Background: Human saliva is a valuable and flexible source of endocrine biomarkers, from which several significant steroids representing indices of development, well being, stress and reproduction can be quantified. Although for many disciplines blood represents the gold standard for endocrine measurement, it also has its limitations, specifically requiring trained phlebotomists and appropriate facilities. The painful and invasive nature of blood draws can deter research participation and restricts frequent collection. Alternatively, saliva collection is straightforward in settings beyond clinical and laboratory boundaries and advances our access to populations and behavioural contexts for which blood sampling is unfeasible.
Objectives: This validation project investigates optimal protocols to adopt when collecting and storing saliva to improve reliability and increase comparability across research sites and studies. Our primary objective was to investigate and validate methods to successfully preserve saliva in a manner compatible with Enzyme Immuno-Assay (EIA). Identification of a preservation method could enhance flexibility of both field site conditions and collection protocols. This work is critical as previously established preservatives, such as sodium azide that were compatible with RIA, interfere with Horseradish Peroxidase commonly found in most EIA preparations.
Methods: Ethical Approval was granted by the local recognised University Ethics Committee. Raw human saliva samples were collected, spiked with different concentrations of the preservative Proclin300 and stored at room temperature. Following defined time periods (7d, 1, 3 and 6 months) samples were analysed for reproductive steroids using commercially available EIA kits, estradiol and progesterone.
Results and conclusions: Early results suggest that Proclin300 has potential for preserving saliva samples. Further novel preservation data are presented. We also report the stability of saliva content in conjunction with collection vial material (e.g. polystyrene, polypropylene). Such validation data are essential to further develop opportunities to capture endocrine profiles that are beyond reach of clinical settings.