Within‐Subject Variability in Repeated Measures of Salivary Analytes in Healthy Adults

Abstract

Background Saliva contains a large number of biomolecules, some of which have putative diagnostic usefulness. A potential problem with the use of biomolecules in diagnosis is day-to-day fluctuation due to within-subject variability. This study evaluated the intraindividual variability of six salivary analytes in healthy adults and determined their normal range. Methods Unstimulated whole saliva (5 ml) was collected every 2 to 3 days on six occasions from 30 subjects in good oral and systemic health. Four of the samples were collected in the clinic, and two were collected by the subject at home. The concentration ranges of interleukin (IL)-1β, IL-6, matrix metalloproteinase-8, prostaglandin E2, tumor necrosis factor-alpha, interferon-alpha, and albumin were examined. Descriptive statistics were computed, and a one-way random-effects model was used to quantify within- and between-subject components of variability. Intraclass correlation coefficients (ICCs) were calculated for each subject/analyte combination. Results Within-subject coefficients of variation for these analytes ranged from 67.6% to 172.1% for the in-clinic samples and from 111.9% to 201.0% for the at-home samples. The ICC for the various analytes ranged from 41% to 61% for the in-clinic samples. The at-home samples exhibited significantly more variability than did those obtained in the clinic under supervision. Conclusions There was marked within-subject variation in the salivary concentrations of these analytes. With increased interest in salivary diagnostics, the within-subject variability, normal range, and threshold levels for abnormal levels of individual salivary analytes need to be determined if these diagnostics tests are to have clinical usefulness.

Circadian Rhythms of Urinary Cortisol Levels Vary Between Individuals in Wild Male Chimpanzees: A Reaction Norm Approach

“…A fair share of scientific effort in this line of research has focused on individual repeatability of glucocorticoid levels (e.g., Hruschka et al, 2005;Bonier et al, 2009;Thomas et al, 2009;Dingemanse et al, 2010a;Flinn et al, 2011;Ouyang et al, 2011a;Brommer, 2013;Cockrem, 2013;Narayan and Hero, 2013;Baugh et al, 2014;Hau et al, 2016). Glucocorticoids are a group of steroid hormones that function as physiological mediators to deal with metabolic demands arising from internal (e.g., metabolic) and external (e.g., ecological) circumstances (Sapolsky et al, 2000;Romero et al, 2009;Wingfield, 2013).…”

Saliva proteomics as an emerging, non-invasive tool to study livestock physiology, nutrition and diseases

“…In addition, whole saliva collected over a 2-week period showed marked within-subject variation in the concentrations of IL-1b and -6, MMP-8, PGE2, TNF-a, IFN-a, and albumin in a group of periodontally and systemically healthy adult subjects [76]. Finally, it has been concluded that before salivary diagnostics and point-of-care systems employing saliva could be used as diagnostic and screening tools, the normal variability of salivary analytes needs to be considered to create accurate thresholds enabling the definition of abnormal/pathological values [76].…”

Serum and salivary cardiac analytes in acute myocardial infarction related to oral health status

“…While a limited number of analytes for both local and systemic diseases have been identified in saliva, biomarker discovery and validation depends upon an understanding of normal day-to-day variations 22,47 in a particular analyte, as well as identification of health states that would alter the analyte values. The current study evaluated key biomarkers of cardiovascular disease, including inflammation and myocardial damage in serum and saliva and documented effects of oral health/disease on the levels of these analytes in the fluids.…”

“…[17][18][19][20][21] It has been shown that numerous salivary analytes, while demonstrating some variation in healthy subjects, remain capable of delineating oral disease from health. [22][23][24][25][26] However, since a number of salivary biomarkers of AMI are components of the chronic inflammatory cascade, and periodontal disease has an association with cardiovascular disease, it remains to be determined if oral disease contributes to alterations in either salivary or serum analyte levels that could impact clinical studies of cardiovascular disease. [27][28][29][30][31][32] This report compares levels of specific biomarkers associated with cardiovascular inflammation in serum and saliva between patients presenting with diagnosed AMI and control subjects.…”