Surreal image of child's face merging with glowing saliva droplets, representing the connection between health and non-invasive diagnostics

Stress Detectives: Can Saliva Unlock Secrets to Children's Health?

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Reese Marlowe in Health & Wellness October 2026 • 4 min read.

"New research explores how salivary biomarkers could provide a non-invasive way to measure stress responses in critically ill children, potentially leading to earlier interventions and better health outcomes."


In the high-stakes world of pediatric intensive care, doctors constantly seek better ways to understand what's happening inside their young patients' bodies. One promising avenue of exploration involves something surprisingly simple: saliva. Researchers are investigating whether measuring certain substances in saliva, known as biomarkers, can provide valuable clues about how critically ill children are responding to stress.

Why saliva? Because it offers a non-invasive window into the body's complex systems. Collecting blood samples can be stressful, especially for children already battling serious health issues. Saliva, on the other hand, is easy to obtain, making it a much gentler option. Scientists believe that analyzing salivary biomarkers like cortisol (a stress hormone), alpha-amylase (an enzyme linked to the nervous system), and immunoglobulin A (an antibody that plays a role in immunity) could offer valuable insights into a child's overall condition.

New research published in SAGE Open Medicine dives into this very topic. The study explores the potential of salivary biomarkers to measure stress responses in critically ill children, aiming to correlate these markers with disease severity and other important clinical factors. Let’s break down what the researchers discovered and what it could mean for the future of pediatric care.

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Saliva as a Pediatric Stress Measure

Salivary cortisol has been widely used in pediatric research for more than 20 years as a biomarker of hypothalamic-pituitary-adrenal axis activity during normal activity and stress responses. It is commonly used in infants and children, and studies have observed an association between maternal and infant saliva cortisol levels during the early postpartum period and the first months of life. Saliva collection is increasingly popular because it is relatively easy to obtain and handle without the specialized personnel required for blood, urine, or hair sampling. Recent research has also measured salivary cortisol and glucocorticoid receptor gene methylation for the HPA axis, alongside salivary alpha-amylase for the sympathetic-adrenal-medullary system.

From Laboratory Measure to Pediatric Research Tool

Salivary cortisol emerged as a potential biological measure of stress in research with children, supported by laboratory techniques capable of detecting very small cortisol concentrations in plasma and saliva. By 2019, the measurement of salivary cortisol had been widely used in pediatric research for more than 20 years to assess HPA-axis activity during ordinary conditions and responses to stress. Historical reviews describe the integration of stress biomarkers into studies of childhood health, risk, and resilience, including research on how early-life adversity affects cortisol secretion. The literature also reports cognitive-behavioral interventions that reduced pain and distress in children undergoing intravenous needle procedures.

Decoding Salivary Biomarkers: What the Study Revealed

Surreal image of child's face merging with glowing saliva droplets, representing the connection between health and non-invasive diagnostics

The study, conducted over a two-year period, enrolled 79 children admitted to a pediatric intensive care unit (PICU). Researchers collected saliva samples at three specific times of day – 8 a.m., 2 p.m., and 8 p.m. – to examine potential disruptions in the body's natural daily rhythms. Ultimately, data from 65 patients were analyzed.

So, what did the saliva samples reveal? Here's a breakdown of the key findings:

  • Elevated Biomarkers: Overall, the levels of salivary biomarkers were increased in the critically ill children compared to what's typically seen in healthy children.
  • Cortisol Rhythms Disrupted: The normal daily pattern of cortisol secretion was often disturbed, particularly in children with higher Pediatric Risk Index of Mortality (PRISM) scores, indicating more severe illness.
  • Age Matters: Children younger than 6 years old showed significantly higher cortisol and IgA levels.
  • Amylase Holds Steady: While cortisol rhythms were disrupted, alpha-amylase rhythms tended to remain more stable, especially in children with shorter hospital stays.
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A Broader Salivary Biomarker Panel

Recent reviews describe salivary biomarkers as tools for tracking stress, anxiety, pain responses, and therapy outcomes in healthy and medically complex children. Salivary alpha-amylase and secretory immunoglobulin A are identified as two prominent measures of acute stress response. In pediatric dental research, salivary cortisol has shown positive correlations with dental fear, stress, and anxiety, especially among returning patients. By contrast, findings for salivary alpha-amylase and secretory immunoglobulin A have been inconsistent.

Inconsistent Signals

Evidence does not support treating every salivary marker as a consistent indicator of pediatric stress. Studies summarized in a 2025 review found positive correlations between salivary cortisol and dental fear, stress, and anxiety, particularly in returning dental patients. The same review reported inconsistent findings for salivary alpha-amylase and secretory immunoglobulin A, with only some studies linking them to dental fear or previous dental experiences. A separate report cited a small sample of healthy children aged 1 to 10 years with median SIgA levels of 4.26 ± 3.85 mg/dL, illustrating the limited reference evidence available for some markers.

Choosing Biomarkers for Chronic Stress

A 2018 review examines biomarkers of chronic stress in children and adolescents, along with collection strategies, possible moderators, and future directions for biobehavioral research. It emphasizes that biomarker selection must account for the methods used to collect samples and the factors that may influence measurements. The review presents chronic-stress biomarkers as a way to investigate links between adversity and health, rather than as a single definitive test.

These findings suggest that salivary biomarkers can indeed reflect the stress responses of critically ill children. The disrupted cortisol rhythms, in particular, seem to be linked to disease severity. But what does this mean in practice?

The Future of Salivary Biomarkers in Pediatric Care

This research offers a promising glimpse into the potential of salivary biomarkers as a non-invasive tool for assessing stress in critically ill children. While more research is needed, these findings suggest that measuring substances in saliva could help doctors identify high-risk children earlier, guide treatment decisions, and ultimately improve the quality of care. The next step involves larger studies to confirm these findings and explore how salivary biomarkers can be integrated into existing clinical practices. By unlocking the secrets hidden within saliva, we may be able to provide more personalized and effective care for our most vulnerable young patients.

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Toward More Responsive Monitoring

Salivary cortisol and salivary alpha-amylase are often used as biomarkers when studying stress in children undergoing surgical or endoscopic procedures. The source material also notes that sensing technologies are available for detecting stress biomarkers in saliva and other fluids. This points toward future monitoring approaches that could combine noninvasive saliva collection with developing detection technologies. The evidence provided supports this as an emerging direction, not as an established clinical standard.

Limited Guidance for Chronic-Stress Research

Biomarkers of chronic stress may help pediatric researchers clarify how exposure to adversity relates to lifelong health. However, a 2018 review reports that there are currently very few parameters to guide nurse researchers in choosing appropriate chronic-stress biomarkers for children and adolescents. This lack of guidance affects decisions about which biomarkers to collect and how to interpret them. Saliva therefore offers research potential while still requiring careful methodological choices.

Reducing Distress Through Care

Salivary biomarkers can provide information about HPA-axis activity under normal conditions and in response to psychological or physical stress. Research in critically ill children has examined salivary cortisol, alpha-amylase, and immunoglobulin A in relation to the Pediatric Risk Index of Mortality. Separately, evidence summarized in the source material indicates that non-pharmacological interventions can reduce anxiety or distress in children, with saliva cortisol providing supporting measurements. These applications connect saliva-based research with both clinical assessment and efforts to make pediatric care less distressing.

Putting the cortisol comparison in context

  • 79.80 versus 25.80At 2 p.m., the high-severity group’s cortisol average was 79.80, compared with 25.80 in the lower-severity group; the reported difference was statistically significant.[1] [2]

Limits noted in the study

  • Age, sex, and underlying illness may affect biomarker measurements, so the observed links are preliminary rather than proof that the markers estimate stress or outcome.[1]
  • The authors noted that only higher afternoon cortisol was observed in this group, possibly reflecting the cohort’s small size; alpha-amylase rhythm was often disrupted.[1] [2]

What researchers measured in critically ill children

Study designObservational study[2]
Sample size65 children[2]
Duration2-year study period[2]
Effect sizeHigh-gravity group had higher cortisol at 2 p.m. (79.80 ± 88.21 vs 25.80 ± 24.71)[2]
p-valuep = 0.036[2]
Times cited17[2]

How this study fits with related work

The paper’s cited healthy-child reference range for morning cortisol is 0–25 nmol/L, while a cited report on critically ill children gives a much broader cortisol range of 7.7–448.3 nmol/L. These comparisons come from separate reports and do not establish a direct difference between matched groups.[1]

Questions the measurements leave open

  • Would the associations between marker patterns and illness severity persist when age, sex, and underlying disease are accounted for?[1] [2]
  • How might puberty, sleep disruption, or the timing and conditions of sample collection affect the observed patterns?[1] [3]

Sources

  1. Salivary biomarkers may measure stress responses in critically ill children (Europe PMC, 2018)
  2. Salivary biomarkers may measure stress responses in critically ill children (SAGE Publications, 2018)
  3. Measurement and meaning of salivary cortisol: a focus on health and disease in children. (pubmed.ncbi.nlm.nih.gov)

About this Article -

Written with AI assistance from published research, and reviewed by the Mystum team. See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1177/2050312118802452, Alternate LINK

Title: Salivary Biomarkers May Measure Stress Responses In Critically Ill Children

Subject: General Medicine

Journal: SAGE Open Medicine

Publisher: SAGE Publications

Authors: Despoina Tzira, Anargyroula Prezerakou, Ioannis Papadatos, Artemis Vintila, Anastasia Bartzeliotou, Filia Apostolakou, Ioannis Papassotiriou, Vassiliki Papaevangelou

Published: 2018-01-01

Everything You Need To Know

1

What are salivary biomarkers, and how are they used in this context?

The article introduces the use of salivary biomarkers as a non-invasive method to measure stress responses in critically ill children. These biomarkers, such as cortisol, alpha-amylase, and immunoglobulin A, are measured from saliva samples. This approach aims to offer a less stressful way to monitor a child's health compared to traditional methods like blood samples. The research suggests a correlation between these biomarkers and the severity of the child's illness, potentially aiding in earlier interventions and better health outcomes.

2

Why is cortisol significant in this research, and what do the findings suggest?

Cortisol is a stress hormone, and its levels and rhythms can be indicators of stress in the body. In the context of the research, measuring cortisol levels in saliva helps assess the stress responses of critically ill children. The study found that the normal daily patterns of cortisol secretion were disrupted in children with more severe illnesses, as indicated by higher Pediatric Risk Index of Mortality (PRISM) scores. This disruption is significant because it suggests that salivary cortisol can be a valuable marker for disease severity, potentially allowing for more timely interventions.

3

What role does alpha-amylase play in this study, and what were the key findings related to it?

Alpha-amylase is an enzyme linked to the nervous system and is another biomarker investigated in the research. The study examined how alpha-amylase levels varied in critically ill children. The findings indicated that while cortisol rhythms were often disrupted, alpha-amylase rhythms tended to remain more stable, especially in children with shorter hospital stays. This stability suggests that alpha-amylase could be less directly affected by the immediate stress of critical illness compared to cortisol, and may offer different insights into the child's condition and stress response.

4

What specific biomarkers were analyzed, and what were the key findings regarding them?

The study specifically looked at three biomarkers: cortisol, alpha-amylase, and immunoglobulin A (IgA). Cortisol is a stress hormone, alpha-amylase is an enzyme linked to the nervous system, and IgA is an antibody that plays a role in immunity. The research found that the levels of these salivary biomarkers were generally elevated in critically ill children compared to healthy children. Moreover, children under 6 years old showed significantly higher cortisol and IgA levels. These findings suggest that these biomarkers can reflect stress responses, disease severity, and even age-related differences in critically ill children.

5

Where was the research conducted, and why is it important to the study's implications?

The Pediatric Intensive Care Unit (PICU) is the setting where the study was conducted. In this high-stakes environment, doctors constantly seek better ways to understand what's happening inside young patients' bodies. The research explored the use of salivary biomarkers to measure stress responses in critically ill children within the PICU, collecting saliva samples at specific times of day to observe the body's natural rhythms. Findings in the PICU could help doctors identify high-risk children earlier, guide treatment decisions, and ultimately improve the quality of care.

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