Determination of salivary cortisol by ELISA and its application to the assessment of the circadian rhythm in children

Spatially and temporally resolved metabolome of the human oral cavity

Saliva is a complex bodily fluid composed of secretions by major and minor salivary glands. Salivary glands and their secretions are known to be unevenly distributed in the human oral cavity. Moreover, saliva flow rate and composition vary across locations and time of the day. This remarkable heterogeneity of salivary secretions suggests that different subtypes of saliva fulfill different functions. By coupling a non-invasive and facile collection method with comprehensive metabolomic profiling, we investigated the spatial and temporal distributions of salivary components. We identified location-specific metabolite profiles, novel oscillating metabolites, and location-specific diurnal patterns. In summary, our study paves the way for a deeper and more comprehensive understanding of the complex dynamics and functionalities of the salivary metabolome and its integration in multi-omics studies related to oral and systemic (patho-)physiology.

Advances in electrochemical biosensor design for the detection of the stress biomarker cortisol

The monitoring of stress levels in humans has become increasingly relevant, given the recent incline of stress-related mental health disorders, lifestyle impacts, and chronic physiological diseases. Long-term exposure to stress can induce anxiety and depression, heart disease, and risky behaviors, such as drug and alcohol abuse. Biomarker molecules can be quantified in biological fluids to study human stress. Cortisol, specifically, is a hormone biomarker produced in the adrenal glands with biofluid concentrations that directly correlate to stress levels in humans. The rapid, real-time detection of cortisol is necessary for stress management and predicting the onset of psychological and physical ailments. Current methods, including mass spectrometry and immunoassays, are effective for sensitive cortisol quantification. However, these techniques provide only single measurements which pose challenges in the continuous monitoring of stress levels. Additionally, these analytical methods often require trained personnel to operate expensive instrumentation. Alternatively, low-cost electrochemical biosensors enable the real-time detection and continuous monitoring of cortisol levels while also providing adequate analytical figures of merit (e.g., sensitivity, selectivity, sensor response times, detection limits, and reproducibility) in a simple design platform. This review discusses the recent developments in electrochemical biosensor design for the detection of cortisol in human biofluids. Special emphasis is given to biosensor recognition elements, including antibodies, molecularly imprinted polymers (MIPs), and aptamers, as critical components of electrochemical biosensors for cortisol detection. Furthermore, the advantages and limiting factors of various electrochemical techniques and sensing in complex biofluid matrices are overviewed. Remarks on the current challenges and future perspectives regarding electrochemical biosensors for stress monitoring are provided, including matrix effects (pH dependence and biological interferences), wearability, and large-scale production.

The Relationship between Psychological Suffering, Value of Maternal Cortisol during Third Trimester of Pregnancy and Breastfeeding Initiation

Background and Objectives: Cortisol, the stress hormone, is an important factor in initiating and maintaining lactation. Maternal suffering during pregnancy is predictive for the initiation and shorter duration of breastfeeding and can also lead to its termination. The aim of this study is to evaluate the relationship between the level of salivary cortisol in the third trimester of pregnancy and the initiation of breastfeeding in the postpartum period in a cohort of young pregnant women who wanted to exclusively breastfeed their newborns during hospitalization. Materials and Methods: For the study, full-term pregnant women were recruited between January and May 2022 in the Obstetrics and Gynecology Clinic of the Mureș County Clinical Hospital. Socio-demographic, clinical obstetric and neonatal variables were collected. Breastfeeding efficiency was assessed using the LATCH Breastfeeding Assessment Tool at 24 and 48 h after birth. The mean value of the LATCH score assessed at 24 and 48 h of age was higher among mothers who had a higher mean value of salivary cortisol measured in the third trimester of pregnancy (p < 0.05). A multivariate logistic regression model was used to detect risk factors for the success of early breastfeeding initiation. Results: A quarter of pregnant women had a salivary cortisol level above normal limits during the third trimester of pregnancy. There is a statistically significant association between maternal smoking, alcohol consumption during pregnancy and the level of anxiety or depression. Conclusions: The most important finding of this study was that increased salivary cortisol in the last trimester of pregnancy was not associated with delayed initiation/absence of breastfeeding.

Influence of iron supplementation on fatigue, mood states and sweating profiles of healthy non-anemic athletes during a training exercise: A double-blind, randomized, placebo-controlled, parallel-group study

Iron is specifically important to athletes, and attention has grown to the association between sports performance and iron regulation in the daily diets of athletes. The study presents new insights into stress, mood states, fatigue, and sweating behavior among the non-anemic athletes with sweating exercise habits who consumed a routine low dose (3.6 mg/day) of iron supplementation. In this double-blind, randomized, placebo-controlled, parallel-group study, both non-anemic male (N = 51) and female (N = 42) athletes were supplemented either with a known highly bioavailable iron formulation (SunActive® Fe) or placebo during the follow-up training exercise period over four weeks at their respective designated clinical sites. The effect of oral iron consumption was examined on fatigue, stress profiles, as well as the quality of life using the profile of mood state (POMS) test or a visual analog scale (VAS) questionnaire, followed by an exercise and well-being related fatigue-sweat. Also, their monotonic association with stress biomarkers (salivary α-amylase, salivary cortisol, and salivary immunoglobulin A) were determined using spearman's rank correlation coefficient test. Repeated measure multivariate analysis of variance (group by time) revealed that the total mood disturbance (TMD) score was significantly lower (P = 0.016; F = 6.26) between placebo and iron supplementation groups over the four weeks study period among female athletes. Also, a significant reduction in tired feeling/exhaustion after the exercise (P = 0.05; F = 4.07) between the placebo and iron intake groups was noticed. A significant within-group reduction (P ≤ 0.05) was noticed in the degree of sweat among both male and female athletes after 2 and 4 weeks of iron supplementation, while athletes of the placebo intake group experienced a non-significant within-group reduction in the degree of sweat. Overall, the result indicates routine use of low dose (3.6 mg/day) iron supplementation is beneficial for non-anemic endurance athletes to improve stress, mood states, subjective fatigue, and sweating conditions.

Sweat Cortisol and Cortisone Determination in Healthy Adults: UHPLC-MS/MS Assay Validation and Clinical Application

A simple and effective ultra-high-performance liquid chromatography assay linked to tandem mass spectrometry (UHPLC-MS/MS) for measuring cortisol and cortisone levels in human sweat has been developed and validated. A noninvasive world standard sweat collecting equipment was utilized to collect samples. The samples were analyzed using an Atlantis dC18 (2.1 × 100 mm, 3 μm) column with a 2 mM ammonium acetate and acetonitrile (1 : 1, v : v) mobile phase. In an isocratic condition, the mobile phase was delivered at a flow rate of 0.3 ml/minute. A positive electrospray ionization interface with multiple-reaction monitoring mode was used to provide simultaneous quantification of cortisol, cortisone, and internal standard at transitions of 363.11 to 121.00, 361.18 to 163.11, and 367.19 to 121.24, respectively. The method was validated for cortisol and cortisone determination over a concentration range of 0.5–50 ng/mL The detection limits for cortisol and cortisone in human sweat were 0.3 and 0.2 ng/ml, respectively. The interday coefficients of variation of cortisol and cortisone were ≤8.5% and ≤10.01%, whereas bias was in the range from −7.9% to 2.1% and from −4.3% to 3.0%, respectively. The assay was successfully applied to evaluate the cortisol-to-cortisone ratio in sweat samples collected from healthy adult volunteers.

Molecularly imprinted Monolithic column-based SERS sensor for selective detection of cortisol in dog saliva

Molecularly imprinted monolithic column embedded with silver nanoparticles (MIMC@Ag) was synthesized by in-situ polymerization with template and porogen inside capillary tube followed by silver precursor reduction and template/porogen removal for realizing Raman detection of cortisol. Dense silver nanoparticles generated within the monolith makes this kind of column suitable for surface enhanced Raman scattering (SERS) detection, designated as SERS-MIMC. Scanning electron microscopy and BET profiler confirmed larger pore structure in the column after template removal. The corresponding increased mass transfer/binding rate, selective adsorption and adsorptive mechanism of the MIMC were well studied with a series of adsorption experiments. The minimum Raman detectable concentration of cortisol is 1 × 10^-7 mol L^-1 by using MIMC@Ag with a good linear relationship in the concentration range from 1 × 10^-3 to 1 × 10^-7 mol L^-1. SERS sigmal of cortisol can be clearly distinguished from its analogs (estradiol, cholesterol and dexamethasone), proving the selective recognition of cortisol for SERS detection by MIMC@Ag. This ease-to-prepare SERS-MIMC sensor also shows good stability and reusability. The SERS-MIMC has been successfully applied for the easy, sensitive and selective detection of cortisol in dog saliva.

Rapid Screening of Glucocorticoid Receptor (GR) Effectors Using Cortisol-Detecting Sensor Cells

Cortisol, a stress hormone, plays key roles in mediating stress and anti-inflammatory responses. As abnormal cortisol levels can induce various adverse effects, screening cortisol and cortisol analogues is important for monitoring stress levels and for identifying drug candidates. A novel cell-based sensing system was adopted for rapid screening of cortisol and its functional analogues under complex cellular regulation. We used glucocorticoid receptor (GR) fused to a split intein which reconstituted with the counterpart to trigger conditional protein splicing (CPS) in the presence of targets. CPS generates functional signal peptides which promptly translocate the fluorescent cargo. The sensor cells exhibited exceptional performance in discriminating between the functional and structural analogues of cortisol with improved sensitivity. Essential oil extracts with stress relief activity were screened using the sensor cells to identify GR effectors. The sensor cells responded to peppermint oil, and L-limonene and L-menthol were identified as potential GR effectors from the major components of peppermint oil. Further analysis indicated L-limonene as a selective GR agonist (SEGRA) which is a potential anti-inflammatory agent as it attenuates proinflammatory responses without causing notable adverse effects of GR agonists.

Aptamer-Based Lateral Flow Biosensor for Rapid Detection of Salivary Cortisol

We have developed a disposable point-of-care (POC) aptamer-based biosensor for the detection of salivary cortisol. Nonstressful and noninvasive sampling of saliva compared to that of blood makes saliva an attractive biological matrix in developing POC devices for biomarker monitoring. Aptamers are attractive as recognition elements for multiple reasons, including their specific chemical synthesis, high stability, lack of immunogenicity, and cell-free evolution. A duplex aptamer conjugated to the surface of Au nanoparticles (AuNPs) by Au-S bonds is utilized as the sensor probe in a lateral flow assay (LFA) device. The addition of saliva samples containing cortisol makes the cortisol-aptamer undergo conformational changes and dissociate from the capture probe. Increasing cortisol concentration in the dispensed saliva sample results in increased dissociation and leads to increased binding of AuNP conjugate on the test line. Therefore, the color intensity of the test line on the LFA is a direct function of the concentration of cortisol in saliva. This simple and fast method provides detection in the cortisol range of ∼0.5-15 ng/mL, which is in the clinically accepted range for salivary cortisol. The limit of detection was 0.37 ng/mL, and the accuracy was confirmed by enzyme-linked immunosorbent assay (ELISA) testing results. High selectivity was observed for salivary cortisol against other closely related steroids and stress biomarkers present in saliva.

Soft, skin-interfaced microfluidic systems with integrated immunoassays, fluorometric sensors, and impedance measurement capabilities

Soft microfluidic systems that capture, store, and perform biomarker analysis of microliter volumes of sweat, in situ, as it emerges from the surface of the skin, represent an emerging class of wearable technology with powerful capabilities that complement those of traditional biophysical sensing devices. Recent work establishes applications in the real-time characterization of sweat dynamics and sweat chemistry in the context of sports performance and healthcare diagnostics. This paper presents a collection of advances in biochemical sensors and microfluidic designs that support multimodal operation in the monitoring of physiological signatures directly correlated to physical and mental stresses. These wireless, battery-free, skin-interfaced devices combine lateral flow immunoassays for cortisol, fluorometric assays for glucose and ascorbic acid (vitamin C), and digital tracking of skin galvanic responses. Systematic benchtop evaluations and field studies on human subjects highlight the key features of this platform for the continuous, noninvasive monitoring of biochemical and biophysical correlates of the stress state.

Carbon fiber based electrochemical sensor for sweat cortisol measurement

This study examines the use of a conductive carbon fiber to construct a flexible biosensing platform for monitoring biomarkers in sweat. Cortisol was chosen as a model analyte. Functionalization of the conductive carbon yarn (CCY) with ellipsoidal Fe₂O₃ has been performed to immobilize the antibodies specific to cortisol. 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-Hydroxysuccinimide (NHS) chemistry has been used to immobilize the antibodies onto the Fe₂O₃ modified CCY. Crystallinity, structure, morphology, flexibility, surface area, and elemental analysis were studied using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, Field emission scanning electron microscopy with energy dispersive X-ray spectroscopy (FE-SEM/EDS) and Brunauer–Emmett–Teller (BET) analysis. Mechanical properties of the fiber such as tensile strength, young’s modulus have also been investigated. Under optimal parameters, the fabric sensor exhibited a good linearity (r² = 0.998) for wide a linear range from 1 fg to 1 μg with a detection limit of 0.005 fg/mL for the sensitive detection of cortisol. Repeatability, reliability, reproducibility, and anti-interference properties of the current sensor have been investigated. Detection of cortisol levels in human sweat samples has also been investigated and the results were validated with commercial chemiluminescence immunoassay (CLIA) method.

Salivary cortisol and cortisone in the clinical setting

PURPOSE OF REVIEW

A resurgence of interest in salivary biomarkers has generated evidence for their value in assessing adrenal function. The advantages of salivary measurements include only free hormone is detected, samples can be collected during normal daily routines and stress-induced cortisol release is less likely to occur than during venepuncture. We review the use of salivary biomarkers to diagnose and monitor patients for conditions of cortisol excess and deficiency and discuss the value of measuring salivary cortisone versus salivary cortisol.

RECENT FINDINGS

Developments in laboratory techniques have enabled the measurement of salivary hormones with a high level of sensitivity and specificity. In states of altered cortisol binding, salivary biomarkers are more accurate measures of adrenal reserve than serum cortisol. Salivary cortisone is a superior marker of serum cortisol compared with salivary cortisol, specifically when serum cortisol is low and during hydrocortisone therapy when contamination of saliva may result in misleading salivary cortisol concentrations.

SUMMARY

Salivary cortisol and cortisone can be used to assess cortisol excess, deficiency and hydrocortisone replacement, with salivary cortisone having the advantage of detection when serum cortisol levels are low and there is no interference from oral hydrocortisone.

Correlation between Serum IgE and Salivary Cortisol Levels in Subjects with Type I Allergic Disorders

This study compares the relationship between serum IgE and salivary Cortisol levels in 42 normal and in 18 type I allergic subjects. Levels of serum total IgE and salivary Cortisol were determined with the UniCAP system and ELISA respectively. In the type I allergic subjects, there was a significant correlation between serum IgE and salivary Cortisol levels ( p < 0.01). In the normal subjects, on the other hand, no correlation was found. These findings suggest that there may be an association between stress and allergic disorders.

Electrochemical sensing of cortisol: a recent update

Psychological stress caused by everyday lifestyle contributes to health disparities experienced by individuals. It affects many biomarkers, but cortisol - "a steroid hormone" - is known as a potential biomarker for psychological stress detection. Abnormal levels of cortisol are indicative of conditions such as Cushing's syndrome Addison's disease, adrenal insufficiencies and more recently post-traumatic stress disorder (PTSD). Chromatographic techniques, which are traditionally used to detect cortisol, are a complex system requiring multistep extraction/purification. This limits its application for point-of-care (POC) detection of cortisol. However, electrochemical immunosensing of cortisol is a recent advancement towards POC application. This review highlights simple, low-cost, and label-free electrochemical immunosensing platforms which have been developed recently for sensitive and selective detection of cortisol in bio-fluids. Electrochemical detection is utilized for the detection of cortisol using Anti-Cortisol antibodies (Anti-Cab) covalently immobilized on nanostructures, such as self-assembled monolayer (SAM) and polymer composite, for POC integration of sensors. The observed information can be used as a prototype to understand behavioral changes in humans such as farmers and firefighters. Keeping the future directions and challenges in mind, the focus of the BioMEMS and Microsystems Research Group at Florida International University is on development of POC devices for immunosensing, integration of these devices with microfluidics, cross validation with existing technologies, and analysis of real sample.

A comparison of capillary, venous, and salivary cortisol sampling after intense exercise

Venipuncture is expensive, invasive, and impractical for many sport-science and clinical-based settings. Salivary free cortisol is often cited as a noninvasive practical alternative. However, when cortisol concentrations exceed the corticosteroid-binding globulin (CBG) point of 500 nmol/L, a lack of agreement between salivary and venous blood cortisol has been found. Alternatively, capillary blood may present a minimally invasive, cost-effective, and practical surrogate for determining cortisol concentration.

PURPOSE

The aim of this study was to determine whether cortisol concentrations sampled from capillary blood and saliva accurately reflect those found in venous blood across a large range of concentrations after intense exercise.

METHODS

Eleven healthy aerobically trained male subjects were recruited. Capillary, salivary, and venous blood samples were collected before and after (immediately and 5, 10, 15, and 20 min after) a treadmill VO(2) max test.

RESULTS

Capillary and venous concentrations increased at a similar rate after exercise (Cohen d.14-.33), increasing up to 15 min postexercise before a decline was seen. Salivary cortisol values increased at a slower rate than venous and capillary cortisol but continued to increase 15 min postexercise (Cohen d .19-.47 and .09-.72, respectively).

CONCLUSIONS

Capillary cortisol accurately reflects concentrations assayed from venous blood across a range of values below and above the CBG binding point. Capillary sampling provides a minimally invasive, cost-effective, practical surrogate for assessment of hypothalamic-pituitary-gland function.

Recent advances in cortisol sensing technologies for point-of-care application

Everyday lifestyle related issues are the main cause of psychological stress, which contributes to health disparities experienced by individuals. Prolonged exposure to stress leads to the activation of signaling pathways from the brain that leads to release of cortisol from the adrenal cortex. Various biomarkers have been affected by psychological stress, but cortisol "a steroid hormone" is known as a potential biomarker for its estimation. Cortisol can also be used as a target analyte marker to determine the effect of exposure such as organophosphates on central nervous system, which alters the endocrine system, leading to imbalance in cortisol secretion. Cortisol secretion of individuals depends on day-night cycle and field environment hence its detection at point-of-care (POC) is deemed essential to provide personalized healthcare. Chromatographic techniques have been traditionally used to detect cortisol. The issues relating to assay formation, system complexity, and multistep extraction/purification limits its application in the field. In order to overcome these issues and to make portable and effective miniaturized platform, various immunoassays sensing strategies are being explored. However, electrochemical immunosensing of cortisol is considered as a recent advancement towards POC application. Highly sensitive, label-free and selective cortisol immunosensor based on microelectrodes are being integrated with the microfluidic system for automated diurnal cortisol monitoring useful for personalized healthcare. Although the reported sensing devices for cortisol detection may have a great scope to improve portability, electronic designing, performance of the integrated sensor, data safety and lifetime for point-of-care applications, This review is an attempt to describe the various cortisol sensing platforms and their potential to be integrated into a wearable system for online and continuous monitoring of cortisol rhythm at POC as a function of one's environment.

Associations between chronotype and salivary endocrinological stress markers

OBJECTIVES

To investigate the effect of chronotype on salivary cortisol or salivary α-amylase (sAA).

METHODS

From 108 male university students, saliva samples were collected in the afternoon (between 15:00 and 17:00). The salivary cortisol and sAA levels were determined with commercial kits. Chronotype was quantitatively evaluated using the Horne and Östberg Morningness-Eveningness Questionnaire. Subjects were categorized into morning types and evening types.

RESULTS

The sAA levels were lower in the morning types than in the evening types. We found no significant difference in salivary cortisol levels between the two groups.

CONCLUSIONS

These findings suggest that the sAA levels may be associated with chronotype.

Effects of woodland walking on salivary stress markers cortisol and chromogranin A

OBJECTIVE

We investigated the effect of walking through woodland on salivary endocrinological stress markers, cortisol and chromogranin A (CgA).

DESIGN

From 20 healthy males, saliva samples were collected immediately before and after the walk, and 20min and 40min after that. In addition, using visual analog scales, subjective perceptions of stress and of feeling tired and uplifted were evaluated. On another day, as a control, they sat around in their office and samples were collected at the same times. Salivary cortisol and CgA levels were determined by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Samples taken after the walk showed a significant increase in the levels of CgA. Meanwhile, there was no significant change in the levels of cortisol. In control samples, there was a statistically significant decrease in the levels of both CgA and cortisol. Feelings uplifted and tired increased and subjective perception of stress decreased significantly after the walk. During the control period, there were no such changes.

CONCLUSION

These findings suggest that, while walking in woodland becomes a physical stressor, such activity may also bring about feeling uplifted.

Effect of snack eating on sensitive salivary stress markers cortisol and chromogranin A

OBJECTIVES

To investigate the effect of snack eating on salivary cortisol and chromogranin A (CgA).

METHODS

From 14∶00 to 18∶00, starting two hours after consumption of a midday meal, saliva samples were collected every 30 minutes from 15 healthy males, 7 of whom (snack group) ate a snack immediately after the sampling at 15∶00. Salivary cortisol and CgA levels were determined by ELISA. Samples were controlled according to salivary flow rates.

RESULTS

For the snack group, after snack consumption, salivary cortisol increased to exceed significance (p<0.05) at 15∶30 and rose even higher at 16∶00. In the control group, there was no such change. There was no significant change in salivary CgA in either the snack group or the control groups during the sampling period.

CONCLUSIONS

These findings suggest that no food should be consumed for at least 90 mins before saliva sampling for cortisol determination and that salivary CgA is probably not affected by snack eating.

Lifestyle, mental health status and salivary secretion rates

The relations between salivary variables, lifestyle and mental health status were investigated for 61 healthy female university students. The salivary secretion rates were significantly higher in the good lifestyle groups compared with the poor lifestyle groups. Among the 8 lifestyle items tested. "eating breakfast" and "mental stress" were significantly related to the salivary secretion rates. The present findings suggest that the acquisition of a good lifestyle is also very important from the viewpoint of the prevention of oral disease.A highly significant correlation (r=0.97; p<0.01) between the salivary cortisol levels and the cortisol secretion rates when controlled for the salivary secretion rates was also observed. This suggests that there is a high correlation between the intact salivary cortisol levels and the total cortisol quantity per unit time. Therefore, both these values can be used as a good index for the salivary cortisol determination.

Differences in salivary alpha-amylase and cortisol responsiveness following exposure to electrical stimulation versus the Trier Social Stress Tests

Background

Cortisol is an essential hormone in the regulation of the stress response along the HPA axis, and salivary cortisol has been used as a measure of free circulating cortisol levels. Recently, salivary alpha-amylase (sAA) has also emerged as a novel biomarker for psychosocial stress responsiveness within the sympathetic adrenomedullary (SAM) system.

Principal Findings

We measured sAA and salivary cortisol in healthy volunteers after exposure to the Trier Social Stress Test (TSST) and electric stimulation stress. One hundred forty-nine healthy volunteers participated in this study. All subjects were exposed to both the TSST and electric stimulation stress on separate days. We measured sAA and salivary cortisol levels three times immediately before, immediately after, and 20 min after the stress challenge. The State (STAI-S) and Trait (STAI-T) versions of the Spielberger Anxiety Inventory test and the Profile of Mood State (POMS) tests were administered to participants before the electrical stimulation and TSST protocols. We also measured HF, LF and LF/HF Heart Rate Variability ratio immediately after electrical stimulation and TSST exposure. Following TSST exposure or electrical stimulation, sAA levels displayed a rapid increase and recovery, returning to baseline levels 20 min after the stress challenge. Salivary cortisol responses showed a delayed increase, which remained significantly elevated from baseline levels 20 min after the stress challenge. Analyses revealed no differences between men and women with regard to their sAA response to the challenges (TSST or electric stimulations), while we found significantly higher salivary cortisol responses to the TSST in females. We also found that younger subjects tended to display higher sAA activity. Salivary cortisol levels were significantly correlated with the strength of the applied electrical stimulation.

Conclusions

These preliminary results suggest that the HPA axis (but not the SAM system) may show differential response patterns to distinct kinds of stressors.

The effects of circadian rhythmicity of salivary cortisol and testosterone on maximal isometric force, maximal dynamic force, and power output

The study investigated the effects of circadian rhythm of cortisol (C) and testosterone (T) on maximal force production (Fpeak) and power output (Ppeak). Twenty male university students (mean age = 23.8 ± 3.6 years, height = 177.5 ± 6.4 cm, weight = 78.9 ± 11.2 kg) performed 4 time-of-day testing sessions consisting of countermovement jumps (CMJs), squat jumps (SJ), isometric midthigh pulls (IMTPs), and a 1-repetition maximum (1RM) squat. Saliva samples were collected at 0800, 1200, 1600, and 2000 hours to assess T and C levels on each testing day. Session rate-of-perceived exertion (RPE) scores were collected after each session. The results showed that Fpeak and Ppeak presented a clear circadian rhythm in CMJ and IMTP but not in SJ. One repetition maximum squat did not display a clear circadian rhythm. Session RPE scores collected at 0800 and 2000 hours were significantly (p ≤ 0.05) higher than those obtained at 1200 and 1600 hours. Salivary T and C displayed a clear circadian rhythm with highest values at 0800 hours and lowest at 2000 hours; however, no significant correlation was found between T and C with Fpeak and Ppeak. A very strong correlation was found between Taural with Fpeak of CMJ and IMTP and Ppeak of CMJ (r = 0.86, r = 0.84 and r = 0.8, p ≤ 0.001). The study showed the existence of a circadian rhythm in Fpeak and Ppeak in CMJ and IMTP. The evidence suggests that strength and power training or testing should be scheduled later during the day. The use of Taural seemed to be a more effective indicator of physical performance than hormonal measures, and the use of session RPE should also be closely monitored because it may present a circadian rhythm.

Differential susceptibility to long-term effects of quality of child care on externalizing behavior in adolescence?

Much research on the quality of child care reveals it —in the case of low-quality child care—to be related to poorer child functioning, net of confounding factors, perhaps especially in the case of cognitive-linguistic performance. Recent work using data from the National Institute of Child Health and Human Development (NICHD) Study of Early Child Care and Youth Development (USA) makes clear that when children’s early negative emotionality/difficult temperament is taken into account, it also predicts externalizing problems reported by teachers through the primary school years. More negatively emotional infants are more affected—for better and for worse—by child care quality than less difficult ones, such that the latter appear unaffected by it but the former benefit from good quality care and are adversely affected by poor quality care. Here we determine whether the same is true when children are restudied in adolescence and the focus is their own reports of externalizing problems, impulsivity and risk taking. Results prove more consistent with a diathesis-stress model of environmental action than a differential-susceptibility-related one, in that 15-year-olds who were highly negative as infants report more externalizing behavior (but not risk taking or impulsivity) if they experienced low-quality child care, but not fewer problems if they experienced high-quality care relative to their counterparts with less difficult temperaments in infancy. Results are discussed in relation to physiological stress, with possible explanations offered as to why the predictive nature of child care experience might change over time.

Change of salivary stress marker concentrations during pregnancy: maternal depressive status suppress changes of those levels

AIM

The aim of the present study was to show changes in salivary cortisol and chromogranin A/protein concentrations as stress markers during pregnancy and to clarify the effect of chronic stress on stress markers.

MATERIAL AND METHODS

Salivary samples were collected from 69 pregnant women during pregnancy. Salivary cortisol levels and chromogranin A/protein titers were determined. We surveyed the women's chronic stress using the Zung self-rating depression scale and General Health Questionnaire-28.

RESULTS

Cortisol levels in the saliva of pregnant women showed biphasic change during pregnancy. Chromogranin A/protein levels in the saliva of pregnant women increased in the second and the early third trimesters and decreased to the puerperal period. Salivary cortisol concentrations of the chronic high stress group were significantly lower compared with those of the normal group. Salivary chromogranin A/protein concentrations of the chronic high stress group were also significantly lower than those of the normal group.

CONCLUSION

The titration of salivary cortisol concentrations and chromogranin A/protein levels is a useful tool to determine maternal stress levels. The elevation of cortisol and chromogranin A/protein in the saliva was suppressed in the chronic high stress group during pregnancy.

Stress hormone levels in saliva after shogi competition are modified by stress coping strategies

OBJECTIVE

Using shogi, a representative table game popular in Japan, to model a stress situation, we investigated the modulatory effects of player characteristics on changes in the levels of cortisol and testosterone in the saliva of the players.

METHODS

Saliva samples were collected at the following time-points: (1) 30 min after awakening on the day of the shogi convention; (2) immediately before the game; (3) immediately after the game; (4) 30 min after the end of game; (5) 30 min after awakening the following morning. The study cohort comprised 90 healthy male university students who were members of a shogi club, who were subsequently classified into either the emotional strategy (Em) or cognitive strategy (Co) group based on their scores on a Lazarus-type stress coping inventory.

RESULTS

Cortisol levels were significantly higher in the Em group than in the Co group the morning following the convention, and this difference was not affected by either outcome (victory or defeat) or perception (competitive or noncompetitive) of the match. A similar but non-significant trend was observed for testosterone levels.

CONCLUSION

Our findings suggest that the Em group had a greater capacity to manage the stress from a shogi convention than the Co group.

Elevated salivary α-amylase and cortisol levels in unremitted and remitted depressed patients

Abstract Objective. Major depressive disorder (MDD) is often associated with dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis via chronic stress. Psychosocial stress-induced activation of salivary α-amylase (sAA) represents sympathoadrenal medullary system (SAM) activity, and sAA has become an emerging biomarker for sympathetic nervous system activity. In contrast to salivary cortisol, sAA has been less extensively studied in depressed patients. The present study sought to address this problem by measuring sAA and salivary cortisol levels in patients with major depressive disorder. Methods. The authors recorded Spielberger State-Trait Anxiety Inventory (STAI) scores along with, levels of sAA and salivary cortisol in 28 patients with unremitted major depressive disorder, 43 remitted patients and 103 healthy volunteers. Results. STAI (State or Trait) measurements in unremitted patients with MDD were significantly increased compared with healthy controls and remitted patients. SAA and cortisol levels in unremitted patients were also significantly elevated compared to controls and remitted patients. Finally, sAA levels were significantly correlated with HRSD in unremitted patients with MDD. Conclusion. These preliminary results suggest that sAA may be a state-dependent marker of major depressive disorder in addition to salivary cortisol.

Perceived and physiological arousal during a stress task: can they differentiate between anxiety and depression?

BACKGROUND

Anxiety and depression might be two different valid constructs that often co-occur, or they could be different manifestations of the same underlying vulnerability. A theoretical framework to address this question is the tripartite model, by Clark and Watson, which hypothesizes that physiological hyperarousal (PH) is specific for anxiety. Knowledge about the relationship between PH, psychophysiological measures, perceived arousal, and anxiety would increase our understanding of the validity of the PH construct in this model. Our objective was to assess whether (a) hypothalamic-pituitary-adrenocortical (HPA) axis functioning, and (b) perceived arousal before, during and after stress can differentiate anxious from depressive children.

METHODS

In a general population sample of 225 children aged 8-12 years, self-reported anxiety and depressive symptoms were assessed using the Multidimensional Anxiety Scale for Children (MASC) and the Children's Depression Inventory (CDI). Perceived arousal was assessed using a self-report questionnaire before, during and after a stress task. Basal and reactive HPA-axis functioning were used as indices for psychophysiological arousal.

RESULTS

Our data showed that the relation between perceived arousal and anxiety problems is stronger than the relation with depressive problems. Reactive HPA-axis functioning is reduced in children with depressive problems.

CONCLUSIONS

Some evidence was found in support of the tripartite model. Our findings indicate that perceived arousal to a challenge might be a useful tool to assess the PH component of the tripartite model. Reactive HPA-axis functioning might be able to differentiate between anxiety and depressive problems in children in a general population sample, but effect sizes are small and replication is needed.

Salivary biosensors for screening trauma-related psychopathology

After facial trauma, a distinct subset of patients goes on to develop mental health problems including recalcitrant psychopathology. Early identification of maladaptive stress reactions provides opportunities for initiating preemptive mental health interventions and hinges on the surgeon's ability to differentiate between transient distress and precursors of recalcitrant psychiatric sequelae. The comprehensive care of injured patients will benefit greatly from objective adjuncts and decision-making tools to complement the clinical evaluation. This article addresses meeting the need for practical, standardized, and reliable screening strategies through promising developments in the use of stress response biomarkers and biosensing technology. The systematic interrogation of differentially expressed stress response biomarkers in saliva now permits rapid assessment of the psychopathogical response to the stressor. Quantitative, point-of-use measurements of the traumatic stress response will greatly improve the nosology of posttraumatic stress disorders and help advance the screening, diagnosis, treatment, and prevention of mental health consequences of violence and trauma.

Effects of habitual alcohol intake on ambulatory blood pressure, heart rate, and its variability among Japanese men

We sought to examine effects of habitual alcohol intake on ambulatory blood pressure (BP), heart rate (HR), and HR variability among Japanese men. Subjects were 539 men aged 35 to 65 years from rural and urban communities. Ambulatory BP and HR were monitored with an automated, portable, noninvasive multibiomedical recorder. Power spectral analysis of the RR intervals on the ECG was performed every 5 minutes. Compared with nondrinkers, moderate drinkers (alcohol intake 23 to 45 g/d) and heavy drinkers (alcohol intake >or=46 g/d) showed higher age- and field-adjusted mean values of systolic and diastolic BPs during the morning and while awake, but there were no differences in BPs over 24-hour periods and while asleep among the alcohol intake categories. Alcohol intake was positively associated with mean values of sleep-morning differences and daytime variability in BPs, HRs while awake and asleep, and low frequency:high frequency ratio while asleep. The results were virtually unchanged after adjustment for body mass index, smoking, and diabetes mellitus. Compared with the nondrinkers, age- and field-adjusted odds ratios of the morning BP surge (excess elevation of BP in the morning: morning systolic BP minus sleep systolic BP >or=37 mm Hg) for light (alcohol intake 0 to 22 g/d), moderate, and heavy drinkers were 0.96 (95% CI: 0.34 to 2.78), 1.68 (95% CI: 0.64 to 4.38), and 2.73 (95% CI: 1.12 to 6.67), respectively. Habitual alcohol intake was associated with increased BP in the morning, HR while awake and asleep, and sympathetic activity while asleep, which may explain some of the mechanisms of the relationship between heavy alcohol intake and risk of cardiovascular diseases.

Effect of lavender aroma on salivary endocrinological stress markers

OBJECTIVE

We evaluated the stress relief effect of lavender aroma by measuring sensitive salivary endocrinological stress markers, cortisol and chromogranin A (CgA).

DESIGN

Thirty healthy students performed a serial arithmetic task for 10min and then rested for 10min. During the resting period, 16 students (aroma group) were exposed to airborne organic essential oil of lavender. Saliva samples were collected immediately before and after the arithmetic task, and at 5 and 10min after that. Salivary cortisol and CgA levels were determined by enzyme-linked immunosorbent assay.

RESULTS

In the aroma group, levels of CgA that had been elevated at the end of the arithmetic task were statistically significantly lower 10min later. The control group showed no such change. During the protocol, no statistically significant changes in levels of cortisol were detected in either the aroma group or the control group.

CONCLUSIONS

These findings suggest that lavender aroma has a stress relief effect.

HEALTH-RELATED LIFESTYLE AND PATTERNS OF BEHAVIOR RELATED TO HEALTH EFFECTS OF LEISURE TRAVEL

Whether or not leisure travel might have positive effects on personal health was investigated. During a short leisure trip, saliva samples were collected from 40 females. Levels of salivary cortisol and chromogranin A (CgA) were evaluated by enzyme-linked immunosorbent assay (ELISA). To quantitatively evaluate the health-related lifestyle and the patterns of behavior of the subjects, we also administered written questionnaires. For samples taken during the trip, there was a significant increase in the levels of CgA. Meanwhile, there was a significant increase in the levels of cortisol after the tour. These tendencies were more pronounced in individuals who scored well for health-related lifestyle. These findings suggest that the effects of travel were more beneficial for persons with positive characteristics related to health-related lifestyle.

Oral treatment with L-lysine and L-arginine reduces anxiety and basal cortisol levels in healthy humans

Dietary supplementation with an essential amino acid L-lysine has been shown to reduce chronic anxiety in humans with low dietary intake of L-lysine. A combination of L-lysine and L-arginine has been documented to normalize hormonal stress responses in humans with high trait anxiety. The present study was carried out in one hundred eight healthy Japanese adults. The aim of study was to find out whether a week-long oral treatment with L-lysine (2.64 g per day) and L-arginine (2.64 g per day) reduces trait and stress-induced state anxiety and basal levels of stress hormones. We confirmed that, without regard to gender, the amino acid treatment significantly reduced both trait anxiety and state anxiety induced by cognitive stress battery. In addition, we found that the treatment with L-lysine and L-arginine decreased the basal levels of salivary cortisol and chromogranin-A (a salivary marker of the sympatho-adrenal system) in male subjects. These results of this double-blind, placebo controlled and randomized study confirm the previous findings in humans and animals and point to a combination of L-lysine and L-arginine as a potentially useful dietary intervention in otherwise healthy humans with high subjective levels of mental stress and anxiety.

Daycare attendance, stress, and mental health

OBJECTIVE

Daycare stress can be indexed by cortisol, and elevated levels of cortisol have been implicated in the onset and development of mental health disorders. Our objective was to quantify the associations between daycare and cortisol and to identify individual and environmental conditions under which daycare attendance is associated with cortisol concentrations.

METHODS

We used Cohen effect size statistics to quantify these associations and to compare them across 11 published studies that were identified with MEDLINE and PsycINFO.

RESULTS

Cortisol levels increased during the daycare day, whereas they decreased when children stayed at home. The mean effect size was d = 0.72. The magnitude of the daycare-stress relation seemed to vary under 3 specific conditions. First, the effect size was larger for children in low-quality daycare (d = 1.15), whereas there was essentially little or no effect for children in high-quality daycare (d = 0.10). Second, the effect size was larger for preschoolers (aged 39 to 59 months) (d = 1.17) than for infants (aged 3 to 16 months) (d = 0.11) or school-aged children (aged 84 to 106 months) (d = 0.09). Third, children with difficult temperaments in daycare were more likely to exhibit a rising pattern of cortisol, compared with children who were not difficult.

CONCLUSIONS

Our review suggests that daycare attendance in relatively low-quality daycare conditions and for children with difficult temperaments may result in atypical cortisol elevation. Although the link between atypical cortisol elevation and mental health requires further study, programs aimed at improving the quality of daycare services during the preschool years are expected to lead to better physiological adaptation to daycare and to reduce the risks of mental health problems.

Change in salivary physiological stress markers by spa bathing

We assessed the stress relief effect of spa bathing by measuring sensitive salivary stress markers, cortisol and chromogranin A (CgA). From 12 healthy males, saliva samples were collected immediately before and after spa bathing, and 30 min after that. Salivary cortisol and CgA levels were determined by ELISA. Salivary cortisol levels decreased after spa bathing. This tendency was more pronounced in individuals with higher levels of stress. The high-stress group showed lower salivary CgA levels after spa bathing, while the low-stress group higher salivary CgA levels in the same condition. These findings suggest that the spa bathing has a moderate affect on the stress relief.

Aged garlic extract prevents a decline of NK cell number and activity in patients with advanced cancer

Aged garlic extract (AGE) has manifold biological activities including immunomodulative and antioxidative effects. It is used as a major component of nonprescription tonics and cold-prevention medicines or dietary supplements. Advanced-cancer patients decline in immune functions and quality of life (QOL). The study's subjects were patients with inoperable colorectal, liver, or pancreatic cancer. In a randomized double-blind trial, AGE was administered to one group and a placebo was administered to another for 6 mo. The primary endpoint was a QOL questionnaire based on the Functional Assessment of Cancer Therapy (FACT). The subendpoints were changes in the natural-killer (NK) cell activity the salivary cortisol level from before and after administering AGE. Out of 55 patients invited to participate in the trial, 50 (91%) consented to enroll. They consisted of 42 patients with liver cancer (84%), 7 patients with pancreatic cancer (14%), and 1 patient with colon cancer (2%). Drug compliance was relatively good in both the AGE and placebo groups. Although no difference was observed in QOL, both the number of NK cells and the NK cell activity increased significantly in the AGE group. No adverse effect was observed in either group. The study showed that administering AGE to patients with advanced cancer of the digestive system improved NK cell activity, but caused no improvement in QOL.

Effects of glucocorticoids on the hypothalamic-pituitary-adrenal axis in children and adults

Inhaled and intranasal corticosteroids are widely used as effective, first-line treatments for asthma and allergic rhinitis. Despite a good safety profile of these formulations, there is increasing concern about their propensity to produce systemic adverse effects. Suppression of the hypothalamic-pituitary-adrenal axis is one of the most important potential complications. This article reviews the effects of inhaled and intranasal corticosteroids on the hypothalamic-pituitary-adrenal axis function in adults and children.

Salivary cortisol determined by enzyme immunoassay is preferable to serum total cortisol for assessment of dynamic hypothalamic--pituitary--adrenal axis activity

OBJECTIVE

The aim of this study was to determine whether salivary cortisol measured by a simple enzyme immunoassay (EIA) could be used as a surrogate for serum total cortisol in response to rapid changes and across a wide range of concentrations.

DESIGN

Comparisons of matched salivary and serum samples in response to dynamic hypothalamic-pituitary-adrenal (HPA) axis testing. Subjects Healthy women (n=10; three taking oral oestrogens) and men (n=2), aged 23--65 years, were recruited from the community. Measurements Paired saliva and serum samples were obtained during three protocols: 10 min of exercise at 90% of maximal heart rate (n=8), intravenous administration of corticotrophin-releasing hormone (CRH; n=4), and dexamethasone suppression (n=7). Cortisol was measured in saliva using a commercial high-sensitivity EIA and total cortisol was measured in serum with a commercial radioimmunoassay (RIA). Results The time course of the salivary cortisol response to both the exercise and CRH tests paralleled that of total serum cortisol. Salivary cortisol demonstrated a significantly greater relative increase in response to the exercise and CRH stimuli (697+/- 826%vs. 209+/- 150%, P=0.04 saliva vs. serum). A disproportionately larger increase in free cortisol, compared with total, would be expected when the binding capacity of cortisol-binding globulin (CBG) is exceeded. In response to dexamethasone suppression, relative decreases in cortisol were not significantly different between the two media (-47+/- 56%vs.-84+/- 8%, P=0.13 saliva vs. serum). Although a significant linear correlation was found for all paired salivary and serum total cortisol samples (n=183 pairs, r=0.60, P<0.001), an exponential model provided a better fit (r=0.81, P<0.001). The linear correlations were strengthened when data from subjects on oral oestrogens (n=52 pairs, r=0.75, P < 0.001) were separated from those not taking oestrogens (n=131 pairs, r=0.67, P<0.001). Conclusions Salivary cortisol measured with a simple EIA can be used in place of serum total cortisol in physiological research protocols. Evidence that salivary measures represent the biologically active, free fraction of cortisol includes: (1) the greater relative increase in salivary cortisol in response to tests that raise the absolute cortisol concentration above the saturation point of CBG; (2) the strong exponential relationship between cortisol assessed in the two media; and (3) the improved linear correlations when subjects known to have increased CBG were analysed separately. Thus, an advantage of measuring salivary cortisol rather than total serum cortisol is that it eliminates the need to account for within-subject changes or between-subject differences in CBG.

Prenatal stress and children's cortisol reaction to the first day of school

Maternal prenatal stress has been found to be related to over-activity and/or dysregulation of the HPA-system in the offspring. These effects are more readily apparent in response to novel situations. The aim of the present report was to examine whether pregnancy stress predicted HPA-axis reactions of children to the first day of school after the summer break. Children of mothers with more prenatal stress were compared to those of mothers with less stress. Habituation was studied by comparisons between the first school day and a second school day a week later. Finally, cortisol levels at school were compared to those of a weekend day. The participants were 29 mother-child pairs (20 girls and nine boys, mean age 5.31 years, SD = 0.50). The children's cortisol levels were determined in saliva. Multilevel analysis (hierarchical linear modelling) was used to analyze the data. Both prenatal cortisol and pregnancy anxiety were related to the children's cortisol levels as a reaction to the first school day. Children whose mothers had higher levels of morning cortisol during pregnancy, and more fear of bearing a handicapped child showed higher levels of cortisol on school days. In addition, the circadian rhythm of cortisol on school days appeared to have a steeper slope as compared to that of the circadian curve on a weekend day.

Interpersonal trust and social stress-induced cortisol elevation

A neuroendocrine correlate of interpersonal trust is relatively unknown. We investigated the relationship between an interpersonal trust-related personality (General Trust Scale) and cortisol elevation induced by social stress in 20 men. Spearman's rank order correlation analysis revealed a significant negative correlation between social stress-induced cortisol elevation and General Trust Scale. The present results indicate subjects with higher degrees of interpersonal trust have lower levels of neuroendocrine response to social stress.

Cortisol levels and time-discounting of monetary gain in humans

This study was conducted to examine the relationship between cortisol levels and preference to a small immediate over a larger delayed monetary reward. The degree of preference to a small immediate reward (a time-discounting rate) was investigated with an economic decision-making task in which each subject made an inter-temporal choice between (a) 10,000 yen available immediately and (b) an equal or larger amount of money after a delay of one year. The time-discounting rate was defined as [the required minimal amount of the delayed monetary gain for (b) to be preferred]-10,000/10, 000. Low cortisol levels were shown to associate with a large time-discounting rate, indicating that subjects with low cortisol levels may be impulsive in inter-temporal choice.

Medical Assessment of the Health Effects of Short Leisure Trips

Using responses to questionnaires and results of saliva samples from 40 women, the authors assessed the effects on health of participation in a short leisure trip (2 nights, 3 d) to Kyushu Island in Japan. They addressed transportation, sightseeing, and group activities during the tour, which might differ from participants' usual activities. Levels of the salivary endocrinological stress markers cortisol and chromogranin A (CgA) were determined by enzyme-linked immunosorbent assay (ELISA). In each of the groups with characteristics considered healthy and related to lifestyle, patterns of behavior, perceived stressors, and stress reactions, a decrease in the cortisol levels and an increase in the CgA levels were apparent during the tour. The baseline for stress hormone changes was the levels on awakening on Day 1 (i.e., immediately before the tour). These findings suggest that even short periods of travel can bring about a reduction in di-stress and acquisition of eu-stress, experienced as feeling uplifted or fulfilled.

Social stress-induced cortisol elevation acutely impairs social memory in humans

Although stress is known to affect the memory process, little has been elucidated regarding its effect on social memory. In this study, 30 subjects' social memory (face-name association memory) performance was tested. Twenty subjects were exposed to social stress with a subsequent test of social memory, while the remaining ten subjects served as controls. Free cortisol was determined via saliva samples taken before and after the social stress exposure. Because stress hormones might have biphasic actions on neurons, we separated the subjects with cortisol elevations between high and low responders. The high responders had significantly impaired social memory. Furthermore, we observed a negative relation between social stress-induced cortisol elevation and social memory. These results indicate that social stress acutely impairs social memory.

Effects of phototherapy in neonates on circadian sleep-wake and saliva cortisol level rhythms

The influence of phototherapy treatment during the neonatal period on sleep-wake rhythm, and its long-term effects on biological rhythms, was evaluated in preterm and full-term infants. Forty-three infants treated with phototherapy during the neonatal period and 47 untreated infants were examined for entrainment of sleep-wake rhythms between 16 and 52 weeks and for sleep-wake and saliva cortisol rhythms at 2.5 years of age. The age of sleep-wake rhythm entrainment was not significantly different between the 2 groups. No correlations between duration of exposure to phototherapy and corrected age of entrainment of sleep-wake rhythm were observed. At follow-up, no significant differences in sleep-wake and saliva cortisol rhythms were observed between the 2 groups, indicating that circadian variations were similar to those in adults.

Chronic stress in nonelderly caregivers: psychological, endocrine and immune implications

OBJECTIVE

This investigation examined whether the immune dysregulation that characterises elderly informal caregivers (e.g., spousal caregivers of dementia patients) extends to a younger caregiver population, specifically spousal carers of patients with multiple sclerosis (MS).

METHOD

MS spousal caregivers (n=41, mean age 43 years, 14 women, 27 men) and noncaregiving controls (n=62, mean age 33 years, 44 women, 18 men) were recruited. Psychological morbidity (i.e., self-reported stress, anxiety and depression), endocrine activity (i.e., salivary cortisol and DHEAs) and immunity (i.e., IgG and HAI responses to influenza vaccination and IFN-gamma and IL-4 levels) were assessed.

RESULTS AND CONCLUSIONS

MS caregivers and noncaregivers did not differ significantly in their IgG or HAI responses to influenza vaccination or in levels of IFN-gamma and IL-4. However, it remains unclear whether the "preserved" immune response of these younger caregivers was due to (1) an absence of immune senescence, (2) a relative absence of psychological morbidity, or both.

Stress hormones: how do they measure up?

Stress as a stimulus is integral to dynamic homeostatic functioning. However, evidence of its potentially deleterious effects on health is mounting. The impetus to understand the mechanisms that underlie stress-related negative health outcomes and prevent the development of stress-related disorders has never been greater. Symptom severity and subjective levels of stress, although frequently assessed in studies of stress in nursing research, may not provide adequate data to fully understand the pervasive effects of chronic or overwhelming stress associated with stress disorders. The measurement of stress hormones such as cortisol can help identify bodily changes that are stressor specific, people at risk for development of stress-related disorders, and the efficacy of interventions aimed at stress reduction. Cortisol, as the peripheral output of one of the major stress response systems, possesses several properties that make its measurement highly useful for investigations of stress. This article discusses some of the biological mechanisms involved in the stress response, why cortisol is commonly measured, and issues and approaches in cortisol measurement.