A re-investigation of saliva collection procedures that highlights the risk of potential positive interference in cortisol immunoassay

The Reliability of Salivary Cortisol Compared to Serum Cortisol for Diagnosing Adrenal Insufficiency with the Gold Standard ACTH Stimulation Test in Children

The ACTH (adrenocorticotropic hormone) stimulation test is the gold standard for the diagnosis of adrenal insufficiency (AI), performed with ACTH high dose (HDT) or low dose (LDT). As salivary cortisol has been proposed as an alternative to serum cortisol, our aim was to evaluate the reliability of salivary cortisol compared to serum cortisol for diagnosing AI in children. Data were collected retrospectively. Salivary and serum cortisol values derived by 80 ACTH stimulation tests were obtained (39 F, 36 M; median age 11.5 years, IQR 6.9). Sampling was performed at baseline and after 30 and 60 min from ACTH administration during the HDT, and at baseline and 10, 20, 30, 40 and 60 min after the stimulation for the LDT. A serum cortisol level > 420 nmol/L ruled out AI. The correlation coefficients between serum and salivary cortisol for the HDT (n = 24) were 0.80 at t0, 0.48 at t30 and 0.75 at t60. All patients were adrenal sufficient. In 41% of the LDT, peak serum cortisol indicated insufficient adrenal function. The correlation coefficients between serum and salivary cortisol were 0.59 at t0 and 0.33 at the peak. For a cut-off of salivary cortisol < 15 nmol/L, sensitivity was 73.9% and specificity 69.6%. Our data do not support salivary cortisol as a valid alternative to serum cortisol during LDT. Regarding the HDT, results are more encouraging, however, further studies are needed.

Salivary Steroid Collection in Children Under Conditions Replicating Home Sampling

CONTEXT

Measurement of salivary glucocorticoids is an accepted method for testing adrenal function but there are few data on stability during home collection. Current salivary collection techniques require active participation or present a choking hazard and are unsuitable for young children.

OBJECTIVE

We sought to compare different salivary collection methods; assess the stability of salivary glucocorticoids under conditions replicating home collection; and assess patient tolerability and caregiver acceptability of a salivary collection device for young children, a swab encased in an infant pacifier (SaliPac).

METHODS

Six healthy adults collected salivary samples using a Salivette Cortisol, passive drool, and SalivaBio at night, waking, and 3 Pm for five days. Time to collect 1-mL saliva using the SalivaBio and SaliPac and caregiver acceptability were assessed in 30 children younger than 6 years. Saliva was stored at 4 °C, room temperature (RT), and 50 °C for 24, 48, 72 hours and 1 week to replicate potential postage conditions. Salivary cortisol and cortisone concentrations were measured by mass spectrometry.

RESULTS

There was no difference in salivary glucocorticoid concentrations using the 3 collection methods. Salivary cortisol and cortisone were stable for 72 hours at RT and 4 °C, and repeated freeze-thaw cycles did not cause significant degradation. In children younger than 6 years the SalivaBio and SaliPac were well tolerated and collected sufficient saliva for salivary steroid analysis in less than 4 minutes.

CONCLUSION

Salivette, passive drool, and SalivaBio collect samples with comparable salivary cortisol and cortisone concentrations, which are stable under conditions replicating home collection. SaliPac is an acceptable device for salivary sampling in young children.

Stabilization of Salivary Biomarkers

The use of saliva as a diagnostic biofluid has been increasing in recent years, thanks to the identification and validation of new biomarkers and improvements in test accuracy, sensitivity, and precision that enable the development of new noninvasive and cost-effective devices. However, the lack of standardized methods for sample collection, treatment, and storage contribute to the overall variability and lack of reproducibility across analytical evaluations. Furthermore, the instability of salivary biomarkers after sample collection hinders their translation into commercially available technologies for noninvasive monitoring of saliva in home settings. The present review aims to highlight the status of research on the challenges of collecting and using diagnostic salivary samples, emphasizing the methodologies used to preserve relevant proteins, hormones, genomic, and transcriptomic biomarkers during sample handling and analysis.

Impact of Two Forms of Daily Preventive Zinc or Therapeutic Zinc Supplementation for Diarrhea on Hair Cortisol Concentrations Among Rural Laotian Children: A Randomized Controlled Trial

Zinc supplementation has been shown to reduce the morbidity burden among young children, and may reduce chronic stress. Hair cortisol has been promoted as an indicator of chronic stress. We assessed the impact of different strategies for delivering supplementary zinc on hair cortisol concentrations (HCC) in young Laotian children and examined risk factors associated with HCC. In a randomized double-blind controlled trial (NCT02428647), children aged 6⁻23 mo were randomized to one of four intervention groups and followed for ~36 weeks: daily preventive zinc (PZ) tablets (7 mg/day), daily multiple micronutrient powder (MNP) sachets (containing 10 mg zinc and 14 other micronutrients), therapeutic zinc (TZ) supplements for diarrhea treatment (20 mg/day for 10 days) or daily placebo powder. HCC of 512 children was assessed at baseline and endline. ANCOVA and linear regression models were used to assess group differences in HCC and to examine the risk factors associated with HCC, respectively. At enrollment, mean HCC was 28.8 ± 43.9 pg/mg. In models adjusted for age at enrollment, health district, and baseline HCC there was no overall effect of the interventions on endline HCC and change in HCC. When controlling for additional predetermined covariates, there was a marginally significant effect on change in HCC (p = 0.075) with a slightly lower reduction of HCC in TZ compared to PZ (mean change (95% CI): -4.6 (-7.0; -2.3) vs. -9.4 (-11.7; -7.0) pg/mg; p = 0.053). At baseline, consumption of iron rich foods was negatively associated with HCC, whereas AGP (α1-acid glycoprotein) levels, elevated AGP and C-reactive protein and high soluble transferrin receptor were positively associated with HCC. In young Laotian children, MNP, PZ and TZ had no impact on HCC. The marginal difference in change in HCC between the PZ and TZ groups was too small to be considered of health significance.

An experimental investigation into the extent social evaluation anxiety impairs performance in simulation-based learning environments amongst final-year undergraduate nursing students

BACKGROUND

While numerous theoretical and conceptual models suggest social evaluation anxiety would likely influence performance in simulation-based learning environments, there has been surprisingly little research to investigate the extent to which this is true.

METHODS

Final-year Bachelor of Science (Nursing) students (N=70) were randomly assigned to complete one of three clinically identical simulation-based scenarios designed to elicit varying levels of social evaluation anxiety by manipulating the number of other people present with the student during the simulation (1, 2 or 3 others). Rises in acute stress were measured via continuous heart-rate and salivary cortisol. Performance scores were derived from the average of two independent raters' using a structured clinical checklist (/16).

RESULTS

Statistically different increases were found within the first minute of the simulation between those students with one versus three other people in the room (+4.13 vs. +14.01beats-per-minute respectively, p=0.01) and salivary cortisol measures suggested significantly different changes in anxiety between these groups (-0.05 vs. +0.11μg/dL respectively, p=0.02). Independent assessments suggested students with only one other person accompanying them in the simulation significantly outperformed those accompanied by three others (12.95 vs. 10.67 respectively, p=0.03).

DISCUSSION

Students accompanied by greater numbers during simulations experienced measurably greater anxiety and measurably poorer performances. These results demonstrate the ability to manipulate social evaluation anxiety within high-fidelity simulation training of undergraduates in order to help students better acclimatise to stressful events prior to practising in real clinical settings.

Reference ranges for cortisol and α-amylase in mother and newborn saliva samples at different perinatal and postnatal periods

This paper describes a reliable analytical method based on Ultra High-Performance Liquid Chromatography coupled to tandem mass spectrometry to determine cortisol in saliva samples from healthy mothers (n=87) and newborns (n=65) at different time points: (i) 38 weeks of gestation, (ii) in the immediate postnatal period (48h) after a term delivery and, (iii) 3 months after delivery. The procedure is characterized by a simple sample treatment employing a sample volume of 25μL. In addition to this, salivary α-amylase was determined using a commercial kit. We have proposed potential reference ranges in saliva for cortisol (0.7-35nmolL(-1)) and α-amylase (2-500UmL(-1)) in mothers, and for cortisol (0.1-56nmolL(-1)) and α-amylase (0.1-500UmL(-1)) in newborn infants. In addition, statistical differences between the two sensitive population groups (mothers and newborns) at the perinatal and postnatal periods were studied. A lower concentration for maternal cortisol was found at 38 weeks of gestation than at 48h (p=0.048) or 3 months after delivery (p=0.021). Similar results were found for the α-amylase determinations. Hence, higher concentrations than could be expected from a chronic stress marker were found at 3 months after delivery than at 38 weeks of gestation (p<0.001) or 48h after delivery (p<0.001). We conclude that this analytical method could be applied to further clinical research on perinatal and postnatal stress, such as threatened preterm labor and/or parenting stress, respectively.

Saliva stimulation with glycerine and citric acid does not affect salivary cortisol levels

OBJECTIVE

In critically ill patients with hypotension, who respond poorly to fluids and vasoactive drugs, cortisol insufficiency may be suspected. In serum over 90% of cortisol is protein-bound, thus routine measures of total serum cortisol may yield 'false lows' due to hypoproteinaemia. Thus, the occurrence of cortisol insufficiency could be overestimated in critically ill patients. Salivary cortisol can be used as a surrogate for free serum cortisol, but in critically ill patients saliva production is decreased, and insufficient volume of saliva for analysis is a common problem. The aim of this study was to investigate if a cotton-tipped applicator with glycerine and citric acid could be used for saliva stimulation without affecting salivary cortisol levels.

DESIGN

Prospective, observational study.

PARTICIPANTS

Thirty-six volunteers (six males, 30 females), age 49 ± 9 years, without known oral mucus membrane rupture in the mouth.

MEASUREMENTS

Forty-two pairs of saliva samples (22 paired morning samples, 20 paired evening samples) were obtained before and after saliva stimulation with glycerine and citric acid. Salivary cortisol was analysed using Spectria Cortisol RIA (Orion Diagnostica, Finland).

RESULTS

The paired samples correlated significantly (P < 0.0001) and there was no significant difference between un-stimulated and stimulated salivary cortisol levels.

CONCLUSIONS

Saliva stimulation with a cotton-tipped applicator containing glycerine and citric acid did not significantly influence salivary cortisol levels in healthy volunteers. This indicates that salivary cortisol measurement after saliva stimulation may be a useful complement when evaluating cortisol status in critically ill patients.

Approaches to salivary cortisol collection and analysis in infants

Salivary cortisol is becoming more commonly utilized as a biologic marker of stress in observational studies and intervention research. However, its use with infants (12 months of age or younger) is less widespread and poses some special challenges to researchers. In order to decide on the most suitable collection procedure for salivary cortisol in infants, a number of criteria should be considered. This article will aid investigators interested in integrating salivary cortisol measurement into their research studies by presenting (1) an overview of the patterns of cortisol secretion in infancy including the development of diurnal rhythm and response to stress; (2) a comparison of the most commonly used approaches for collecting salivary cortisol samples in infants including cotton rope, syringe aspiration technique, filter paper, hydrocellulose microsponge, and the Salimetrics children's swab; (3) a discussion of the factors contributing to heightened cortisol variability in infancy and how these can be limited; (4) analytical issues associated with cortisol measurement; and (5) examples of criteria to consider when choosing a saliva sampling method and lab for conducting assays.

Usefulness of salivary cortisol in the diagnosis of hypercortisolism: comparison with serum and urinary cortisol

OBJECTIVE

Several tests have been proposed to diagnose patients with Cushing's syndrome (CS). The aims of the study were: i) to evaluate the performance of salivary cortisol (SC) in hypercortisolism and ii) to compare SC with serum cortisol (SeC) and urinary cortisol.

DESIGN AND PATIENTS

This was a diagnostic study. Twenty-seven patients with untreated Cushing's disease (CD untr), 21 women consuming oral contraceptive pill (OCP), 18 pregnant women, and 89 healthy subjects (controls) were enrolled.

METHODS

SC and SeC at baseline and after the low-dose dexamethasone suppression test (LDDST) and urinary free cortisol (UFC) were measured.

RESULTS

Midnight SC had a sensitivity of 100% in the CD untr group and a specificity of 97.7% in the controls. Specificity remained high (95.2%) in women taking OCP, while in pregnant women, it decreased to 83.3%. SC after the LDDST showed a sensitivity of 96.3% in the CD untr group; specificity was 97.7% in the controls and 90.5% in OCP women. Midnight SeC had a sensitivity of 100% in the CD untr group. SeC after the LDDST had a sensitivity of 100% in the CD untr group while specificity was 97.7% in the controls and 61.9% in women taking OCP. For UFC, sensitivity was 92.6% in the CD untr group while specificity was 97.7% in the controls and 100% in the OCP group.

CONCLUSIONS

SC is a reliable parameter for the diagnosis of severe hypercortisolism, with high sensitivity and specificity. In women during pregnancy or taking OCP, the measurement of SC, identifying the free fraction, could be helpful to exclude CS.

Effects of sugarless chewing gum as a stimulant on progesterone, cortisol, and testosterone concentrations assessed in saliva

Sugarless chewing gum is a frequently used stimulant to collect saliva samples for hormone analyses. This study tested the effect of sugarless chewing gum on cortisol, testosterone, and progesterone concentrations measured in saliva samples collected from 8 individuals at different times of the day (morning, evening) and under different collection conditions (gum, no gum) as well as in a saliva pool and water, either untreated or treated with chewing gum. Sugarless chewing gum raised all progesterone concentrations by 20 to 40pg/mL, corresponding to a twofold increase, relative to no-gum controls and attenuated salivary testosterone and cortisol concentrations. It is recommended that the use of sugarless chewing gum as a stimulant should be avoided with saliva samples.

Measurement of salivary cortisol in 2012 - laboratory techniques and clinical indications

The utility of measuring salivary cortisol has become increasingly appreciated since the early 1980s. Salivary cortisol is a measure of active free cortisol and follows the diurnal rhythm of serum or plasma cortisol. The saliva sample may be collected by drooling or through the use of absorbent swabs which are placed into the mouth until saturated. Salivary cortisol is therefore convenient for patients and research participants to collect noninvasively on an outpatient basis. Several assay techniques have been used to measure salivary cortisol, including radioimmunoassay and more recently liquid chromatography-tandem mass spectrometry. The analytical sensitivity varies between these assay methods, as does the potential for cross-reactivity with other steroids. The interpretation of salivary cortisol levels relies on rigorous standardization of sampling equipment, sampling protocols and assay technology with establishment of a local reference range. Clinically, the commonest use for salivary cortisol is measuring late-night salivary cortisol as a screening test for Cushing's syndrome. Several studies have shown diagnostic sensitivities and specificities of over 90%, which compares very favourably with other screening tests for Cushing's syndrome such as the 24-h urinary-free cortisol and the 1-mg overnight dexamethasone suppression test. There are emerging roles for the use of salivary cortisol in diagnosing adrenal insufficiency, particularly in conditions associated with low cortisol-binding globulin levels, and in the monitoring of glucocorticoid replacement. Finally, salivary cortisol has been used extensively as a biomarker of stress in a research setting, especially in studies examining psychological stress with repeated measurements.

Comparison of saliva collection methods in children with high-functioning autism spectrum disorders: acceptability and recovery of cortisol

This study compared cortisol concentrations yielded using three saliva collection methods (passive drool, salivette, and sorbette) in both in vitro and in vivo conditions, as well as method acceptability for a sample of children (n = 39) with High Functioning Autism Spectrum Disorders. No cortisol concentration differences were observed between passive and sorbette samples obtained in vitro or in vivo. The salivette derived concentration was lower than the other two methods for the in vitro derived comparisons but did not differ from the other methods when collected in vivo. Cross-day comparison for the salivettes was also found to differ significantly, whereas the cross-day comparisons did not differ for the passive method or the sorbette method. Overall, passive drool and sorbettes were found to produce similar and stable readings of cortisol, whereas the salivette yielded unstable and variable concentrations. Ratings suggested that the children generally perceived all methods as acceptable.

Epidemiological approaches to measure childhood stress

The prevalence of childhood stress has repeatedly been shown to be high, with 'parental separation' and 'being bullied at school' as the most frequently reported stressors in the child's everyday life. This is quite alarming as children are most vulnerable to the adverse psychological and physiological health consequences of chronic stress exposure. Despite growing research interest in this field over the last years, literature falls short in providing an overview of methods to adequately assess stress in elementary school children (6-12 years old). This review describes questionnaires and interviews, as well as laboratory measurements of cortisol in biological samples (serum, urine, saliva and hair) as stress assessment methods in children, with the emphasis on epidemiological research settings. Major characteristics, strengths and limitations of these methods are established, examples of child-specific stressor questionnaires and interviews are provided and specific recommendations with respect to epidemiological research are formulated. In addition, hair cortisol as a potential biomarker for chronic stress (in children) is discussed more thoroughly. This review is meant to serve as a preliminary guide for health researchers new to this research area by reflecting on theoretical and methodological aspects in childhood stress assessment.

Late-night salivary cortisol for diagnosis of Cushing's syndrome by liquid chromatography/tandem mass spectrometry assay

BACKGROUND

Late-night salivary cortisol (LNSC) measurements have been increasingly used by physicians as an initial diagnostic test for evaluation of patients with clinical suspicion of Cushing's syndrome (CS). Published studies include various numbers of cases, controls and importantly, various assay methods (vast majority various immunoassays), as well as various methods to generate cut-points.

MATERIALS AND METHODS

The retrospective study evaluated the diagnostic utility of LNSC measurements in 249 patients evaluated for possibility of CS because of various clinical conditions using liquid chromatography/tandem mass spectrometry method (LC-MS/MS). CS was confirmed in 47 patients (18·9%) and excluded in 202 (81·1%) patients at the time of analysis.

RESULTS

Late-night salivary cortisol was abnormal or >2·8 nmol/l in 35 of 47 patients with CS; sensitivity of 74·5% and elevated in 20 of 202 patients who were found not to have CS; specificity 90·1%. Using receiver-operator characteristic statistics for calculation of the most optimal sensitivity and specificity, the cut-off based on this data was LNSC > 2·1 nmol/l with sensitivity of 83·0% and specificity of 84·2%.

CONCLUSION

Analysis of data at one referral institution showed somewhat limited sensitivity of LNSC for diagnosis of CS using current reference ranges.

Translational research in pediatrics: tissue sampling and biobanking

Translational research is expanding and has become a focus of National Research funding agencies, touted as the primary avenue to improve health care practice. The use of human tissues for research on disease etiology is a pillar of translational research, particularly with innovations in research technologies to investigate the building blocks of disease. In pediatrics, translational research using human tissues has been hindered by the many practical and ethical considerations associated with tissue procurement from children and also by a limited population base for study, by the increasing complexities in conducting clinical research, and by a lack of dedicated child-health research funding. Given these obstacles, pediatric translational research can be enhanced by developing strategic and efficient biobanks that will provide scientists with quality tissue specimens to render accurate and reproducible research results. Indeed, tissue sampling and biobanking within pediatric academic settings has potential to impact child health by promoting bidirectional interaction between clinicians and scientists, helping to maximize research productivity, and providing a competitive edge for attracting and maintaining high-quality personnel. The authors of this review outline key issues and practical solutions to optimize pediatric tissue sampling and biobanking for translational research, activities that will ultimately reduce the burden of childhood disease.

Salivary markers of oxidative stress and Salivette collection systems

BACKGROUND

Biomarkers of oxidative stress can be measured in saliva and represent a promising tool for the research of oral diseases. Saliva sampling and further processing has been improved by Salivette collection systems. The aim of this study was to analyze the effects of two different Salivette collection systems on salivary biomarkers of oxidative stress in comparison to whole unstimulated saliva.

METHODS

Whole unstimulated saliva and saliva samples collected using cotton and polypropylene Salivette collection systems were obtained from 20 young healthy volunteers (aged 20-30 years). Advanced glycation end products (AGEs), advanced oxidation protein products (AOPP), thiobarbituric acid reacting substances (TBARS), ferric reducing ability of saliva and total antioxidant capacity were measured.

RESULTS

In samples collected using the cotton Salivette, higher AGEs and TBARS concentrations (by 97% and 2036%) were determined. In samples collected using the polypropylene Salivette cortisol, cortisol AOPP concentrations were lower (by 60%) in comparison to measurements in whole unstimulated saliva. Markers of antioxidant status were comparable in all types of samples.

CONCLUSIONS

Salivette and Salivette cortisol collection systems significantly altered the determined concentrations of several markers of oxidative stress in comparison to measurements in whole unstimulated saliva samples.

Day-to-day variations in salivary cortisol measurements

PURPOSE

The purpose of this study was to clarify the day-to-day variations of salivary cortisol to discuss the appropriate timing for collecting saliva in a day for stress evaluation.

MATERIALS AND METHODS

Saliva samples from twelve healthy adults were collected by means of Salivette(®) (SARSTEDT Co.) three times per day, immediately after awakening (Time1), 6:00 PM (Time2) and 30 min before going to bed (Time3), on 5 nonconsecutive days. Cortisol concentration was measured using a radioimmunoassay.

RESULTS

Salivary cortisol concentration showed the larger value at Time1 than that at Time2. The mean value of %CV for day-to-day variation showed the smallest value at Time1 (mean: 43.1%) and the largest value at Time3 (mean: 100.3%). There were significant differences in %CV value between Time1 and Time3, Time2 (mean: 64.1%) and Time3.

CONCLUSIONS

There are considerable day-to-day variations in salivary cortisol concentration measurements. From the viewpoint of day-to-day variation, collecting saliva immediately after awakening in the morning is thought to be more advantageous for evaluating cortisol concentration.

Steroid measurement with LC-MS/MS. Application examples in pediatrics

The correct measurement of steroids is vital for the diagnosis of congenital adrenal hyperplasia (CAH), apparent mineralocorticoid excess, familial hyperaldosteronism type I, primary aldosteronism, Cushing's disease, adrenal insufficiency, etc. Steroid diagnostics also plays an important role in disorders of sexual differentiation and gonadal function. Steroid metabolism is involved in evaluations for precocious puberty, premature thelarche, and polycystic-ovary disease. Finally, the hypothalamo-pituitary-adrenal (HPA) axis is considered to be one of the major systems involved in fetal programming or in stress regulation. Most methods for the determination of steroid hormones are based on immunoassays, which are rapid and easy to perform. However, the reliability of several steroid immunoassays has been shown to be questionable because of the lack of specificity and of matrix effects. Immunological methods, especially direct assays, often overestimate true steroid values. Patient follow-up over time or between laboratories, as well as longitudinal studies, are therefore extremely difficult. This is of particular importance in pediatrics. Liquid chromatography triple quadrupole mass spectrometry (LC-MS/MS) is an increasingly common tool in the clinical laboratory and has the potential to overcome the limitations of immunoassays. LC-MS/MS affords the specificity, imprecision, and limits of quantification necessary for the reliable measurement of steroids, expanding diagnostic capabilities. In addition to the high throughput, the method requires minimal sample preparation and a small sample volume. All these features make it an attractive method to use in a clinical setting. Moreover, LC-MS/MS has the advantage that a spectrum of steroid hormones can be measured simultaneously. Steroid profiling is a very effective method for distinguishing almost all steroid-related disorders. It allows accurate diagnosis and is very useful in many clinical situations. Steroid profiles open up new vistas. The applicability for clinical samples and questions in pediatric endocrinology will be discussed.

Steroid assays in paediatric endocrinology

Most steroid disorders of the adrenal cortex come to clinical attention in childhood and in order to investigate these problems, there are many challenges to the laboratory which need to be appreciated to a certain extent by clinicians. The analysis of sex steroids in biological fluids from neonates, over adrenarche and puberty present challenges of specificities and concentrations often in small sample sizes. Different reference ranges are also needed for interpretations. For around 40 years, quantitative assays for the steroids and their regulatory peptide hormones have been possible using immunoassay techniques. Problems are recognised and this review aims to summarise the benefits and failings of immunoassays and introduce where tandem mass spectrometry is anticipated to meet the clinical needs for steroid analysis in paediatric endocrine investigations. It is important to keep a dialogue between clinicians and the laboratory, especially when any laboratory result does not make sense in the clinical investigation.

Utility of salivary cortisol measurements in Cushing's syndrome and adrenal insufficiency

CONTEXT

The measurement of cortisol in saliva is a simple, reproducible, and reliable test to evaluate the normal and disordered control of the hypothalamic-pituitary-adrenal (HPA) axis. There are a variety of simple methods to obtain saliva samples without stress, making this a robust test applicable to many different experimental and clinical situations.

EVIDENCE ACQUISITION

Ovid Medline and PubMed from 1950 to present were searched using the following strategies: [<saliva or salivary>and<cortisol or hydrocortisone>and<Cushing or Cushing's>] and [<saliva or salivary>and<cortisol or hydrocortisone>and<adrenal insufficiency or hypoadrenalism or hypopituitarism or Addison's disease>]. The bibliographies of all relevant citations were evaluated for any additional appropriate citations.

EVIDENCE SYNTHESIS

Measurement of an elevated late-night (2300 to 2400 h) salivary cortisol has a greater than 90% sensitivity and specificity for the diagnosis of endogenous Cushing's syndrome. Late-night salivary cortisol measurements are also useful to monitor patients for remission and/or recurrence after pituitary surgery for Cushing's disease. Because it is a surrogate for plasma free cortisol, the measurement of salivary cortisol may be useful during an ACTH stimulation test in patients with increased plasma binding protein concentrations due to increased estrogen, or decreased plasma binding protein concentrations during critical illness. Most reference laboratories now offer salivary cortisol testing.

CONCLUSIONS

It is expected that the use of the measurement of salivary cortisol will become routine in the evaluation of patients with disorders of the HPA axis.