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

What is the best approach to suspected cyclical Cushing syndrome? Strategies for managing Cushing's syndrome with variable laboratory data

Cyclical Cushing's syndrome is a pattern of hypercortisolism in which the biochemistry of cortisol production fluctuates rhythmically. This syndrome is often associated with fluctuating symptoms and signs. It is now being increasingly recognized. The phenomenon is important because it can, if not recognized, lead to errors in diagnosis and differential diagnosis of the syndrome and in assessment of therapeutic outcomes. The techniques and criteria, protocols and dynamic biochemical tools to detect cycling in patients with hypercortisolism are discussed as are the strategies for diagnosing and managing this important subgroup of patients with hypercortisolism.

One-step monoclonal antibody based enzyme-linked immunosorbent assay for direct determination of cortisol in serum

Monoclonal antibodies to cortisol have obvious potential advantages as starting materials for assay systems to detect their levels in body fluids. This is very important for monitoring pituitary gland and adrenal functions. To develop a one-step competitive heterogeneous enzyme-linked immunosorbent assay (ELISA), a monoclonal anti-cortisol antibody was generated using a reasonably designed haptenic derivative. Cortisol-3-O-carboxymethyloxime was coupled to carrier protein bovine serum albumin (BSA) to enhance its immunogenicity. Spleen cells were prepared from a BALB/c mouse, which had repeatedly been immunized with a conjugate of cortisol-3-O-carboxymethyloxime-bovine serum albumin (cortisol-3-O-CMO-BSA), to be fused with SP2/0 myeloma cells. After one fusion experiment, four hybridoma clones secreting a practical antibody were established. One of the resulting monoclonal antibodies, 2C9D11B5, showed an affinity constant (Ka) of 1.4 × 10(10) M(-1) for cortisol and provided a practical calibration curve (limit of detection [LOD], 0.26 ng per assay) in this ELISA system employing cortisol-21-hemisuccinate-horseradish peroxidase (cortisol-21-HS-HRP) as a tracer. Cross-reactivities with related C-21 steroids were acceptably low: 11-deoxycortisol (3.5%), cortisone (0.47%), corticosterone (<0.01%), progesterone (<0.01%), 17-hydroxyprogesterone (1.2%), 6-hydroxycortisol (7.6%), and tetrahydrocortisol (<0.01%). The intra-assay and inter-assay coefficient of variations (CVs) ranged from 4.3% to 9.2% and 3.8% to 10.4 %, respectively. The analytical recoveries were 92.3% to 116.3%. Serum cortisol levels of healthy volunteers were determined after chilled acetone, stripped to be 292.76 ± 201.38 ng/mL (n=5), which are in the reference range.

Reliability of hypothalamic-pituitary-adrenal axis assessment methods for use in population-based studies

Population-based studies have been hampered in exploring hypothalamic-pituitary-adrenal axis (HPA) activity as a potential explanatory link between stress-related and metabolic disorders due to their lack of incorporation of reliable measures of chronic cortisol exposure. The purpose of this review is to summarize current literature on the reliability of HPA axis measures and to discuss the feasibility of performing them in population-based studies. We identified articles through PubMed using search terms related to cortisol, HPA axis, adrenal imaging, and reliability. The diurnal salivary cortisol curve (generated from multiple salivary samples from awakening to midnight) and 11 p.m. salivary cortisol had the highest between-visit reliabilities (r = 0.63-0.84 and 0.78, respectively). The cortisol awakening response and dexamethasone-suppressed cortisol had the next highest between-visit reliabilities (r = 0.33-0.67 and 0.42-0.66, respectively). Based on our own data, the inter-reader reliability (r(s)) of adrenal gland volume from non-contrast CT was 0.67-0.71 for the left and 0.47-0.70 for the right adrenal glands. While a single 8 a.m. salivary cortisol is one of the easiest measures to perform, it had the lowest between-visit reliability (R = 0.18-0.47). Based on the current literature, use of sampling multiple salivary cortisol measures across the diurnal curve (with awakening cortisol), dexamethasone-suppressed cortisol, and adrenal gland volume are measures of HPA axis tone with similar between-visit reliabilities which likely reflect chronic cortisol burden and are feasible to perform in population-based studies.

Diurnal variation of cortisol in people with dementia: relationship to cognition and illness burden

Cortisol patterns in nursing home residents with dementia are described and examined in relation to cognition and comorbid illnesses. Saliva was sampled 4 times in a 24-hour period (week 1) and at the same times 1 week later (week 2). In general, cortisol levels decreased from morning to evening, with 50% exhibiting a negative slope. In contrast, 38% of the participants had a relatively flat cortisol diurnal rhythm, and 7% exhibited an afternoon increase. The cortisol pattern was consistent between weeks 1 and 2 for 39% with a negative slope, 13% with a flat profile, and for 2% with an afternoon increase pattern. Cortisol rhythm was not statistically significantly related to cognition or illness burden. While this study contributes to the understanding of differences in the diurnal pattern of cortisol for older adults with dementia, more research is needed to understand the etiology of the differences and the biological mechanisms involved.

Corticosteroid-binding globulin regulates cortisol pharmacokinetics

OBJECTIVE

Corticosteroid-binding globulin (CBG) is the principal carrier for cortisol in the circulation. Variations in CBG-binding capacity are predicted to alter total serum cortisol disposition, but free serum cortisol is believed to be unaffected. Unbound cortisol pharmacokinetics (PK) have not been studied in the context of CBG changes. We aimed to assess the regulation of cortisol PK by CBG.

DESIGN AND SUBJECTS

Women on oestrogens [oral contraceptive pill, (OCP)], patients homozygous for a nonfunctioning CBG variant (CBG null) and healthy controls (HV) were studied before and after IV and oral administration of hydrocortisone 20 mg.

MEASUREMENTS

PK parameters were studied for total serum cortisol (SerF), free serum cortisol (FreeF) and cortisone (FreeE), and salivary cortisol (SalF) and cortisone (SalE): area under the curve (AUC), clearance (CL), half-life and volume of distribution (V(d)).

RESULTS

Following IV hydrocortisone, AUC and half-life of SerF were significantly higher in the OCP group and lower in the CBG null. SerF CL and V(d) were significantly lower in the OCP group and increased in the CBG null, compared to HV. PK parameters for FreeF and the salivary biomarkers were not different between the CBG null and HV, although OCP patients still had higher AUC compared to HV and prolonged half-life. These findings were confirmed following oral hydrocortisone, but concentration-time profiles were highly heterogeneous and SalF interpretation was problematic because of oral contamination.

CONCLUSIONS

We have demonstrated that CBG has a distinct effect on cortisol PK. When CBG binding is disrupted, FreeF retains normal PK characteristics, although CBG null patients lack a CBG-bound pool of readily releasable cortisol. Women on oestrogens may have altered free serum cortisol kinetics and thus may be potentially overexposed to glucocorticoids.

Diagnostic performance of salivary cortisol and serum osteocalcin measurements in patients with overt and subclinical Cushing's syndrome

OBJECTIVE

The cut-off value for salivary cortisol measurement for the diagnosis of Cushing's syndrome (CS) may depend both on the severity of the disease and the composition of control group. Therefore, we examined the utility of midnight salivary cortisol measurements in patients who were evaluated for signs and symptoms of CS or because they had adrenal incidentalomas. Because serum osteocalcin (OC) is considered as a sensitive marker of hypercortisolism, we also investigated whether OC could have a role in the diagnosis of CS.

PATIENTS AND METHODS

Each of the 151 patients was included into one of the following groups: (A) overt CS (n=23), (B) subclinical CS (n=18), (C) inactive adrenal adenomas (n=40), (D) patients without HPA disturbances (n=70). Patients (C+D) were used as controls. Serum, salivary and urinary cortisol, and OC were measured by electrochemiluminescence immunoassay.

RESULTS

Group A had suppressed OC as compared to both group B and group (C+D). Serum and salivary cortisol concentrations showed strong negative correlations with OC in patients with overt CS. The areas under the curves of salivary and serum cortisol at 24:00 h (0.9790 and 0.9940, respectively) serum cortisol after low dose dexamethasone test (0.9930) and OC (0.9220) obtained from ROC analysis for the diagnosis of overt CS were not statistically different.

CONCLUSION

This study confirms the usefulness of midnight salivary cortisol measurements in the diagnosis of overt CS in the everyday endocrinological praxis. Our results suggest that OC may have a role in the diagnosis of overt CS.

Clinical Review#: The diagnosis and management of central hypoadrenalism

CONTEXT

Adrenal failure secondary to hypothalamo-pituitary disease is a common clinical problem which has serious repercussions. It is essential to perform validated diagnostic procedures and manage such patients with clear objectives and based on well-established replacement programs.

EVIDENCE ACQUISITION

PubMed was searched for all data reflecting pituitary hypoadrenalism dating back to 1960 in order to establish a published database.

EVIDENCE SYNTHESIS

The results from published studies were assessed in the light of the author's extensive personal experience dating back some 30 yr in clinical endocrinology, in an attempt to provide clear diagnostic and management advice.

CONCLUSIONS

While much of the physiology of the hypothalamo-pituitary-adrenal axis is well understood, its clinical assessment and diagnostic procedures to establish the need for replacement are still far from perfect, and to a certain extent clinical judgement is still vital. In terms of replacement therapies, these are still far from optimal in terms of quality of life and mortality, although they are increasingly being based on objective evidence rather than established practice. However, it is anticipated that newer replacement protocols will improve a situation that has previously changed little for many years.

Attentional and emotional mechanisms of pain processing and their related factors: a structural equations approach

BACKGROUND/OBJECTIVE

It is known that maladaptive attentional and emotional mechanisms of pain processing - as indicated by constructs such as pain hypervigilance, pain-related anxiety and pain catastrophizing - play an important role in the development and maintenance of chronic pain conditions. However, little is known to date about the potential risk factors for these forms of maladaptive processing. The aim of the present study was to shed more light on this issue. A very comprehensive set of predictor variables was examined in healthy pain-free subjects.

METHOD

Participants were 92 young and healthy subjects (mean [+/- SD] age 26.99+/-6.90 years; 47 men, 45 women). Maladaptive attentional and emotional mechanisms of pain processing were assessed by self-report measures of pain hypervigilance, pain-related anxiety and pain catastrophizing, as well as by a dot-probe task. The comprehensive set of predictor variables included measures of affective and bodily distress (depression, anxiety and somatization), experimental pain sensitivity, and cortisol reactivity. Directed relationships were estimated by using structural equation modelling.

RESULTS

Structural equation modelling revealed a significant path from affective and bodily distress to self-reported maladaptive attentional and emotional pain processing. In contrast, the paths from pain sensitivity and cortisol reactivity did not reach the level of significance.

CONCLUSION

These results support the position that anxiety and depression, as well as somatization, contribute to the aberrance of attentional and emotional mechanisms of pain processing. Surprisingly, the assumption of a close relationship between these maladaptive mechanisms of pain processing and pain sensitivity could not be confirmed.

Preclinical challenges in steroid analysis of human samples

Preclinical challenges in the analysis of steroid hormones are primarily determined by biological factors involved in the physiology and pathophysiology of hormone secretion. Major biologically influencing factors like age, sex, pubertal stage, pregnancy, phase of the menstruation, and diurnal rhythm have to be considered in the definition of reference ranges for steroids and their clinical interpretation. Hitherto, in clinical routine laboratories steroids were mainly determined by direct immunoassays applied on automated platforms, which are simple, rapid and cheap if a high number of samples are measured. However, technical factors like cross-reactivity of related steroid metabolites or limited analytical ranges have to be taken in account and may impair accuracy and precision of these direct methods. The actual development of mass spectrometry based analytical platforms for the determination of single steroid or steroid patterns seems to be an alternative analytical approach combining multi-parametric analysis, high sensitivity and specificity as well simple sample pre-treatment, robustness and low running costs for steroid analysis. This short review will give an overview about biological influencing factors and technical disturbing factors of routinely used immunoassay for the analysis of steroids. The application of LC-MS/MS as an alternative routine high-throughput platform for steroid analysis and its perspective role in the standardization and harmonisation of steroid measurements in clinical routine application will be discussed.

Is metabolic syndrome a mild form of Cushing's syndrome?

The Metabolic Syndrome is a diagnosis of increasing prevalence that is noted to share multiple clinical features with Cushing's syndrome. Several studies suggest abnormalities in the Hypothalamic-Pituitary-Adrenal axis to be associated with this disease and tissue-specific hypercortisolemia is being investigated as a possible contributing factor. More research is needed to explore the relation between cortisol and the metabolic syndrome which, if confirmed, will have major therapeutic and public health implications.

Clinical accuracy of midnight salivary cortisol measured by automated electrochemiluminescence immunoassay method in Cushing's syndrome

BACKGROUND

The diagnosis of Cushing's syndrome (CS) represents a challenge for endocrinologists. Several screening tests are used, but none of them seems to be the gold standard for the diagnosis. The aim of this study was to confirm the diagnostic value of salivary cortisol (SC) as a first-level screening test and to evaluate the clinical performance of a electrochemiluminescence immunoassay (ECLIA) method.

METHODS

In 33 patients with a strong clinical suspicion of CS, we evaluated urinary free cortisol, circadian rhythm plasma cortisol (PC) and morning PC after low-dose dexamethasone suppression test (LDDST). At the same sampling times, we evaluated SC analysed by the same automated method. Correlation studies were evaluated by Spearman index (significance P < 0.05).

RESULTS

On the basis of biochemical results CS was confirmed in 21/33. SC was significantly correlated to PC at 12:00 and 23:00. Thus, we chose 8.3 nmol/L as midnight SC cut-off value with 100% sensitivity and 97.4% specificity. The cut-off chosen after LDDST was 1.7 nmol/L (100% sensitivity and 72% specificity).

CONCLUSION

SC assay showed a good clinical accuracy and the ECLIA method can be used in clinical routine to obtain fast results easily.

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.

Evaluation of plasma, salivary, and urinary cortisol levels for diagnosis of Cushing's syndrome

As a screening test for Cushing's syndrome, the evaluation of late-night cortisol levels is indispensable. We evaluated the usefulness and accuracy of plasma, urinary, and salivary cortisol levels measured late at night for the diagnosis of Cushing's syndrome. High cortisol levels (> 5 microg/dL) during the night are indicative of Cushing's syndrome, although night plasma cortisol levels are not readily reproducible because of the stressful situation. There was no correlation between plasma and urinary cortisol levels late at night, and late-night urinary cortisol levels provided weak information for the diagnosis of Cushing's syndrome. By contrast, late-night plasma and salivary cortisol levels showed a positive correlation, and salivary cortisol sampling was found to be useful for the diagnosis of Cushing's syndrome, because more than 0.4 microg/dL of late-night salivary cortisol levels gave a sensitivity of 86% and a specificity of 100% in our hospital. This method is also useful for the diagnosis of early or mild stage Cushing's syndrome, so-called subclinical Cushing's syndrome. Inherent differences between assays make it difficult to define optimal diagnostic criteria. However, the relative levels of salivary cortisol ratio, which is presented as a relative level, compared with the mean levels of healthy subjects in each institute, is useful for the screening of Cushing's syndrome as the cut-off level of 1.5 shows both high sensitivity and specificity in subclinical and overt Cushing's syndrome. Late-night salivary cortisol measurement is therefore a primary method of choice in the screening of patients suspected of having Cushing's syndrome.