A comparison of the use of urinary cortisol to creatinine ratios and nocturnal salivary cortisol in the evaluation of cyclicity in patients with Cushing's syndrome

The Utility of Salivary Cortisone in the Overnight Dexamethasone Suppression Test in Adrenal Incidentalomas

CONTEXT

Guidelines recommend the assessment of cortisol secretion in patients with adrenal incidentalomas (AI) using the overnight dexamethasone suppression test (ONDST). This requires attendance at a health care facility and venepuncture. Alternatively, the ONDST can be done by measuring salivary cortisol and cortisone, which can be collected at home.

OBJECTIVE

We aimed to assess the utility of these measurements in patients with AI.

METHODS

A retrospective analysis of data from 173 patients with AI who underwent an ONDST and salivary cortisol/cortisone diurnal studies. Serum and salivary cortisol and salivary cortisone were collected at 09:00, late night, and at 09:00 the following morning after dexamethasone. Dexamethasone levels were measured in the postdexamethasone samples. Serum and salivary samples were analyzed with liquid chromatography-tandem mass spectrometry.

RESULTS

We identified a strong correlation between salivary cortisone and serum cortisol after 1 mg of dexamethasone (r = 0.95). Stepwise multivariate regression showed that postdexamethasone salivary cortisone, baseline serum cortisol, salivary cortisone suppression (predexamethasone/postdexamethasone ratio), and sex were the only significant or near-significant independent variables. Performance of predictive indices using these 4 parameters (sensitivity = 88.5%, specificity = 91.2%; kappa 0.80) and postdexamethasone salivary cortisone alone (sensitivity = 85.3%, specificity = 91.7%; kappa 0.77) were comparable when used to predict an ONDST serum cortisol of ≤50 nmol/L. No correlation was observed with any of the other measured parameters.

CONCLUSION

In AI patients, after dexamethasone, salivary cortisone correlates very strongly with serum cortisol in the ONDST and could therefore be used as an alternative sampling method which does not require venepuncture or attendance at hospital.

Diagnostic challenges in cyclic Cushing's syndrome: a systematic review

Cyclic Cushing's syndrome is a subentity of Cushing's syndrome in which phases of biochemical hypercortisolism (peaks) are followed by spontaneous periods of physiological or even hypocortisolaemic cortisol secretion (troughs). To identify common features of cyclic Cushing's syndrome, we systematically reviewed single case reports and case series in MEDLINE from database inception to Oct 10, 2022, and identified 707 articles, of which 149 articles were assessed for eligibility and 118 articles (covering 212 cases) were included in the analysis. Pituitary tumours accounted for 67% of cases of cyclic Cushing's syndrome (n=143), ectopic tumours for 17% (n=36), and adrenal tumours for 11% (n=23). Occult tumours accounted for 2% of cases (n=4), and 3% of cases were unclassified (n=6). We compared the clinical symptoms and comorbidities of patients with cyclic Cushing's syndrome with those of patients with non-cyclic Cushing's syndrome and observed no major difference. In adrenocorticotropic hormone (ACTH)-dependent cyclic Cushing's syndrome, bilateral inferior petrosal sinus sampling had a positive (ie, true pituitary) and negative (ie, true ectopic) predictive value of 100% when performed during periods of hypercortisolism, versus a positive predictive value of 73% and a negative predictive value of 86% when performed, irrespective of cortisolaemic status. Overall, 6% of patients (n=12) with cyclic Cushing's syndrome had unnecessary surgery due to misclassification. Remission rates were significantly lower and the time to remission significantly longer in patients with cyclic Cushing's syndrome compared with patients with non-cyclic Cushing's syndrome (p<0·001). Variations in biochemical test results due to unpredictable cycle duration and frequency might cause diagnostic challenges resulting in misdiagnoses and missed diagnoses.

Clinically relevant urine creatinine underestimation in the low concentration range on the Siemens Dimension Vista®

While considerable efforts have been accomplished to standardize the measurement of plasma creatinine (PCr), urine creatinine (UCr) has not been subject to the same scrutiny. UCr is importantly used when measuring biomarkers in spot urines, to assess urine output and variable dilution of urine samples. Here, we report underestimation of Jaffe UCr measurements on the Siemens Dimension Vista® analyzer, critically affecting samples with UCr ≤2 mmol/L. We demonstrate that this error is caused by automatic urine pre-dilution by the Vista's «urine mode», and that UCr measured in «plasma mode» without pre-dilution does not present this error. In the absence of a comprehensive solution proposed by Siemens, we propose simple formulae that can be easily implemented in a laboratory to correct these low UCr measurements. Importantly, the observed UCr underestimation can significantly influence reported results for biomarkers/UCr ratios measured in spot urine. Indeed, these results can be overestimated up to +84.4 % before correction using our formulae. This can sometimes lead to misclassification according to clinical thresholds, e.g. Kidney disease: improving global outcomes (KDIGO) guidelines for urine albumin/creatinine. This highlights the need for every clinical laboratory to assess the detection limits of their assays, including for lesser-discussed parameters such as UCr. Indeed, the error we reported here may affect other urine assays performing systematic urine pre-dilution and could have significant repercussions on the clinical management of patients.

Mechanism, diagnosis, and treatment of cyclic Cushing's syndrome: A review

Cushing's syndrome (CS) is caused by hypercortisolemia, leading to the occurrence of characteristic clinical symptoms. A small number of patients with CS have periodic and intermittent increases in cortisol levels, resulting in recurrent episodes of clinical symptoms. Such patients are known as having cyclic CS (CCS). The cortisol secretion cycle of patients with CCS is unpredictable, and laboratory tests often show negative results during the normal cortisol secretion period; therefore, the diagnosis and treatment of the disease are currently difficult. Although the pathogenesis of CCS remains uncertain, recent studies have suggested that it may be closely related to hypothalamic factors, feedback mechanisms, and tumor infarction. Our review summarizes the current state of research on the potential mechanisms, diagnosis, and treatment of CS and provides an outlook for future studies.

Consensus statement by the French Society of Endocrinology (SFE) and French Society of Pediatric Endocrinology & Diabetology (SFEDP) on diagnosis of Cushing's syndrome

Cushing's syndrome is defined by prolonged exposure to glucocorticoids, leading to excess morbidity and mortality. Diagnosis of this rare pathology is difficult due to the low specificity of the clinical signs, the variable severity of the clinical presentation, and the difficulties of interpretation associated with the diagnostic methods. The present consensus paper by 38 experts of the French Society of Endocrinology and the French Society of Pediatric Endocrinology and Diabetology aimed firstly to detail the circumstances suggesting diagnosis and the biologic diagnosis tools and their interpretation for positive diagnosis and for etiologic diagnosis according to ACTH-independent and -dependent mechanisms. Secondly, situations making diagnosis complex (pregnancy, intense hypercortisolism, fluctuating Cushing's syndrome, pediatric forms and genetically determined forms) were detailed. Lastly, methods of surveillance and diagnosis of recurrence were dealt with in the final section.

Cushing's syndrome: Overview of clinical presentation, diagnostic tools and complications

Cushing's syndrome (CS) is a severe condition that results from chronic exposure to elevated circulating cortisol levels; it is a rare but potentially life-threating condition, especially when not timely diagnosed and treated. Even though the diagnosis can be straightforward in florid cases due to their typical phenotype, milder forms can be missed. Despite the availability of different screening tests, the diagnosis remains challenging as none of the available tools proved to be fully accurate. Due to the ubiquitous effect of cortisol, it is easy understandable that its excess leads to a variety of systemic complications including hypertension, metabolic syndrome, bone damages and neurocognitive impairment. This article discusses clinical presentation of CS with an eye on the most frequent cortisol-related comorbidities and discuss the main pitfalls of first- and second-line tests in endogenous hypercortisolism diagnostic workup.

The diagnostic accuracy of increased late night salivary cortisol for Cushing's syndrome: a real-life prospective study

INTRODUCTION AND AIM

A prompt diagnosis of Cushing's Syndrome (CS) in high-risk populations is mandatory: 1-mg dexamethasone suppression test (1-mg DST), late night salivary cortisol (LNSC), and urinary-free cortisol (UFC) are recommended, despite thresholds calculated in retrospective studies. Our aim was to study the diagnostic accuracy of LNSC measured with chemiluminescence assay in a prospective study, confirming discrepancies with mass spectrometry (MS).

MATERIALS AND METHODS

We enrolled 117 controls and 164 suspected CS (CS = 47, non-CS = 117). In case of increased LNSC, high clinical suspicion of CS or adrenal incidentaloma, patients were hospitalized to exclude/confirm CS.

RESULTS

LNSC levels were higher in patients with suspected CS, CS, and non-CS than controls. Considering 16 nmol/L as threshold for CS, overall LNSC revealed SE 97% and SP 84% in the whole group of subjects considered, achieving positive/negative likelihood ratio of 5.56/0.045, respectively. 35 out of 81 subjects with increased LNSC were non-CS (15 diabetic and 20 obese): considering only those patients with increased likelihood to have a CS (the non-CS patients) SP decreased to 70%, and further reduced to 60% if we discharged subjects with adrenal incidentaloma. MS analyses reduced partially the number of false-positive LNSC.

CONCLUSIONS

LNSC measured in automated chemiluminescence is reliable in clinical practice: it present a high diagnostic accuracy to exclude hypercortisolism in patients with normal cortisol levels. MS could be used to reduce the number of false-positive results; nevertheless, some non-CS subjects with functional hypercortisolism could have a mild impairment of cortisol rhythm.

Characterization of cyclic Cushing's disease using late night salivary cortisol testing

OBJECTIVE

To characterize a cohort of patients with cyclic Cushing's disease (CD) in comparison with noncyclic CD using late night salivary cortisol (LNSC) and examine the diagnostic sensitivity of LNSC in comparison with that of 24-hour urine-free cortisol (UFC) in this population.

DESIGN

Retrospective study of patients with CD seen in our institution between 2008 and 2017.

PATIENTS

A total of 205 patients, including 17 (8%) with cyclic CD (based on a minimum of 3 peaks and 2 troughs in cortisol levels). In a secondary analysis, 38 patients (19%) with cyclic CD were identified (based on a criterion of at least 2 peaks and 1 trough).

MEASUREMENTS

Data on presentation, laboratory tests and outcomes were extracted. The diagnostic sensitivity of LNSC vs UFC in establishing cyclic CD was calculated. Kaplan-Meier analyses of recurrence after transsphenoidal pituitary surgery (TSS) were performed.

RESULTS

The interval between presentation and TSS was significantly longer in patients with cyclic CD (P < .0001) in comparison with those with noncyclic CD. The sensitivity of LNSC in establishing cyclic CD was 88% and was higher than that of UFC (12%, P = .007). There were no differences in remission and recurrence rates between patients with cyclic CD and those with noncyclic CD.

CONCLUSIONS

Patients with cyclic CD account only for a minority of those with CD, but may require a lengthier diagnostic evaluation. The use of LNSC on multiple occasions provides a more sensitive method of detecting cyclic CD than UFC. Outcomes of TSS in cyclic CD are comparable to those with noncyclic disease.

Variability of Late-Night Salivary Cortisol in Cushing Disease: A Prospective Study

BACKGROUND

The frequency of variable hormonogenesis in patients with Cushing disease (CD) but without cyclical symptoms is unclear.

AIM

To assess the frequency of variable hormonogenesis in patients presenting with CD.

METHODS

Over a 6-month period, patients with confirmed or suspected CD provided late-night salivary samples for up to 42 consecutive nights.

RESULTS

Of 19 patients confirmed to have CD, 16 provided at least 7 consecutive salivary samples, and 13 provided at least 21; these 16 patients are the subjects of this report. Twelve patients had at least three peak and two trough levels of late-night salivary cortisol (LNSC) but in only two patients were strict criteria for cyclical hormonogenesis fulfilled; variation was assessed as random in the others. Eight patients had de novo CD, and eight had recurrent/persistent disease. All patients with recurrent/persistent CD had two or more normal results, and in four of these patients, >50% of LNSC were normal. In six patients with de novo disease with at least one normal LNSC level, the maximum levels ranged from 1.55 to 15.5 times the upper limit of normal.

CONCLUSIONS

Extreme fluctuations of cortisol production, measured by sequential LNSC, are common in CD. In newly diagnosed disease, this may only occasionally impair diagnostic ability, whereas in most patients with recurrent/persistent disease after pituitary surgery, LNSC is frequently within the reference range, with potential to cause diagnostic problems.

Cushing's syndrome: a practical approach to diagnosis and differential diagnoses

Diagnosis of Cushing's syndrome (CS) and identification of the aetiology of hypercortisolism can be challenging. The Endocrine Society clinical practice guidelines recommends one of the four tests for initial screening of CS, namely, urinary-free cortisol, late night salivary cortisol, overnight dexamethasone suppression test or a longer low-dose dexamethasone suppression test, for 48 hours. Confirmation and localisation of CS requires additional biochemical and radiological tests. Radiological evaluation involves different imaging modalities including MRI with or without different radio-nuclear imaging techniques. Invasive testing such as bilateral inferior petrosal sinus sampling may be necessary in some patients for accurate localisation of the cause for hypercortisolism. This best practice review discusses a practical approach for the diagnostic evaluation of CS with a brief discussion on differential diagnoses, and cyclical CS, to enhance the skills of clinicians and laboratory personnel.

Recommendations of the Neuroendocrinology Department of the Brazilian Society of Endocrinology and Metabolism for the diagnosis of Cushing's disease in Brazil

Although it is a rare condition, the accurate diagnosis and treatment of Cushing's disease is important due to its higher morbidity and mortality compared to the general population, which is attributed to cardiovascular diseases, diabetes mellitus and infections. Screening for hypercortisolism is recommended for patients who present multiple and progressive clinical signs and symptoms, especially those who are considered to be more specific to Cushing's syndrome, abnormal findings relative to age (e.g., spinal osteoporosis and high blood pressure in young patients), weight gain associated with reduced growth rate in the pediatric population and for those with adrenal incidentalomas. Routine screening is not recommended for other groups of patients, such as those with obesity or diabetes mellitus. Magnetic resonance imaging (MRI) of the pituitary, the corticotropin-releasing hormone (CRH) test and the high-dose dexamethasone suppression test are the main tests for the differential diagnosis of ACTH-dependent Cushing's syndrome. Bilateral and simultaneous petrosal sinus sampling is the gold standard method and is performed when the triad of initial tests is inconclusive, doubtful or conflicting. The aim of this article is to provide information on the early detection and establishment of a proper diagnosis of Cushing's disease, recommending follow-up of these patients at experienced referral centers. Arch Endocrinol Metab. 2016;60(3):267-86.

Salivary markers of kidney function - Potentials and limitations

Saliva can be collected non-invasively, repeatedly and without trained personnel. It is a promising diagnostic body fluid with clinical use in endocrinology and dentistry. For decades, it is known that saliva contains also urea, creatinine and other markers of renal function. Clinical studies have shown that the salivary concentrations of these markers could be useful for the assessment of kidney function without the need of blood collection. This article summarizes the clinical and experimental data on the use of saliva as a diagnostic fluid in nephrology and points out the advantages, pitfalls, technical requirements and future perspective for the use of saliva as a novel potential diagnostic biofluid.

Cushing's syndrome

Chronic exposure to excess glucorticoids results in diverse manifestations of Cushing's syndrome, including debilitating morbidities and increased mortality. Genetic and molecular mechanisms responsible for excess cortisol secretion by primary adrenal lesions and adrenocorticotropic hormone (ACTH) secretion from corticotroph or ectopic tumours have been identified. New biochemical and imaging diagnostic approaches and progress in surgical and radiotherapy techniques have improved the management of patients. The therapeutic goal is to normalise tissue exposure to cortisol to reverse increased morbidity and mortality. Optimum treatment consisting of selective and complete resection of the causative tumour is necessay to allow eventual normalisation of the hypothalamic-pituitary-adrenal axis, maintenance of pituitary function, and avoidance of tumour recurrence. The development of new drugs offers clinicians several choices to treat patients with residual cortisol excess. However, for patients affected by this challenging syndrome, the long-term effects and comorbidities associated with hypercortisolism need ongoing care.

Paediatric cyclical Cushing's disease due to corticotroph cell hyperplasia

BACKGROUND

Cushing's disease is very rare in the paediatric population. Although uncommon, corticotroph hyperplasia causing Cushing's syndrome has been described in the adult population, but appears to be extremely rare in children. Likewise, cyclical cortisol hypersecretion, while accounting for 15 % of adult cases of Cushing's disease, has only rarely been described in the paediatric population. Here, we describe a very rare case of a 13-year old boy with cyclical cortisol hypersecretion secondary to corticotroph cell hyperplasia.

CASE PRESENTATION

The case is that of a 13-year old boy, presenting with a long history of symptoms and signs suggestive of hypercortisolism, who was found to have cyclical ACTH-dependent hypercortisolism following dynamic pituitary testing and serial late-night salivary cortisol measurements. The patient underwent endoscopic transsphenoidal resection of the pituitary. Early surgical remission was confirmed by undetectable post-operative morning plasma cortisol levels. Histology and immunocytochemistry of the resected pituitary tissue showed extensive corticotroph cell hyperplasia.

CONCLUSION

This report describes a rare case of cyclical Cushing's disease secondary to corticotroph hyperplasia in a paediatric patient. This highlights the challenging and varied nature of Cushing's disease and its diagnosis, and the need to keep a differential diagnosis in mind during the diagnostic process.

Cushing syndrome: update on testing

Endogenous hypercortisolism (Cushing syndrome) is one of the most enigmatic diseases in clinical medicine. The diagnosis and differential diagnosis of Cushing syndrome depend on proper laboratory evaluation. In this review, an update is provided on selected critical issues in the diagnosis and differential diagnosis of Cushing syndrome: the use of late-night salivary cortisol in initial diagnosis and for postoperative surveillance, and the use of prolactin measurement to improve the performance of inferior petrosal sinus sampling to distinguish Cushing disease from ectopic adrenocorticotropic hormone (ACTH) syndrome during differential diagnosis of ACTH-dependent Cushing syndrome.