Cushing's syndrome: a review of diagnostic tests

Bilateral inferior petrosal sinus sampling in the differential diagnosis of ACTH-dependent Cushing's syndrome: A reappraisal

Cushing's syndrome (CS) is a rare disorder, once exogenous causes have been excluded. However, when diagnosed, the majority of cases are adrenocorticotropic hormone (ACTH)-dependent, of which a substantial minority are due to a source outside of the pituitary, ectopic ACTH syndrome (EAS). Differentiating among pituitary-dependent CS, Cushing's disease (CD) and an ectopic source can be problematic. Because non-invasive tests in the evaluation of CS patients often lack adequate sensitivity and specificity, bilateral inferior petrosal sinus sampling (BIPSS), a minimally invasive procedure performed during the investigation of ACTH-dependent CS, can be extremely helpful. BIPSS is considered to be the gold standard for differentiating CD from the EAS. Furthermore, although such differentiation may indeed be challenging, BIPSS is itself a complex investigation, especially in recent times due to the widespread withdrawal of corticotrophin-releasing hormone and its replacement by desmopressin. We review current published data on this investigation and, in the light of this and our own experience, discuss its appropriate use in diagnostic algorithms.

The 1 mg overnight dexamethasone suppression test: a danger to the adrenal gland?

PURPOSE OF REVIEW

The 1 mg overnight dexamethasone suppression test (ONDST) with a cutoff cortisol value of 1.8 mcg/dl (50 nmol/l) is routinely used for the assessment of incidental, benign adrenal nodules. Patients with an abnormal test are diagnosed with mild autonomous cortisol secretion (MACS). This timely commentary reviews the origins of the ONDST, its relationship to the diagnoses of MACS, and whether this is clinically relevant for clinical care.

RECENT FINDINGS

Millions of incidental adrenal nodules are found on CT scans annually. Several papers in the last three years discuss and advocate for the diagnose of MACS via the ONDST.

SUMMARY

An ONDST cutoff of 1.8 mcg/dl (50 nmol/l) in patients with no clinical features of Cushing's syndrome will produce false positive results and a diagnosis of MACS that could result in unnecessary adrenalectomy.

Cushing syndrome due to ectopic ACTH secreting pheochromocytoma

In this case report, we present a case of a woman in her late 30s who presented with bilateral motor weakness, headache, hyperglycaemia and hypertension. Investigations revealed very high 24-hour urine cortisol of 90 524, ectopic adrenocorticotropic hormone secreting pheochromocytoma, normal metanephrine levels and empty sella, which has never been reported. CT chest and abdomen revealed enlarged left adrenal gland with large necrotic mass 4.7×4.0 cm most likely neoplastic lesion. The patient was cured after surgical removal of the left adrenal mass. Histological examination revealed 3.5×2.5×2 cm mass consistent with pheochromocytoma. After surgery and a short stay in the intensive care unit, the patient started improving and both antihypertensive treatment and insulin injections were withdrawn.

Diagnostic testing of autonomous cortisol secretion in adrenal incidentalomas

OBJECTIVE

Autonomous cortisol secretion (ACS) is a condition with ACTH-independent cortisol overproduction from adrenal incidentalomas (AI) or adrenal hyperplasia. The hypercortisolism is often mild, and most patients lack typical clinical features of overt Cushing's syndrome (CS). ACS is not well defined and diagnostic tests lack validation.

METHODS

Retrospective study of 165 patients with AI evaluated clinically and by assay of morning plasma ACTH, late-night saliva cortisol, serum DHEA sulphate (DHEAS), 24-h urine-free cortisol, and cortisol after dexamethasone suppression.

RESULTS

Patients with AI (n = 165) were diagnosed as non-functioning incidentalomas (NFI) (n = 82) or ACS (n = 83) according to current European guidelines. Late-night saliva cortisol discriminated poorly between NFI and ACS, showing a high rate of false-positive (23/63) and false-negative (38/69) results. The conventional low-dose dexamethasone suppression test (LDDST) did not improve the diagnostic specificity, compared with the 1 mg overnight DST. Receiver operating characteristic curve analysis of DHEAS in the two cohorts demonstrated an area under the curve of 0.76 (P < 0.01) with a sensitivity for ACS of 58% and a specificity of 80% using the recommended cutoff at 1.04 µmol/L (40 µg/dL).

CONCLUSION

We here demonstrate in a large retrospective cohort of incidentaloma patients, that neither DHEAS, late-night saliva cortisol nor 24-h urine free cortisol are useful to discriminate between non-functioning adrenal incidentalomas and ACS. The conventional LDDST do not add further information compared with the 1 mg overnight DST. Alternative biomarkers are needed to improve the diagnostic workup of ACS.

Neurobiological mechanisms underlying sex-related differences in stress-related disorders: Effects of neuroactive steroids on the hippocampus

Men and women differ in their vulnerability to a variety of stress-related illnesses, but the underlying neurobiological mechanisms are not well understood. This is likely due to a comparative dearth of neurobiological studies that assess male and female rodents at the same time, while human neuroimaging studies often don't model sex as a variable of interest. These sex differences are often attributed to the actions of sex hormones, i.e. estrogens, progestogens and androgens. In this review, we summarize the results on sex hormone actions in the hippocampus and seek to bridge the gap between animal models and findings in humans. However, while effects of sex hormones on the hippocampus are largely consistent in animals and humans, methodological differences challenge the comparability of animal and human studies on stress effects. We summarise our current understanding of the neurobiological mechanisms that underlie sex-related differences in behavior and discuss implications for stress-related illnesses.

Diagnostic accuracy of Bilateral Inferior Petrosal Sinus Sampling: The Experience of a Tertiary Centre

Purpose To assess the accuracy of bilateral inferior petrosal sinus sampling both in the differential diagnosis of adrenocorticotrophic hormone dependent Cushing’s syndrome and predicting the localization on the pituitary.

Methods The authors evaluated all patients that undergone bilateral inferior petrosal sinus sampling in a tertiary centre, between January 1995 and March 2018. The probable diagnosis of Cushing’s disease was made when the basal central/peripheral gradient was>2 and/or>3 after stimulation with corticotrophin releasing hormone. The localization was suggested when the inter-sinus gradient was>1.4. The results obtained were compared with the post operatory results: compatible histology and positive immunohistochemistry to adrenocorticotrophic hormone and/or the presence of criteria of cure. Sensitivity, specificity and predictive positive value were calculated.

Results A total of 49 patients were evaluated (75.5% female; mean age 45.4±16.3 years old). Bilateral inferior petrosal sinus sampling was compatible with Cushing’s disease in 27 out of 28 confirmed cases in histology or by criteria of cure, and was compatible with ectopic secretion in the 2 cases confirmed as ectopic secretion of adrenocorticotrophic hormone (sensitivity 96.4%; specificity 100%). The lateralization calculated was concordant with the results after surgery in 17 out of 27 patients with Cushing’s disease – predictive positive value of 63%. Magnetic resonance had a higher predictive value to lateralization – 70.0%.

Conclusions Bilateral inferior petrosal sinus sampling is a safe and reliable procedure to diagnose Cushing’s disease, with great sensitivity and specificity. Nevertheless, the capacity of this procedure to lateralize the lesion inside the pituitary is limited.

Two types of ectopic Cushing syndrome or a continuum? Review

BACKGROUND

Two types of ectopic Cushing syndrome (ECS) are described: ECS associated with aggressive neoplasms, and ECS with indolent and occult tumors, however, there is a lack of studies that thoroughly review their characteristics.

METHODS

A systematic review was carried out on PUBMED of all the papers about the ECS, in order to better define the types of this subcategory of Cushing's syndrome, highlighting the differential aspects between these subgroups.

RESULTS

It was found that in 50% of cases the prototypic "aggressive" ECS is caused by small cell lung carcinomas (SCLC). In these cases, the clinical presentation may be atypical, predominating the signs and symptoms derived from the protein catabolism. Cortisol and ACTH levels are extremely high, the clinical presentation is abrupt (< 3-6 months) and the tumor is usually advanced, being impossible a curative treatment. On the other hand, "indolent" ECS is mainly represented by carcinoid tumors (CT). In these cases the clinical presentation overlaps enormously with that of Cushing's disease (CD). Cortisol and ACTH levels are slightly elevated, the clinical presentation is progressive (> 6 months) and the prognosis is usually good, and a curative treatment is possible in about 75% of the cases.

CONCLUSION

Although there is no absolute differentiation between the two extremes of ECS, a classification could be established in two groups, guided by its clinical and biochemical characteristics, and mainly by the type and stage of the ACTH-secreting tumor. However, a small percentage of tumors do not fit in this simple grouping, and may present both phenotypes or an intermediate one.

The Ectopic Adrenocorticotropic Hormone Syndrome: Rarely Easy, Always Challenging

Despite modern imaging techniques, differentiating ectopic adrenocorticotropic hormone (ACTH) syndrome from pituitary-dependent Cushing's syndrome, Cushing's disease, is especially difficult when well-differentiated carcinoids are the source of ACTH secretion, particularly pulmonary carcinoid tumors. ACTH-secreting pulmonary carcinoids, like the corticotroph adenomas causing Cushing's disease, are often small and difficult to detect, and patients present with a gradual onset of the classical signs and symptoms of Cushing's syndrome, indistinguishable from the presentation of Cushing's disease. Hence, the differential diagnosis relies on a combination of clinical assessment, dynamic biochemical tests, inferior petrosal sinus sampling, and multimodal imaging, each with its own caveats and pitfalls.

Metabolomic Biomarkers in Urine of Cushing's Syndrome Patients

Cushing’s syndrome (CS) is a disease which results from excessive levels of cortisol in the human body. The disorder is associated with various signs and symptoms which are also common for the general population not suffering from compound hypersecretion. Thus, more sensitive and selective methods are required for the diagnosis of CS. This follow-up study was conducted to determine which steroid metabolites could serve as potential indicators of CS and possible subclinical hypercortisolism in patients diagnosed with so called non-functioning adrenal incidentalomas (AIs). Urine samples from negative controls (n = 37), patients with CS characterized by hypercortisolism and excluding iatrogenic CS (n = 16), and patients with non-functioning AIs with possible subclinical Cushing’s syndrome (n = 25) were analyzed using gas chromatography-mass spectrometry (GC/MS) and gas chromatograph equipped with flame ionization detector (GC/FID). Statistical and multivariate methods were applied to investigate the profile differences between examined individuals. The analyses revealed hormonal differences between patients with CS and the rest of examined individuals. The concentrations of selected metabolites of cortisol, androgens, and pregnenetriol were elevated whereas the levels of tetrahydrocortisone were decreased for CS when opposed to the rest of the study population. Moreover, after analysis of potential confounding factors, it was also possible to distinguish six steroid hormones which discriminated CS patients from other study subjects. The obtained discriminant functions enabled classification of CS patients and AI group characterized by mild hypersecretion of cortisol metabolites. It can be concluded that steroid hormones selected by applying urinary profiling may serve the role of potential biomarkers of CS and can aid in its early diagnosis.

Incidence of Cushing's syndrome in patients with significant hypercortisoluria

OBJECTIVE

To investigate the incidence of Cushing's syndrome (CS) in patients with significant hypercortisoluria and the performance of urinary free cortisol (UFC) screening.

DESIGN

Retrospective file review.

METHODS

The computerized database of a publicly funded health maintenance organization (HMO) in Israel was searched for all patients who underwent 24-h UFC testing in 2005-2014 with a result of more than twice the upper limit of normal (ULN). The patients' medical files were reviewed for a subsequent diagnosis of CS by an expert endocrinologist. Findings were evaluated for patterns in CS diagnosis and UFC testing over time.

RESULTS

Of 41 183 individuals tested, 510 (1.2%) had UFC >2× ULN (214 >3× ULN). Eighty-five (16.7%) individuals were diagnosed with CS (63 female and mean age 47.2 ± 15.1 years), mainly Cushing's disease (55.3%) or adrenal Cushing's syndrome (37.6%). The number of UFC tests increased steadily, from 1804 in 2005 to 6464 in 2014; yet, the resultant detection rate of CS remained generally stable. The calculated incidence of CS in the general HMO-insured population based only on the patients identified in the present cohort was 4.5 new cases/million/year (median 4.9/million/year, range 1.7-5.9/million/year), which was also relatively stable. The most common reason for referral for UFC screening was obesity. Of the 148 patients before bariatric surgery with UFC >2× ULN, 2 were diagnosed with CS.

CONCLUSIONS

The incidence of CS is higher than previously suggested. The consistently increasing number of UFC tests being performed has not been accompanied by a similar increase in CS detection rate. The expected yield of routine UFC testing before bariatric surgery is low.

Bilateral inferior petrosal sinus sampling

Simultaneous bilateral inferior petrosal sinus sampling (BIPSS) plays a crucial role in the diagnostic work-up of Cushing's syndrome. It is the most accurate procedure in the differential diagnosis of hypercortisolism of pituitary or ectopic origin, as compared with clinical, biochemical and imaging analyses, with a sensitivity and specificity of 88-100% and 67-100%, respectively. In the setting of hypercortisolemia, ACTH levels obtained from venous drainage of the pituitary are expected to be higher than the levels of peripheral blood, thus suggesting pituitary ACTH excess as the cause of hypercortisolism. Direct stimulation of the pituitary corticotroph with corticotrophin-releasing hormone enhances the sensitivity of the procedure. The procedure must be undertaken in the presence of hypercortisolemia, which suppresses both the basal and stimulated secretory activity of normal corticotrophic cells: ACTH measured in the sinus is, therefore, the result of the secretory activity of the tumor tissue. The poor accuracy in lateralization of BIPSS (positive predictive value of 50-70%) makes interpetrosal ACTH gradient alone not sufficient for the localization of the tumor. An accurate exploration of the gland is recommended if a tumor is not found in the predicted area. Despite the fact that BIPSS is an invasive procedure, the occurrence of adverse events is extremely rare, particularly if it is performed by experienced operators in referral centres.

Hypothalamic-Pituitary--Adrenal Axis-Feedback Control

The hypothalamo-pituitary-adrenal axis (HPA) is responsible for stimulation of adrenal corticosteroids in response to stress. Negative feedback control by corticosteroids limits pituitary secretion of corticotropin, ACTH, and hypothalamic secretion of corticotropin-releasing hormone, CRH, and vasopressin, AVP, resulting in regulation of both basal and stress-induced ACTH secretion. The negative feedback effect of corticosteroids occurs by action of corticosteroids at mineralocorticoid receptors (MR) and/or glucocorticoid receptors (GRs) located in multiple sites in the brain and in the pituitary. The mechanisms of negative feedback vary according to the receptor type and location within the brain-hypothalmo-pituitary axis. A very rapid nongenomic action has been demonstrated for GR action on CRH neurons in the hypothalamus, and somewhat slower nongenomic effects are observed in the pituitary or other brain sites mediated by GR and/or MR. Corticosteroids also have genomic actions, including repression of the pro-opiomelanocortin (POMC) gene in the pituitary and CRH and AVP genes in the hypothalamus. The rapid effect inhibits stimulated secretion, but requires a rapidly rising corticosteroid concentration. The more delayed inhibitory effect on stimulated secretion is dependent on the intensity of the stimulus and the magnitude of the corticosteroid feedback signal, but also the neuroanatomical pathways responsible for activating the HPA. The pathways for activation of some stressors may partially bypass hypothalamic feedback sites at the CRH neuron, whereas others may not involve forebrain sites; therefore, some physiological stressors may override or bypass negative feedback, and other psychological stressors may facilitate responses to subsequent stress.

Late-night salivary cortisol has a better performance than urinary free cortisol in the diagnosis of Cushing's syndrome

CONTEXT

The comparison of variability, reproducibility, and diagnostic performance of late-night salivary cortisol (LNSF) and urinary free cortisol (UFC) using concurrent and consecutive samples in Cushing's syndrome (CS) is lacking. Objectives, Patients, and Methods: In a prospective study, we evaluated 3 simultaneous and consecutive samples of LNSF by RIA and UFC by liquid chromatography associated with tandem mass spectrometry in Cushing's disease (CD) patients (n = 43), adrenal CS patients (n = 9), and obese subjects (n = 18) to compare their diagnostic performances. In CS patients, we also performed a modified CS severity index.

RESULTS

There was no difference in the coefficient of variation (percentage) between LNSF and UFC among the 3 samples obtained for each patient with Cushing's disease (35 ± 26 vs 31 ± 24), adrenal CS (28 ± 14 vs 22 ± 14), and obesity (39 ± 37 vs 48 ± 20). LNSF confirmed the diagnosis of hypercortisolism even in the presence of normal UFC in 17.3% of CS, whereas the inverse situation was not observed for UFC. The area under the receiver-operating characteristic curves for LNSF was 0.999 (95% credible interval [CI] 0.990-1.00) and for UFC was 0.928 (95% CI 0.809-0.987). The ratio between areas under the curve was 0.928 (95% CI 0.810-0.988), indicating better performance of LNSF than UFC in diagnosing CS. There was no association between the CS severity index and the degree of biochemical hypercortisolism.

CONCLUSION

Our data show that despite similar variability between both methods, LNSF has a superior diagnostic performance than UFC and should be used as the primary biochemical diagnostic test for CS diagnosis.

Differentiating between Cushing's disease and pseudo-Cushing's syndrome: comparison of four tests

OBJECTIVE

To evaluate the diagnostic performance of four different tests in order to differentiate between Cushing's disease (CD) and pseudo-Cushing's syndrome (PCS).

METHODS

In this prospective study, a total of 73 patients with clinical features of hypercortisolism and insufficient suppression of serum cortisol after 1 mg overnight dexamethasone and/or an elevated excretion of cortisol in 24-h urine samples were included. The circadian rhythm of serum cortisol levels as well as midnight serum cortisol (MserC) levels were assessed in all 73 patients. Late-night salivary cortisol (LNSC) concentrations were obtained in 44 patients. The dexamethasone-CRH (Dex-CRH) test was performed in 54 patients.

RESULTS

FIFTY-THREE PATIENTS WERE DIAGNOSED WITH CD AND SUBSEQUENTLY TREATED. TWENTY PATIENTS WERE CLASSIFIED AS HAVING PSC. SERUM CORTISOL CIRCADIAN RHYTHM: the diurnal rhythmicity of cortisol secretion was retained in PCS. A cortisol midnight:morning ratio of >0.67 is highly suggestive of CD (positive predictive value (PPV) 100% and negative predictive value (NPV) 73%). MserC concentration >243 nmol/l has a PPV of 98% in predicting true CD (NPV 95%). LNSC level >9.3 nmol/l predicted CD in 94% of patients (NPV 100%). Dex-CRH test: after 2 days of dexamethasone suppression, a CRH-stimulated cortisol level >87 nmol/l (T=15 min) resulted in a PPV of 100% and an NPV of 90%.

CONCLUSION

The Dex-CRH test as well as a single measurement of cortisol in serum or saliva at late (mid-) night demonstrated high diagnostic accuracy in differentiating PCS from true CD.

Laparoscopic adrenalectomy for co-secreting aldosterone and cortisol adenomas

There are few published data on aldosterone and cortisol co-secreting adrenal tumours. Failure to perform comprehensive preoperative endocrine investigations in patients with adrenal "incidentalomas" or in those thought to be secreting only one hormone may account for this. Clinically patients with such lesions may have evidence of hypertension and hypokalaemia with no features of cortisol excess. Preoperative diagnosis of such lesions with accurate endocrinological work up is essential to prevent adrenal insufficiency and haemodynamic crises following removal of such glands. We present a series of 4 patients with co-secreting tumours treated by laparoscopic adrenalectomy between September 2010 and March 2011. Our experience suggests that dual secretors are more common than originally thought. A high index of suspicion and adequate endocrine work up is paramount in diagnosing such tumours and in experienced hands, laparoscopic adrenalectomy with appropriate substitutive steroid cover is safe, feasible and curative for these functioning adrenal tumours.

Mini-review: pheochromocytomas causing the ectopic ACTH syndrome

Cushing's syndrome (CS) is a condition associated with high cortisol levels and affects around 0.7-2.4 cases per million population per year [1-3]. Approximately 80 % of cases of CS are secondary to excess adrenocorticotrophin (ACTH) secretion, while in around 20 % the primary abnormality lies in the adrenal, most often an adrenal adenoma or carcinoma. Of the ACTH-dependent causes, some 80-90 % are due to a pituitary adenoma-Cushing's disease-but in a significant proportion the cause is ectopic secretion from a non-pituitary source, the ectopic ACTH syndrome (EAS) [4]. The commonest source of ACTH secretion in these patients is a bronchial carcinoid. However, many other tumors are capable of secreting ACTH, and in most series a small but significant number are secondary to an ACTH-secreting pheochromocytoma. Amalgamating the data from 6 large series of patients with ectopic ACTH, pheochromocytoma was the source of ACTH secretion in 19 out of 363 patients (5.2 %) [5-11]. In this mini-review, we present a patient presenting to our department with a pheochromocytoma as well as Cushing's syndrome due to ectopic ACTH secretion by the pheochromocytoma, and we discuss published cases in the world literature to assess its significance. We emphasize the problems in the simultaneous management of these two serious endocrine conditions.

Standardized LC-MS/MS based steroid hormone profile-analysis

In order to overcome many limitations of immunoassays, high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) has the potential to find its place in the clinical laboratory medicine for quantification of steroid hormones. A prerequisite for the application of a new analytical procedure in clinical diagnostics is standardization to minimize analytical intra- and interlaboratory variability and inaccuracy. We evaluate a newly standardized HPLC-MS/MS assay in kit-format, developed for routine determination of 16 steroid hormones in human serum samples. Fifteen metabolites can be measured quantitatively, which include aldosterone, androstenedione, androsterone, corticosterone, cortisol, cortisone, 11-deoxycortisol, dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEAS), 17β-estradiol (E2), estrone (E1), etiocholanolone, 17α-hydroxyprogesterone (17OHP), progesterone, and testosterone. 11-Deoxycorticosterone is the only compound rated as semi-quantitative in this kit. The sample preparation is performed by solid phase extraction (SPE) on a 96-well plate. The standardized assay has been validated for human serum in terms of lower and upper limit of quantification (LLOQ 0.01-32 ng/mL, ULOQ 5-8000 ng/mL), linear correlation coefficient of calibration (R(2)>0.9966), intra- and inter-day precision (intra-day 1.1-8.8%, inter-day 5.2-14.8% and 8.2-18.6% for 11-deoxycorticosterone), accuracy (intra-day 88.3-115.5% and 109.3-128.2% for 11-deoxycorticosterone, inter-day 91.4-117.2% and 102.3-137.1% for 11-deoxycorticosterone), analytical total error (3.6-17.8%), proficiency test accuracy (85.4-113.4%), recovery (68-99%), and metabolite stability (freeze/thaw stability 95.5-108.1%, short term stability 86.9-107.2%). Inter-assay comparison with a routine reference HPLC-MS/MS assay and seven immunoassays demonstrates the outstanding high performance of this HPLC-MS/MS based kit by improvements in accuracy for progesterone, androstenedione, and 17OHP. Finally, results of two metyrapone tests demonstrate the potential of the standardized HPLC-MS/MS assay for the analysis of a comprehensive steroid hormone profile in clinical diagnostics.

Biomedical evaluation of cortisol, cortisone, and corticosterone along with testosterone and epitestosterone applying micellar electrokinetic chromatography

The validated micellar electrokinetic chromatography (MEKC) was proposed for the determination of five steroid hormones in human urine samples. That technique allowed for the separation and quantification of cortisol, cortisone, corticosterone, testosterone, and epitestosterone and was sensitive enough to detect low concentrations of these searched steroids in urine samples at the range of 2–300 ng/mL. The proposed MEKC technique with solid-phase extraction (SPE) procedure was simple, rapid, and has been successfully applied as a routine procedure to analyze steroids in human urine samples. The MEKC method offered a potential in clinical routine practice because of the short analysis time (8 min), low costs, and simultaneous analysis of five endogenous hormones. Due to its simplicity, speed, accuracy, and high recovery, the proposed method could offer a tool to determine steroid hormones as potential biomarkers in biomedical investigations, what was additionally revealed with healthy volunteers.

High prevalence of normal tests assessing hypercortisolism in subjects with mild and episodic Cushing's syndrome suggests that the paradigm for diagnosis and exclusion of Cushing's syndrome requires multiple testing

Many Endocrinologists believe that a single determination of eucortisolism or a single demonstration of appropriate suppression to dexamethasone excluded Cushing's syndrome, except in what was previously thought to be the rare patient with episodic or periodic Cushing's syndrome. We hypothesize that episodic Cushing's syndrome is relatively common and a single test assessing hypercortisolism may not be sufficient to accurately rule out or diagnose Cushing's syndrome and retrospectively examined the number of normal and abnormal tests assessing hypercortisolism performed on multiple occasions in 66 patients found to have mild and/or episodic Cushing's syndrome compared to a similar group of 54 patients evaluated for, but determined not to have Cushing's syndrome. We found that 65 of the 66 patients with Cushing's syndrome had at least one normal test of cortisol status and most patients had several normal tests. The probability of having Cushing's syndrome when one test was negative was 92% for 23:00 h salivary cortisol, 88% for 24-h UFC, 86% for 24-h 17OHS, and 54% for nighttime plasma cortisol. These results demonstrated that episodic hypercortisolism is highly prevalent in subjects with mild Cushing's syndrome and no single test was effective in conclusively diagnosing or excluding the condition. Rather, the paradigm for the diagnosis should be a careful history and physical examination and in those patients in whom mild Cushing's syndrome/disease is strongly suspected, multiple tests assessing hypercortisolism should be performed on subsequent occasions, especially when the patient is experiencing signs and symptoms of short-term hypercortisolism.

Cushing's syndrome: why is diagnosis so difficult?

Practicing and perfecting the art of medicine demands recognition that uncertainty permeates all clinical decisions. When delivering clinical care, clinicians face a multiplicity of potential diagnoses, limitations in diagnostic capacity, and "sub-clinical" disease identified by tests rather than by clinical manifestations. In addition, clinicians must recognize the rapid changes in scientific knowledge needed to guide decisions. Cushing's syndrome is one of several disorders in which there may be considerable difficulty and delay in diagnosis. This article describes a current model of clinical reasoning, some of its challenges, and the application of the principles of clinical epidemiology to meet some of those challenges.

Diagnostic efficacy of midnight cortisol and midnight ACTH in the diagnosis and localisation of Cushing's syndrome

Classical tests for diagnosis of Cushing's syndrome (CS) like urine free cortisol and dexamethasone suppression tests have limitations in various clinical settings. This study evaluated the usefulness of sleeping midnight serum cortisol (SMNC) as a diagnostic test for hypercortisolemia. A simultaneously done midnight plasma ACTH level was used to classify the disease as ACTH dependent or independent. Standard biochemical tests, SMNC, midnight plasma ACTH and appropriate imaging evaluated patients with a clinical suspicion of Cushing's syndrome. We evaluated 43 patients with CS comprising of 34 patients with Cushing's disease (CD), 2 patients with thymic carcinoid producing ectopic CS, 5 patients with adrenal carcinoma and 2 with adrenal adenoma. Thirteen patients with clinical suspicion were also evaluated with the above tests and CS was ruled out. SMNC, midnight plasma ACTH and dexamethasone suppressed cortisol was collected from patients with a suspicion of CS. SMNC was evaluated against histopathology as the gold standard. SMNC achieved 100% sensitivity in the diagnosis of endogenous CS at cut offs of 138 nmol/l and below. Raising the cut off to 207 nmol/l resulted in a test sensitivity of 90.5%. At a cut off of 1.65 pmol/l, midnight plasma ACTH could distinguish ACTH independent causes of CS with 100% sensitivity. We concluded that a single midnight collection could identify all patients with CS and classify the ACTH status at the proposed cut offs.

Stress, immunity and skin collagen integrity: evidence from animal models and clinical conditions

The skin is the largest organ of the human body and plays a major role in maintaining homeostasis and protection. As the main component of skin, collagen has a key role in providing integrity and elasticity to this organ. Several factors, including autoimmune disease, aging, and stress, can change the quantity and integrity of skin collagen. These factors impair collagen quality and consequently affect skin function. Stress seems to affect the integrity of skin collagen through glucocorticoid-mediated processes that alter its synthesis and degradation. Glucocorticoids also affect skin quality through modulation of the immune system. This review will briefly present comprehensive data from both animal and human studies delineating processes that modulate alterations in collagen in general, and will treat in more detail the consequences of stress on skin collagen.

Specificity of screening tests for Cushing's syndrome in an overweight and obese population

CONTEXT

Recent reports suggest a higher prevalence (1-5%) of Cushing's syndrome in certain patient populations with features of the disorder (e.g., diabetes), but the prevalence in the overweight and obese population is not known.

OBJECTIVE

The aim of the study was to evaluate the diagnostic performance of screening tests for Cushing's syndrome in overweight and obese subjects with at least two other features of the disorder.

DESIGN AND SETTING

We conducted a cross-sectional prospective study.

SUBJECTS AND METHODS

A total of 369 subjects (73% female) completed two or three tests: a 24-h urine cortisol, and/or late-night salivary cortisol, and/or 1 mg dexamethasone suppression test (DST). If any result was abnormal [based on laboratory reference range or cortisol after DST > or = 1.8 microg/dl (50 nmol/liter)], tests were repeated and/or a dexamethasone-CRH test was performed. Subjects with abnormal DST results and a low dexamethasone level were asked to repeat the test with 2 mg of dexamethasone.

RESULTS

In addition to obesity, subjects had a mean of five to six features of Cushing's syndrome. None was found to have Cushing's syndrome. Test specificities to exclude Cushing's syndrome for subjects who completed three tests were: urine cortisol, 96% [95% confidence interval (CI), 93-98%]; DST, 90% (95% CI, 87-93%); salivary cortisol, 84% by RIA (95% CI, 79-89%) and 92% by liquid chromatography-tandem mass spectrometry (95% CI, 88-95%). The combined specificity (both tests normal) for all combinations of two tests was 84 to 90%, with overlapping CIs.

CONCLUSION

These data do not support widespread screening of overweight and obese subjects for Cushing's syndrome; test results for such patients may be falsely abnormal.

[Diagnosis and differential diagnosis of Cushing's syndrome]

Because of the variability in the clinical expression of Cushing's syndrome, different biochemical tests and imaging techniques must be used for effective diagnosis and treatment. The clinical history is important to assess the general impact of hypercortisolism on organs and systems, as well as to guide suspicion toward more aggressive entities such as overt ectopic ACTH syndrome or to detect an iatrogenic etiology of Cushing's syndrome. The screening phase relies on tests that are sensitive but not specific, such as urinary free cortisol, nocturnal salivary cortisol and 1 mg dexamethasone suppression, which still require established assessment criteria. Confirmation can be obtained by repeating urinary cortisol, 2 mg/day dexamethasone suppression, both alone and combined with corticotropin releasing hormone (CRH), to exclude pseudoCushing states. ACTH dependency can be easily explored by ACTH measurements, but the differential diagnosis between pituitary and ectopic Cushing's disease is difficult and may require invasive procedures such as inferior petrosal sinus sampling. Sophisticated imaging and isotopic techniques play a significant role in locating the source of ACTH in ectopic syndromes but are not always effective. In general, biochemical and imaging tests should be combined in order to assess different mechanisms and perspectives of the syndrome. Rigorous methodology is essential to obtain accurate results, allowing a correct diagnosis and improving therapeutic performance in this devastating disease.

Comparison of 1 mg and 2 mg overnight dexamethasone suppression tests for the screening of Cushing's syndrome in obese patients

OBJECTIVE

Obesity is currently a major public health problem and one of the potential underlying causes of obesity in a minority of patients is Cushing's syndrome (CS). Traditionally, the gold standard screening test for CS is 1 mg dexamethasone overnight suppression test. However, it is known that obese subjects have high false positive results with this test.

DESIGN

We have therefore compared the 1 mg and 2 mg overnight dexamethasone suppression tests in obese subjects. Patients whose serum cortisol after ODST was >50 nM underwent and a low-dose dexamethasone suppression test (LDDST); 24-hour urine cortisol was collected for basal urinary free cortisol (UFC). For positive results after overnight 1-mg dexamethasone suppression test we also performed the overnight 2-mg dexamethasone suppression test.

PATIENTS

We prospectively evaluated 100 patients (22 men and 78 women, ranging in age from 17 to 73 years with a body mass index (BMI) >30 kg/m2 who had been referred to our hospital-affiliated endocrine clinic because of simple obesity. Suppression of serum cortisol to <50 nM (1.8 microg/dL) after dexamethasone administration was chosen as the cut-off point for normal suppression.

MEASUREMENTS

Thyroid function tests, lipid profiles, homocysteine, antithyroglobulin, anti-thyroid peroxidase antibody levels, vitamin B12, folate levels, insulin resistance [by homeostasis model assessment (HOMA)] and 1.0 mg postdexamethasone (postdex) suppression cortisol levels were measured.

RESULTS

We found an 8% false-positive rate in 1 mg overnight test and 2% in 2 mg overnight test (p=0.001). There was no correlation between the cortisol levels after ODST and other parameters.

CONCLUSIONS

Our results indicate that the 2 mg overnight dexamethasone suppression test (ODST) is more convenient and accurate than 1-mg ODST as a screening test for excluding CS in subjects with simple obesity.

[Pseudo-Cushing states]

Pseudo-Cushing syndromes are a heterogeneous group of disorders, including alcoholism, anorexia nervosa, visceral obesity, and depression, which share many of the clinical and biochemical features of Cushing's syndrome. The mechanisms responsible for the genesis of pseudo-Cushing's syndrome are poorly understood. It has been suggested that hypercortisolism of pseudo-Cushing syndrome may be the result of increased hypothalamic corticotrophin-releasing hormone (CRH) secretion in the context of a hypothalamic-pituitary-adrenal axis that is otherwise normally constituted. The substantial overlap in clinical and biochemical features among several patients with Cushing syndrome and those with pseudo-Cushing syndromes can make the differential diagnosis difficult. Distinguishing between pseudo-Cushing's syndrome and true Cushing's syndrome is critical for preventing the unnecessary and potentially harmful treatment of such patients. This brief review summarizes the main pathophysiological events of pseudo-Cushing syndromes and provides a useful strategy for differential diagnosis.

Clinical Use of Laboratory Tests for the Identification of Secondary Forms of Arterial Hypertension

The prevalence of secondary hypertension can be underestimated if appropriate tests are not performed. The importance of selecting patients with a high pre-test probability of secondary forms of hypertension is first discussed. The laboratory tests currently used for seeking a cause of hypertension are critically reviewed, with emphasis on their operative features and limitations. Strategies to identify primary aldosteronism, the most frequent form of secondary hypertension, and to determine its unilateral or bilateral causes are described. Treatment entails adrenalectomy in unilateral forms, and mineralocorticoid receptor blockade in bilateral forms. Renovascular hypertension is also a common, curable form of hypertension, that should be identified as early as possible to avoid the onset of cardiovascular target organ damage. The tests for its confirmation or exclusion are discussed. The various tests available for the diagnosis of pheochromocytoma, which is much rarer than the above but extremely important to identify, are also described, with emphasis on recent developments in genetic testing. Finally, the tests for diagnosing some rarer monogenic forms and other renal and endocrine causes of arterial hypertension are explored.

Basic infertility including polycystic ovary syndrome

Infertility in women has many possible causes and must be approached systematically. The most common cause of medically treatable infertility is the polycystic ovary syndrome (PCOS). This syndrome is common in young women and is the cause of anovulatory infertility in 70% of cases. It is therefore an important condition to screen and manage in primary care medical settings. In the past 10 years, insulin sensitization with weight loss or metformin has been shown to be a safe and effective treatment for PCOS infertility that eliminates the risk of multiple pregnancy and may reduce the risk of early pregnancy loss as compared with ovulation-inductor drugs. The authors believe metformin should be considered as first-line therapy because it has the advantage to allow for normal single ovulation, for reduced early pregnancy loss, and, most importantly, lifestyle modifications and weight loss before pregnancy. Losing weight not only improves fertility but also reduces adverse pregnancy outcomes associated with obesity.

[Endogenous Cushing's syndrome: clinical and laboratorial features in 73 cases]

We studied clinical and laboratorial features of 73 patients with endogenous Cushing's syndrome, subdivided as follows: 46 (63%) with Cushing's disease (CD), 21 (28.7%) with an adrenal tumor and 6 (8.2%) with ectopic ACTH secretion (EAS). The rate of typical manifestations of hypercortisolism was similar regardless its etiology. In 100% of cases of Cushing's syndrome we observed serum cortisol levels greater than 1.8 microg/dL in low-dose dexamethasone (DMS) suppression tests, as well as elevation of serum or salivary midnight cortisol. However, urinary free cortisol was normal in 11.5% of patients. ACTH levels were suppressed in patients with adrenal tumors, normal or high in CD and always high in EAS. In the 8-mg overnight DMS suppression test, serum cortisol suppression > 50% was observed in 78.2% of cases of CD and in 33.3% of subjects with EAS, while an 80% suppression was only seen in CD. After stimulation with CRH or DDAVP an ACTH increase > 35% occurred in 81% of individuals with CD and 16.6% of those with EAS, while an ACTH increase > 50 achieved 100% specificity. Moreover, the combination of serum cortisol suppression > 50% and an ACTH increase > 35% in both tests only occurred in Cushing's disease. Pituitary magnetic resonance imaging identified 100% of macroadenomas and 59.4% of microadenomas in patients with CD. Among 10 patients that underwent bilateral inferior petrosal sinus sampling, a central-to-peripheral ACTH gradient > 3 after CRH or DDAVP had 90% sensitivity and 100% specificity for Cushing's disease.

The diagnosis of Cushing's syndrome: an Endocrine Society Clinical Practice Guideline

OBJECTIVE

The objective of the study was to develop clinical practice guidelines for the diagnosis of Cushing's syndrome.

PARTICIPANTS

The Task Force included a chair, selected by the Clinical Guidelines Subcommittee (CGS) of The Endocrine Society, five additional experts, a methodologist, and a medical writer. The Task Force received no corporate funding or remuneration.

CONSENSUS PROCESS

Consensus was guided by systematic reviews of evidence and discussions. The guidelines were reviewed and approved sequentially by The Endocrine Society's CGS and Clinical Affairs Core Committee, members responding to a web posting, and The Endocrine Society Council. At each stage the Task Force incorporated needed changes in response to written comments.

CONCLUSIONS

After excluding exogenous glucocorticoid use, we recommend testing for Cushing's syndrome in patients with multiple and progressive features compatible with the syndrome, particularly those with a high discriminatory value, and patients with adrenal incidentaloma. We recommend initial use of one test with high diagnostic accuracy (urine cortisol, late night salivary cortisol, 1 mg overnight or 2 mg 48-h dexamethasone suppression test). We recommend that patients with an abnormal result see an endocrinologist and undergo a second test, either one of the above or, in some cases, a serum midnight cortisol or dexamethasone-CRH test. Patients with concordant abnormal results should undergo testing for the cause of Cushing's syndrome. Patients with concordant normal results should not undergo further evaluation. We recommend additional testing in patients with discordant results, normal responses suspected of cyclic hypercortisolism, or initially normal responses who accumulate additional features over time.

Late-night salivary cortisol measurement in the diagnosis of Cushing's syndrome

Making a definite diagnosis of Cushing's syndrome is a challenging problem. Unsuspected Cushing's syndrome occurs in 2-3% of patients with poorly controlled diabetes, 0.5-1% with hypertension, 6-9% with incidental adrenal masses, and 11% with unexplained osteoporosis and vertebral fractures. The increasing recognition of this syndrome highlights the need for a simple, sensitive, and specific diagnostic test. Patients with Cushing's syndrome consistently do not reach a normal nadir of cortisol secretion at night. The measurement of late-night salivary cortisol levels might, therefore, provide a new diagnostic approach for this disorder. Salivary cortisol concentrations reflect those of active free cortisol in plasma and saliva samples can easily be obtained in a nonstressful environment (e.g. at home). Late-night salivary cortisol measurement yields excellent overall diagnostic accuracy for Cushing's syndrome, with a sensitivity of 92-100% and a specificity of 93-100%. Several factors can, however, make interpretation of results difficult; these factors include disturbed sleep-wake cycles, contamination of samples (particularly by topical corticosteroids), and illnesses known to cause physiologic activation of the pituitary-adrenal axis. In this Review, we discuss the methods and value of measuring salivary cortisol for the diagnosis of Cushing's syndrome, and put forward some recommendations to maximize accuracy of results.

Dynamic testing in Cushing's syndrome

Endogenous Cushing's syndrome (CS) results from chronic exposure to excess glucocorticoids. CS can be ACTH-dependent, caused by ACTH-secreting pituitary or ectopic tumours, or ACTH-independent, caused by cortisol-secreting adrenal tumours. CS can be an extremely difficult diagnosis to make, and assessment will include clinical, biochemical and radiological evaluation. Several screening tests are used for the confirmation of hyper-cortisolaemia and its differentiation from other, more frequent, clinical abnormalities, such as simple obesity, hypertension, depression etc. Other dynamic tests are useful for establishing the aetiology. We have reviewed the current literature on the diagnosis of CS, and based on these data and our own experience, suggest the most useful tests and diagnostic criteria to be used. We conclude that even though laboratory testing is a fundamental part of the investigation of patients with CS, the interpretation of the tests should always be performed with extreme care, as none of the tests has proven fully capable of distinguishing all cases of CS. The biochemical results should be interpreted jointly with the clinical aspects and the radiology findings in a probabilistic matrix, and not as part of a uniform algorithm.

"Subclinical Cushing's syndrome" is not subclinical: improvement after adrenalectomy in 9 patients

BACKGROUND

A subgroup of patients with adrenal cortisol hypersecretion fails to meet the biochemical criteria for Cushing's syndrome. Appropriate therapy for this entity, subclinical Cushing's syndrome (subclinical CS), is unclear. We examined outcomes for patients who underwent unilateral adrenalectomy for subclinical CS.

METHODS

Between 2003 and 2006, all patients who underwent adrenalectomy for cortisol hypersecretion caused by an adrenal mass were examined. We analyzed biochemical, metabolic, and clinical outcomes.

RESULTS

Overall, 24 patients underwent adrenalectomy for adrenal cortisol hypersecretion, of which 9 were found to have subclinical CS. Median serum cortisol was 2.0 microg/dL (range, 1.1-6.1) after 1-mg overnight dexamethasone suppression testing. Suspicious clinical findings on preoperative examination included skin bruising, unexplained weight gain, proximal muscle weakness, abnormal fat pads, skin thinning, fatigue, and facial plethora. During a median follow-up period of 5 months (range, 1-30 months), all 8 patients with easy bruising noted resolution postoperatively. Fatigue improved in 4 of 5 patients, muscle weakness in 6 of 8 patients, and weight in 7 of 9 patients, with a median body mass index change of -2.0 kg/m(2) (range, -7.1 to +0.5 kg/m(2)).

CONCLUSION

Adrenalectomy improves clinical and metabolic parameters for many patients with subclinical CS.

Screening and diagnosis of Cushing's syndrome

Cushing's syndrome (CS) results from sustained pathologic hypercortisolism. The clinical features are variable and the most specific features for CS include abnormal fat distribution, particularly in the supraclavicular and temporal fossae, proximal muscle weakness, wide purple striae, and decreased linear growth with continued weight gain in a child. Clinical presentation of CS can be florid and in this case the diagnosis is usually straightforward. However, the diagnosis can be difficult particularly in states of mild or cyclical or periodical hypercortisolism. Several tests based on the understanding of the physiologic characteristics of the hypothalamic-pituitary-adrenal axis have been used extensively to confirm the diagnosis of Cushing's syndrome, but none has proven fully capable of distinguishing all cases of CS from normal and/or pseudo-Cushing individuals. Three first-line diagnostic tests are currently used to screen for CS: measurement of free cortisol in 24-hour urine (UFC), cortisol suppressibility by low doses of dexamethasone (DST), and assessment of cortisol circadian rhythm using late-night serum and/or salivary cortisol. This paper discusses the effectiveness regarding best cut-off values, the sensitivity and the specificity of these tests to screen for CS. Late-night salivary cortisol appears to be the most useful screening test. UFC and DST should be performed to provide further confirmation of the diagnosis.

Specificity of first-line tests for the diagnosis of Cushing's syndrome: assessment in a large series

CONTEXT

The diagnosis of Cushing's syndrome requires highly sensitive screening tests. Therefore, diagnostic cutoffs have been lowered to maximize sensitivity and identify all patients. However, few studies have investigated the impact of these refinements on the specificity of first-line tests.

OBJECTIVE

The aim of the study was the assessment of the specificity of three widely used screening tests in a large series of Cushing's syndrome suspects referred to our endocrine service.

PATIENTS

We retrospectively reviewed the results of urinary free cortisol (UFC), 1-mg dexamethasone suppression test [overnight suppression test (OST)], and serum cortisol at midnight in 3,461, 357, and 864 patients, respectively, with clinical features suggestive of Cushing's syndrome but in whom this diagnosis was subsequently excluded.

RESULTS

UFC and OST at the 5-microg/dl cutoff exhibited the highest specificities [91% (95% confidence intervals [CI] 90.2-92.1%) and 97% (95% CI 96.3-98.5%), respectively]. Conversely, midnight serum cortisol yielded 87% (95% CI 84.3-91.1%) specificity only with the 7.5-microg/dl cutoff, whereas the 1.8-microg/dl threshold resulted in an unacceptably high proportion of false positives at only 20% specificity (95% CI 16.0-24.4%). Gender and age may lead to misleading results in all three screening tests.

CONCLUSIONS

Specificity of tests for Cushing's syndrome varies considerably, with OST and UFC presenting the best performances, and circadian rhythm appearing heavily impaired by lowering of diagnostic cutoffs. Indeed, the vast majority of individuals in our series presented midnight serum cortisol values greater than 1.8 microg/dl; thus, caution has to be exercised when this criterion is used to exclude Cushing's syndrome.

Chronobiology in the endocrine system

Biological signaling occurs in a complex web with participation and interaction of the central nervous system, the autonomous nervous system, the endocrine glands, peripheral endocrine tissues including the intestinal tract and adipose tissue, and the immune system. All of these show an intricate time structure with rhythms and pulsatile variations in multiple frequencies. Circadian (about 24-hour) and circannual (about 1-year) rhythms are kept in step with the cyclic environmental surrounding by the timing and length of the daily light span. Rhythmicity of many endocrine variables is essential for their efficacy and, even in some instances, for the qualitative nature of their effects. Indeed, the continuous administration of certain hormones and their synthetic analogues may show substantially different effects than expected. In the design of drug-delivery systems and treatment schedules involving directly or indirectly the endocrine system, consideration of the human time organization is essential. A large amount of information on the endocrine time structure has accumulated, some of which is discussed in this review.

Cushing’s syndrome in a clinic population with diabetes

BACKGROUND

A recent report has suggested that occult Cushing's syndrome (CS) may be present in a significant number of patients with type 2 diabetes mellitus. The aim of this study was to determine whether any patients in our clinic population with diabetes had this condition.

METHODS

One hundred and seventy-one consecutive overweight attendees at the diabetic clinic were enrolled in a study to assess the presence of occult CS. The initial screen was with the 1 mg overnight dexamethasone suppression test and follow-up testing, where indicated was with a 24 h collection for urine-free cortisol.

RESULTS

Thirty-one of 171 patients had a positive result from the overnight dexamethasone suppression test. Follow-up testing with 24 h urine-free cortisol reduced the number of patients with positive results to 3. Two of these were shown to have alcoholic pseudo-CS. The third patient has had several high urine-free cortisol results, in the presence of normal scans of pituitary and adrenals. He has no stigmata of CS and is being observed.

CONCLUSION

Based on the results of our study, there would appear to be little value in screening type 2 diabetics for CS, in the absence of clinical suspicion.

Adrenal Masses in the Cancer Patient: Surveillance or Excision

An increasing number of patients with a history of solid organ malignancy now undergo surveillance imaging as part of their follow-up or for evaluation of other conditions. This imaging has led to both greater identification of asymptomatic adrenal masses and subsequent confusion among clinicians regarding the evaluation and treatment. Although established algorithms exist for treating such "incidentalomas" in otherwise healthy patients, the most effective way to do so in patients with known prior or concurrent malignancies is unclear. In this review, we explore methods of biochemical testing in such patients and discuss the role of imaging techniques in their ability to differentiate benign versus malignant lesions. In this population, we examine the increasing use of biopsy and discuss current data on both surveillance and resection of lesions based on their identity. Finally, we propose an algorithm to aid the clinician in evaluating and treating these complex patients efficiently.

Diagnostic Value of Biochemical Parameters in the Differential Diagnosis of an Adrenal Mass

In patients with an adrenal mass, hormonally active tumors including pheochromocytomas as well as aldosterone- and cortisol-secreting adenomas need to be considered. Several studies have demonstrated that metanephrines, which are the metabolites of catecholamines, are reliable parameters for the diagnosis of pheochromocytoma. In patients with an adrenal mass, we found plasma metanephrines, measured by a newly available radioimmunoassay, to be highly sensitive and specific for pheochromocytomas, with a better accuracy than any other biochemical parameter. The plasma aldosterone concentration (PAC) to plasma renin activity (PRA) ratio is an established screening tool for primary hyperaldosteronism. However, determination of active renin concentration (ARC) in contrast to PRA may offer advantages in regard to processing and standardization. We found a PAC to ARC ratio of >62 in patients with PAC levels>200 ng/L to be a reliable screening method for primary hyperaldosteronism in patients with adrenal masses. The screening for hypercortisolism relies on excess urinary cortisol secretion, loss of the physiological feedback during dexamethasone challenge, and loss of the circadian rhythm. Because urinary-free cortisol may not identify subclinical Cushing's syndrome, in which hypercortisolism is still mild, the 1-mg dexamethasone suppression test has been recommended in all patients with incidentally detected masses. Alternatively, late-night cortisol levels in saliva have been found to have a high sensitivity and specificity for the diagnosis of Cushing's syndrome. In summary, in patients with an adrenal mass, hormonally active adrenal tumors can be excluded with high certainty using a few highly reliable biochemical parameters.

Cushing's syndrome

Cushing's syndrome results from lengthy and inappropriate exposure to excessive glucocorticoids. Untreated, it has significant morbidity and mortality. The syndrome remains a challenge to diagnose and manage. Here, we review the current understanding of pathogenesis, clinical features, diagnostic, and differential diagnostic approaches. We provide diagnostic algorithms and recommendations for management.

Endogenous subclinical hypercortisolism: Diagnostic uncertainties and clinical implications

Subclinical hypercortisolism (SH) is a newly characterized hormonal disorder that is almost exclusively detected in the context of incidentally discovered adrenal masses. The diagnostic criteria used for the definition of this condition are at present controversial. Amongst the various tests used for the detection of this abnormality (dexamethasone suppression, urinary free cortisol, ACTH levels, midnight serum or salivary cortisol concentrations, ACTH responses to CRH stimulation), the dexamethasone suppression tests (DST) seem to better accomplish the task of unmasking subtle abnormalities of cortisol secretion. Several versions of DST have been used: the 1-mg overnight, the 3-mg overnight and the classical 2-day low-dose DST. This latter test has the theoretical advantage that, by more efficiently suppressing pituitary ACTH secretion, it may provide a measure of the residual (ie non- ACTH-dependent) cortisol secretion from the adrenal mass. In this way, post-dexamethasone cortisol concentrations may quantify the degree of autonomous cortisol hypersecretion. In fact, post-dexamethasone cortisol concentrations have a negative correlation with basal ACTH levels and a positive correlation with midnight cortisol concentrations as well as the size of the incidentally discovered adrenal mass. Most of the existing data indicate that SH detected in the context of adrenal incidentalomas may have some clinically significant implications. In fact, patients with higher post-dexamethasone cortisol concentrations demonstrate higher lipid levels and lower bone mass densities. It has also been suggested that SH may be responsible for biochemical and phenotypic changes reminiscent of the metabolic syndrome. In summary, SH does exist and is associated with a negative impact in patients' health; however, hormonal cut-off criteria for decision-making remain to be defined.

Differential diagnosis and imaging in Cushing's syndrome

Establishing the cause of Cushing's syndrome (CS) is one of the most challenging processes in clinical endocrinology. Biochemical testing, including measurement of plasma adrenocorticotropin (ACTH), high-dose dexamethasone suppression, and corticotropin-releasing hormone stimulation testing, is integral to the differential diagnosis. No existing test has sufficient diagnostic accuracy when used alone, however. The adjunctive use of focused imaging, including CT, MRI, and nuclear imaging modalities, often can provide a diagnosis. In patients with ACTH-dependent CS, bilateral inferior petrosal sinus sampling can facilitate a diagnosis in those with discrepant clinical features, biochemistry, or imaging. This article focuses on current biochemical and radiologic strategies for the differential diagnosis of CS.

The clinically inapparent adrenal mass: update in diagnosis and management

Clinically inapparent adrenal masses are incidentally detected after imaging studies conducted for reasons other than the evaluation of the adrenal glands. They have frequently been referred to as adrenal incidentalomas. In preparation for a National Institutes of Health State-of-the-Science Conference on this topic, extensive literature research, including Medline, BIOSIS, and Embase between 1966 and July 2002, as well as references of published metaanalyses and selected review articles identified more than 5400 citations. Based on 699 articles that were retrieved for further examination, we provide a comprehensive update of the diagnostic and therapeutic approaches focusing on endocrine and radiological features as well as surgical options. In addition, we present recent developments in the discovery of tumor markers, endocrine testing for subclinical disease including autonomous glucocorticoid hypersecretion and silent pheochromocytoma, novel imaging techniques, and minimally invasive surgery. Based on the statements of the conference, the available literature, and ongoing studies, our aim is to provide practical recommendations for the management of this common entity and to highlight areas for future studies and research.