Pitfalls in the diagnosis of Cushing's syndrome

Accuracy of the 10 μg desmopressin test for differential diagnosis of Cushing syndrome: a systematic review and meta-analysis

We evaluated the accuracy of the 10 μg desmopressin test in differentiating Cushing disease (CD) from non-neoplastic hypercortisolism (NNH) and ectopic ACTH syndrome (EAS). A systematic review of studies on diagnostic test accuracy in patients with CD, NNH, or EAS subjected to the desmopressin test obtained from LILACS, PubMed, EMBASE, and CENTRAL databases was performed. Two reviewers independently selected the studies, assessed the risk of bias, and extracted the data. Hierarchical and bivariate models on Stata software were used for meta-analytical summaries. The certainty of evidence was measured using the GRADE (Grading of Recommendations Assessment, Development, and Evaluation Working Group) approach. In total, 14 studies were included: 3 studies on differentiated CD versus NNH and 11 studies on differentiated CD versus EAS. Considering ΔACTH in 8 studies involving 429 patients, the pooled sensitivity for distinguishing CD from EAS was 0.85 (95% confidence interval [CI]: 0.80-0.89, I2 = 17.6%) and specificity was 0.64 (95% CI: 0.49-0.76, I2 = 9.46%). Regarding Δcortisol in 6 studies involving 233 participants, the sensitivity for distinguishing CD from EAS was 0.81 (95% CI: 0.74-0.87, I2 = 7.98%) and specificity was 0.80 (95% CI: 0.61-0.91, I2 = 12.89%). The sensitivity and specificity of the combination of ΔACTH > 35% and Δcortisol > 20% in 5 studies involving 511 participants were 0.88 (95% CI: 0.79-0.93, I2 = 35%) and 0.74 (95% CI: 0.55-0.87, I2 = 27%), respectively. The pooled sensitivity for distinguishing CD from NNH in 3 studies involving 170 participants was 0.88 (95% CI: 0.79-0.93) and the specificity was 0.94 (95% CI: 0.86-0.97). Based on the desmopressin test for differentiating CD from EAS, considering ΔACTH, Δcortisol, or both percent increments, 15%, 19%, or 20% of patients with CD, respectively, would be incorrectly classified as having EAS. For CD versus NNH, 11% of patients with CD would be falsely diagnosed as having NNH, whereas 7% of patients with NNH would be falsely diagnosed as having CD. However, in all hierarchical plots, the prediction intervals were considerably wider than the confidence intervals. This indicates low confidence in the estimated accuracy, and the true accuracy is likely to be different.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=85634, identifier CRD42018085634; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=68317, identifier CRD42017068317.

[Cyclic Cushing's syndrome: difficulties of diagnostic search and choice of treatment tactics. A clinical case]

Cyclic Cushing's syndrome is a pathological condition characterized by alternating periods of excessive cortisol secretion with corresponding clinical manifestations and periods of spontaneous remission of the disease.To diagnose Cyclic Cushing's syndrome it is necessary to record at least three episodes of excessive cortisol secretion alternating with periods of normalization of its production.In most cases, this pathology is diagnosed in patients with ACTH-secreting pituitary tumor, however, there are rare cases of cyclic hypercorticism with ectopic ACTH secretion by tumors of different localization and without verification of pathological hormonal secretion focus. In addition, cyclic hyperproduction of cortisol can be also observed in ACTH-independent Cushing's syndrome associated with the presence of corticosteroma or adrenal hyperplasia. The exact causes and mechanisms of the cyclic hypercorticism are currently insufficiently studied.Due to the atypical course of the disease, the unpredictability of the occurrence of a new «cycle», the variability of its duration and manifestations (not only in different patients, but also in the same patient), verification of the diagnosis and determination of treatment tactics may be difficult in the daily practice of specialists, and the prevalence of this condition can be undervalued.

Simultaneous Measurement of Cortisol, Cortisone, Dexamethasone and Additional Exogenous Corticosteroids by Rapid and Sensitive LC-MS/MS Analysis

The simultaneous measurement of dexamethasone and cortisol has proven the ability to increase the diagnostic performance of the overnight dexamethasone-suppression test. Furthermore, the therapeutic drug monitoring of administered corticosteroid drugs could represent a crucial tool for investigating unexpected variations of steroid hormones' circulating levels. In this work, an LC-MS/MS method for the quantification of cortisol, cortisone, dexamethasone and six additional exogenous corticosteroids in the serum/plasma matrix was developed and validated in compliance with the ISO/IEC requirements. To assess the efficiency of the validated method, serum samples of 75 patients undergoing the dexamethasone-suppression test and 21 plasma samples of patients under immunosuppressive treatment after kidney transplant were analyzed. In all dexamethasone-suppression test samples, it was possible to measure the circulating levels of cortisol, cortisone and dexamethasone. Concentrations of the latter were for all tested patients above the proposed cutoff for the dexamethasone-suppression test's results, and the cortisol concentrations showed good correlation with the ones measured by routine immunometric analysis, therefore confirming the screening outcome for all enrolled patients. Prednisone was detected and quantified in all enrolled patients, confirming the use of such a corticosteroid for immunosuppressive therapy. Thanks to these two applications, we proved the overall performance of the developed LC-MS/MS method for four target analytes. The future implementation of such an analytical tool in the clinical biochemistry laboratory's routine will guarantee a single and versatile tool for simultaneously monitoring dexamethasone-suppression-test results and corticosteroid drugs' administration.

Machine Learning Models for Classification of Cushing's Syndrome Using Retrospective Data

Accurate classification of Cushing's Syndrome (CS) plays a critical role in providing the early and correct diagnosis of CS that may facilitate treatment and improve patient outcomes. Diagnosis of CS is a complex process, which requires careful and concurrent interpretation of signs and symptoms, multiple biochemical test results, and findings of medical imaging by physicians with a high degree of specialty and knowledge to make correct judgments. In this article, we explore the state of the art machine learning algorithms to demonstrate their potential as a clinical decision support system to analyze and classify CS to facilitate the diagnosis, prognosis, and treatment of CS. Prominent algorithms are compared using nested cross-validation and various class comparison strategies including multiclass, one vs. all, and one vs. one binary classification. Our findings show that Random Forest (RF) algorithm is most suitable for the classification of CS. We demonstrate that the proposed approach can classify CS with an average accuracy of 92% and an average F1 score of 91.5%, depending on the class comparison strategy and selected features. RF-based one vs. all binary classification model achieves sensitivity of 97.6%, precision of 91.1%, and specificity of 87.1% to discriminate CS from non-CS on the test dataset. RF-based multiclass classification model achieves average per class sensitivity of 91.8%, average per class specificity of 97.1%, and average per class precision of 92.1% to classify different subtypes of CS on the test dataset. Clinical performance evaluation suggests that the developed models can help improve physicians' judgment in diagnosing CS.

Method-Specific Cortisol and Dexamethasone Thresholds Increase Clinical Specificity of the Dexamethasone Suppression Test for Cushing Syndrome

BACKGROUND

The dexamethasone suppression test (DST) is the recommended first-tier test for suspected Cushing syndrome (CS). Missed dexamethasone intake or insufficient dexamethasone serum exposure may yield false positive results. Quantification of serum dexamethasone in DST samples may therefore improve test performance.

METHODS

Simultaneous quantification of dexamethasone and cortisol by liquid chromatography-tandem mass spectrometry in 400 DST serum samples (100 overt CS, 200 excluded CS, 100 adrenal incidentalomas with (possible) autonomous cortisol secretion, AI-ACS) randomly selected within the indication groups. The 2.5th percentile of dexamethasone in patients with excluded CS was considered the lower limit of normal (LLN).

RESULTS

Serum dexamethasone varied from undetectable to 20.2 ng/mL with a median of 4.8 ng/mL (95% CI 4.5-5.1 ng/mL). Dexamethasone was undetectable in only 16 patients (4%), suggesting non-compliance. The dexamethasone LLN was 1.8 ng/mL (4.6 nmol/L). Decreased glomerular filtration rate and diabetes mellitus were associated with higher serum dexamethasone concentration, while body mass index, sex, age, nicotine, and oral contraceptives had no significant effect. By excluding the 27 samples with dexamethasone <LLN and applying the method-specific cortisol cutoff of 2.4 µg/dL (66 nmol/L) to samples with suspected CS, the clinical specificity for CS increased from 67.5% to 92.4% while preserving 100% clinical sensitivity. Among 100 AI-ACS samples (defined by immunoassay), 4 samples had dexamethasone <1.8 ng/mL and 14 samples had cortisol <2.4 µg/dL, which excluded autonomous cortisol secretion.

CONCLUSIONS

Quantification of dexamethasone and method-specific cortisol cutoffs in DST samples may reduce the false positive rate and lower the proportion of patients requiring further workup.

Persistent Cushing's Disease after Transsphenoidal Surgery: Challenges and Solutions

Transsphenoidal surgery remains the primary treatment for Cushing's disease (CD). However, despite the vast improvements in pituitary surgery, successful treatment of CD remains a great challenge. Although selective transsphenoidal removal of the pituitary tumor is a safe and effective procedure, the disease persists in around 22% of CD patients due to incomplete tumor resection. The persistence of hypercortisolism after pituitary surgery may also be the consequence of a misdiagnosis, as can occur in case of ectopic ACTH secretion or pseudo-Cushing. Considering the elevated mortality and morbidity characterizing the disease, a multidisciplinary approach is needed to minimize potential pitfalls occurring during the diagnosis, avoid surgical failure and provide the best care in those patients who have undergone unsuccessful surgery. In this review, we analyze the factors that could predict remission or persistence of CD after pituitary surgery and revise the therapeutic options in case of surgical failure.

Pulmonary embolism as the presenting symptom and a confounder in ACTH-secreting bronchial carcinoid

Ectopic ACTH-secreting pulmonary neuroendocrine tumors are rare and account for less than 5% of endogenous Cushing’s syndrome cases. We describe an unusual case of metastatic bronchial carcinoid tumor in a young woman presenting with unprovoked pulmonary emboli, which initially prevented the detection of the primary tumor on imaging. The source of ectopic ACTH was ultimately localized by a Gallium-DOTATATE scan, which demonstrated increased tracer uptake in a right middle lobe lung nodule and multiple liver nodules. The histological diagnosis was established based on a core biopsy of a hepatic lesion and the patient was started on a glucocorticoid receptor antagonist and a somatostatin analog. This case illustrates that hypercogulability can further aggravate the diagnostic challenges in ectopic ACTH syndrome. We discuss the literature on the current diagnosis and management strategies for ectopic ACTH syndrome.

Hormonal aggressiveness according to the expression of cellular markers in corticotroph adenomas

PURPOSE

The molecular mechanisms underlying tumor growth in Cushing's disease (CD) still remain a challenge. Moreover, clinical manifestations of CD may vary depending on hormonal activity; however, factors involved in the hormonal aggressiveness of adrenocorticotropic hormone (ACTH)-secreting pituitary tumors have not been fully clarified. We investigated the association between the expression of cellular markers regarding pituitary tumor progression and initial or postoperative hormone levels in patients with CD.

METHODS

Tumor tissues from 28 corticotroph adenomas (female 26, male 2, mean age 39.21 ± 10.39 years) were subject to immunohistochemical study using the following antibodies: pituitary tumor-transforming gene 1 (PTTG1), cyclin D1, p16, p27, brahma related-gene 1 (Brg1), and Ki-67. We then analyzed the relationship between each cellular marker expression and hormone levels, including 24 h urinary free cortisol (UFC), plasma ACTH, and serum cortisol.

RESULTS

PTTG1 and Ki-67 were expressed in 100% and 50% of patients, respectively. However, the levels did not reflect initial hormonal activity. The cyclin D1-negative group showed higher serum cortisol levels compared to the cyclin D1-positive group (p = 0.01). The 24 h UFC levels were significantly higher in the p27-negative group than in the p27-positive group (p = 0.04), whereas the Brg1-positive group revealed higher serum cortisol levels than in the Brg1-negative group (p = 0.02).

CONCLUSIONS

Although PTTG1 and Ki-67 play an essential role in developing ACTH-secreting tumors, cyclin D1, p27, and Brg1 may be better biomarkers to determine hormonal aggressiveness of the tumor. Further research is needed to understand the influence of cellular markers on hormonal activity in CD.

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.

Cushing's Syndrome Due to CRH and ACTH Co-secreting Pancreatic Tumor--Presentation of a New Case Focusing on Diagnostic Pitfalls

Cushing's syndrome (CS) due to a corticotropin-releasing hormone (CRH) and adrenocorticotropin hormone (ACTH) co-secreting tumor is very rare, and diagnosis can be difficult. We describe a case of CS caused by ectopic CRH and ACTH production from a pancreatic neuroendocrine tumor (pNET) and discuss possible pitfalls in the diagnosis. A 48-year-old woman presented with gradual increase in body weight, muscle weakness, and difficult to control hypertension. Laboratory and imaging investigations revealed ACTH-dependent hypercortisolemia and a 3-cm mass at the head of the pancreas. The patient underwent partial pancreatoduodenectomy. Histological examination revealed a well-differentiated pNET, expressing both CRH and ACTH. After a follow-up period of 18 months, she remains asymptomatic with no metastatic disease. This is the fourth case report of CS in adults due to an ectopic ACTH- and CRH-secreting pNET. Co-secretion of ACTH and CRH by the same tumor may cause diagnostic problems since investigation depends on which of the two hormones is secreted in greater amounts. Measurement of plasma CRH may help in establishing the diagnosis, especially in patients in whom endocrine tests are indicative of ectopic CS, whereas imaging findings are suggestive of pituitary hyperplasia.

Usefulness of dynamic MRI enhancement measures for the diagnosis of ACTH-producing pituitary adenomas

PURPOSE

The distinction between corticotropin (ACTH)-producing pituitary adenomas and occult ectopic ACTH neoplasms is a challenge and frequently complicated by the detection of nonfunctioning pituitary adenomas on dynamic magnetic resonance imaging (DMRI). Herein, we explored quantitative differences in DMRI measures from ACTH-producing pituitary adenomas.

MATERIALS AND METHODS

Fifty-five patients with pathology confirmed ACTH-producing and 44 with nonfunctioning pituitary adenomas were analysed in this retrospective pilot study. The intensities of adenomas and of adjacent pituitary tissue were measured by drawing a region of interest. Time-intensity curves were then constructed, and quantitative analysis included: enhancement time, enhancement peak and prepeak slope (PPS). Multivariable logistic analysis and receiver operating characteristic curves (ROC) were used to evaluate the parameters.

RESULTS

Quantitative analysis showed that tumour PPS in ACTH-producing adenomas was markedly lower than that in nonfunctioning adenomas (P = 0·0042) and that the PPS of the adjacent pituitary gland was not different (P = 0·2441). The PPS was >3·0 in 59·1% of nonfunctioning adenomas and ≤3·0 in 69·1% of ACTH-producing adenomas (P = 0·0049). Logistic analysis revealed lower tumour PPS levels (P = 0·0123, OR 1·24, 95% CI: 1·05-1·52) were associated with ACTH-producing adenomas. The optimal PPS cut-off determined by ROC analysis was 2·89, with a sensitivity of 69% and specificity of 70%. No significant difference was found between the two groups in enhancement time or enhancement peak.

CONCLUSION

Enhancement parameters in DMRI can help distinguishing ACTH producing from nonfunctioning pituitary adenomas, which could be useful in the differential diagnosis between ACTH-producing pituitary adenomas and ectopic ACTH syndrome complicated with nonfunctioning pituitary adenoma.

Managing Cushing's disease: the state of the art

Cushing's disease is a rare chronic disease caused by a pituitary adenoma, which leads to excess secretion of adrenocorticotropic hormone (ACTH). The over-production of ACTH leads to hyperstimulation of the adrenal glands and a chronic excess of cortisol, resulting in the signs and symptoms of a severe clinical state (Cushing's syndrome) that leads to significant morbidity, negative impacts on the patient's quality of life, and, if untreated, increased mortality. The management of patients with Cushing's disease is complicated by the heterogeneity of the condition, with signs and symptoms that overlap with those of other diseases, and high subclinical incidence rates. Controversies surrounding the tests used for screening and identifying patients with Cushing's disease add to the challenge of patient management. Surgical intervention to remove the adenoma is the first-line treatment for patients with Cushing's disease, but medical therapies are useful in patients who relapse or are unsuitable for surgery. The recent introduction of pasireotide, the first pituitary-directed medical therapy, expands the number of treatment options available for patients with Cushing's disease. This state-of-the-art review aims to provide an overview of the most recent scientific research and clinical information regarding Cushing's disease. Continuing research into improving the diagnosis and treatment of Cushing's disease will help to optimize patient management.

Performance of salivary cortisol in the diagnosis of Cushing's syndrome, adrenal incidentaloma, and adrenal insufficiency

OBJECTIVE

Salivary cortisol has recently been suggested for studies on the hypothalamic-pituitary-adrenal (HPA) axis. The lack of circadian rhythm is a marker of Cushing's syndrome (CS), and some authors have reported that low salivary cortisol levels may be a marker of adrenal insufficiency. The aim of our study was to define the role of salivary cortisol in specific diagnostic settings of HPA axis disease.

SUBJECTS AND METHODS

We analyzed morning salivary cortisol (MSC) and late-night salivary CORTISOL (LNSC) levels in 406 SUBJECTS: 52 patients with Cushing's disease (CD), 13 with ectopic CS, 17 with adrenal CS, 27 with CD in remission (a mean follow-up of 66±39 months), 45 with adrenal incidentaloma, 73 assessed as having CS and then ruled out for endogenous hypercortisolism, 75 with adrenal insufficiency, and 104 healthy subjects.

RESULTS

A LNSC value above 5.24  ng/ml differentiated CS patients from controls with high sensitivity (96.3%) and specificity (97.1%); we found higher LNSC levels in ectopic CS patients than in CD patients. We found no difference in MSC and LNSC levels between patients with CD in remission and healthy subjects. Both MSC and LNSC levels were higher in patients with adrenal incidentaloma than in healthy controls. A MSC value below 2.65 ng/ml distinguished patients with adrenal insufficiency from controls with high sensitivity (97.1%) and specificity (93.3%).

CONCLUSIONS

Salivary cortisol is a useful tool to assess endogenous cortisol excess or adrenal insufficiency and to evaluate stable CD in remission.

Severe ectopic cushing syndrome caused by adenoid cystic carcinoma of a salivary gland

OBJECTIVE

We present a rare case of Cushing syndrome due to ectopic adrenocorticotropic hormone (ACTH) secretion (EAS). To our knowledge only two similar cases have been previously reported.

METHODS

This is a case report of EAS by a metastatic lingual adenoid cystic carcinoma (ACC).

RESULTS

The patient was diagnosed of a Cushing syndrome caused by tumoral EAS two years after initial cancer diagnosis. Clinical presentation included asthenia, insomnia, hypertension, acne, and hyperpigmentation developing in a period of two months. Laboratory and imaging testing revealed hypokalemic metabolic alkalosis, hypercortisolemia, high ACTH, nonsuppresion by 8 mg dexamethasone, and a normal pituitary magnetic resonance imaging (MRI). With a high clinical suspicion of EAS, combined medical treatment was started but was unsuccessful. Bilateral adrenalectomy could not be performed given the patient's rapid deterioration. Immunostained tissue from the original tumor was positive for synaptophysin.

CONCLUSION

This rare case of EAS illustrates the challenge that this condition may confer regarding diagnosis and management.

A rare case of Cushing syndrome by cyclic ectopic-ACTH

ACTH-dependent Cushing syndrome (CS) due to ectopic ACTH production is most times difficult to manage. The identification of the source of ACTH may take many years. Surgery or chemotherapy for the primary tumor is not always possible. Control of Cushing symptoms is many times achieved using medication, or bilateral adrenalectomy in refractory cases. This case presents a Brazilian male who showed severe hypertension, mood changes, muscle weakness, darkening of skin, and increased abdominal fat. An investigation for Cushing syndrome was carried out and, after a four-year follow-up, a carotid glomus tumor (chemodectoma) was confirmed, a rare ectopic ACTH-producing tumor. Besides, the patient presented cyclic Cushing syndrome that was exacerbated by diverticulitis episodes. This case presents interesting pitfalls on diagnosis and management of ACTH-dependent CS. This is the only report of a chemodectoma that produced ACTH in the literature.

Disappearance of pituitary macro adenoma with combination of ketoconazole and cabergoline treatment: an unusual case of Cushing's syndrome with interesting findings

Cushing syndrome is associated with significant morbidity and mortality if left untreated because of associated metabolic and cardiovascular complications. An extremely ill patient with Cushing's syndrome caused by adrenocorticotropic hormone producing pituitary macro adenoma responded dramatically to ketoconazole and cabergoline treatment. His 4 month long medical treatment resulted in improvement of hypercotisolism clinically and biochemically and in complete disappearance of pituitary macro adenoma without any surgical intervention.

Dexamethasone suppression test: development of a method for simultaneous determination of cortisol and dexamethasone in human plasma by liquid chromatography/tandem mass spectrometry

BACKGROUND

Dexamethasone is a synthetic glucocorticoid and is analogous to cortisol. It is used in the low-dose overnight dexamethasone suppression test (LDODST) to diagnose hypercortisolism in patients suspected to be suffering from Cushing's syndrome (CS). Measuring plasma dexamethasone in conjunction with measuring the amount of cortisol following the LDODST may allow clinicians to improve the diagnosis of CS.

METHODS

Plasma samples were cleaned up by solid-phase extraction before analysis. Liquid chromatographic separation was carried out under reversed-phase conditions prior to detection by tandem mass spectrometry. The analytes were determined in the presence of deuterated internal standards cortisol-d4 and dexamethasone-d4.

RESULTS

Limit of quantitation (LOQ) was 1.89 nmol/L for dexamethasone and <0.02 μmol/L for cortisol. Recoveries of both analytes ranged from 80.2% to 114.4%. Intra- and interassay coefficients of variation were <15%. The concentration of dexamethasone and cortisol was determined in 62 patients after performing LDODST. Dexamethasone concentrations ranged from 3.0 to 21.5 nmol/L (median 7.4 nmol/L) for 57 of these samples. For five patients the concentration was <LOQ. Cortisol concentrations were <0.08 μmol/L (median 0.037 μmol/L, n = 54) except for eight patients (>0.22 μmol/L).

CONCLUSIONS

A method for the simultaneous measurement of dexamethasone and cortisol in human plasma by liquid chromatography/tandem mass spectrometry has been developed and validated. The method is suitable for controlling the compliance to the LDODST and for determining the cortisol plasma concentration after the test. The interpretation of LDODSTs was improved by the simultaneous determination of both analytes.

Intraoperative multiple-staged resection and tumor tissue identification using frozen sections provide the best result for the accurate localization and complete resection of tumors in Cushing's disease

The treatment of choice in Cushing's disease (CD) is surgical removal; however, most tumors are too small to be detected. The objective was to establish a method to achieve the complete removal of tumors on the basis of the results of high-resolution magnetic resonance imaging (MRI), inferior petrosal sinus sampling (IPSS), and a surgical resection technique using frozen biopsy. Eighteen patients who underwent transsphenoidal surgery from 2004 to 2010 were included. High-resolution MRI and IPSS, multiple-staged resection, and tumor tissue identification in frozen sections (surgical and histological identification, SHI) were performed. All patients achieved surgical remission, as confirmed by 24 h urinary free cortisol excretion tests. Visible microlesions were identified on the initial MRI in 11 patients (61%). The SHI findings agreed with the MRI findings in 10 of the 11 patients (90.9%) and with IPSS lateralization in 6 of the 11 patients (54.5%). In the 7 patients whose lesions were not visible on the initial MRI, only 1 (14.3%) showed an agreement between IPSS and SHI. In 3 of the 7 patients, the microlesions were identified by additional MRI. The rate of concordance with SHI was 77.8% for the overall MRI and 38.9% for IPSS. High-resolution MRI is better than IPSS for localizing corticotroph adenomas. In patients with lesions not visible on the initial MRI, additional MRI should be performed using a different protocol. Although high-resolution MRI is better for localizing tumors, SHI remains an important approach for removing the tumors completely.

Is urinary free cortisol of value in the diagnosis of Cushing's syndrome?

PURPOSE OF REVIEW

Cushing's syndrome results from prolonged and inappropriately high exposure of tissues to glucocorticoids. Biochemical tests are always needed to confirm the clinical suspicion: these include measurement of excess total endogenous cortisol secretion assessed by 24-h urinary free cortisol (UFC), loss of the normal feedback of the hypothalamo-pituitary-adrenal axis assessed by suppressibility after dexamethasone testing, and disturbance of the normal circadian rhythm of cortisol secretion assessed by midnight serum or salivary cortisol. This review focuses on recent data emerging on the value of UFC as a screening test for Cushing's syndrome.

RECENT FINDINGS

Considerable evidence has emerged regarding the utility of UFC in the diagnosis of Cushing's syndrome because of its long-term use in clinical practice. Despite the fact that UFC assesses the active (free) component of cortisol, the methodological difficulties in 24-h urine collection and in assay precision have rendered this screening technique increasingly unpopular. Furthermore, the increased prevalence of mild, preclinical or cyclic Cushing's syndrome along with the fact that cortisol is not uniformly secreted during the day do not support its use as a screening test, although strikingly high levels can be useful.

SUMMARY

Since the sensitivity and specificity of UFC are less than ideal when compared with other diagnostic modalities, we suggest the use of other more novel tests as first-step diagnostic tests to screen for hypercortisolaemia.

Incidental and metastatic adrenal masses

In the last decades discoveries of adrenal masses incidentally during the course of diagnostic procedures for unrelated disorders (incidentalomas) have become progressively more frequent. The clinician in this position must answer two main questions: Is the mass benign or malignant?, and To what extent is the adrenal secretion altered? To come to a clinical decision, several diagnostic tools need to be engaged, starting with an accurate and correct radiological evaluation and a hormonal assessment of the adrenal function. When necessary, other diagnostic procedures such as functional imaging and fine-needle biopsy (FNB) can be considered in selected cases. Surgical removal is recommended for clinically relevant hypersecretory masses, as well as for masses suspected to be malignant. Most frequently, adrenal incidentalomas (AIs) are represented by benign cortical adenomas, a subset of which causes a mild hypercortisolism, known as subclinical Cushing's syndrome (SCS). The criteria to define this syndrome, as well as its treatment, are still debated and controversial. AIs that are not surgically removed should be re-examined in time to exclude a supervening increase in size or function. Follow-up criteria have not been established. Laparoscopic surgery is the recommended procedure to remove benign masses. The surgical procedure for adrenal malignancies is still debated.

The ectopic ACTH syndrome

Ectopic Cushing's syndrome usually relates to the ectopic ACTH syndrome (EAS) and represents ∼20% of ACTH-dependent and ∼10% of all types of Cushing's syndrome (CS). Nearly any neuroendocrine or non-endocrine tumours may be associated with EAS, but the more prevalent tumours are bronchial carcinoids, small cell lung carcinomas, pancreatic carcinoids, thymic carcinoids, medullary carcinomas of the thyroid, and phaeochromocytomas. Occult tumours are highly represented in all the series (12-38%) and constitute the more challenging cases of EAS, requiring long term follow-up. The lack of any completely reliable diagnostic test procedure and imaging to clearly reveal the source of EAS suggests that we should adopt a step-by-step multidisciplinary approach for their diagnosis and therapeutic management. Clinical features are often similar in ACTH-dependent CS, but the rapid onset and progress may suggest an ectopic source. A combination of biochemical tests and imaging studies seems the most appropriate approach for the prompt identification of EAS, even if there are several pitfalls to be avoided along the way. The most appropriate management for cure of EAS, when its source is identified, is surgical excision after controlling the hypercortisolaemia by inhibitors of cortisol secretion and other newer modalities alone or in combination; bilateral adrenalectomy remains an alternative option. Tumour histology, the presence of metastases and the effective control of hypercortisolaemia affect mortality and morbidity. If a source repeatedly fails to be found, the prognosis is often favourable but the identification of a malignant tumour should still be sought during life-long follow-up to avoid the calamity of misdiagnosis.

Effectiveness of cabergoline in monotherapy and combined with ketoconazole in the management of Cushing's disease

The expression of dopamine receptor subtypes has been reported in corticotroph adenomas, and this finding support the possibility for medical treatment of Cushing's disease (CD) with dopamine agonists when conventional treatment has failed. The aim of this study was to evaluate the effectiveness of cabergoline (at doses of up 3 mg/week), alone or combined with relatively low doses of ketoconazole (up to 400 mg/day), in 12 patients with CD unsuccessfully treated by transsphenoidal surgery. After 6 months of cabergoline therapy, normalization of 24 h urinary free cortisol (UFC) levels occurred in three patients (25%) at doses ranging from 2-3 mg/week, whereas reductions ranging from 15.0 to 48.4% were found in the remaining. The addition of ketonocazole to the nine patients without an adequate response to cabergoline was able to normalize UFC excretion in six patients (66.7%) at doses of 200 mg/day (three patients), 300 mg/day (two patients) and 400 mg/day (one patient). In the remaining patients UFC levels did not normalize but a significant reduction ranging from to 44.4 to 51.7% was achieved. In two of the six responsive patients to combination therapy, the weekly dose of cabergoline could be later reduced from 3 to 2 mg. Our findings demonstrated that cabergoline monotherapy was able to reverse hypercortisolism in 25% of patients with CD unsuccessfully treated by surgery. Moreover, the addition of relatively low doses of ketoconazole led to normalization of UFC in about two-thirds of patients not achieving a full response to cabergoline.

Usefulness of composite methionine-positron emission tomography/3.0-tesla magnetic resonance imaging to detect the localization and extent of early-stage Cushing adenoma

OBJECT

Fifty to eighty percent of Cushing disease is diagnosed by typical endocrine responses. Recently, the number of diagnoses of Cushing disease without typical Cushing syndrome has been increasing; therefore, improving ways to determine the localization of the adenoma and making an early diagnosis is important. This study was undertaken to determine the present diagnostic accuracy for Cushing microadenoma and to compare the differences in diagnostic accuracy between MR imaging and PET/MR imaging.

METHODS

During the past 3 years the authors analyzed the diagnostic accuracy in a series of 35 patients with Cushing adenoma that was verified by surgical pituitary exploration. All 35 cases of Cushing disease, including 20 cases of "overt" and 15 cases of "preclinical" Cushing disease, were studied. Superconductive MR images (1.5 or 3.0 T) and composite images from FDG-PET or methionine (MET)-PET and 3.0-T MR imaging were compared with the localization of adenomas verified by surgery.

RESULTS

The diagnostic accuracy of superconductive MR imaging for detecting the localization of Cushing microadenoma was only 40%. The causes of unsatisfactory results for superconductive MR imaging were false-negative results (10 cases), false-positive results (6 cases), and instances of double pituitary adenomas (3 cases). In contrast, the accuracy of microadenoma localization using MET-PET/3.0-T MR imaging was 100% and that of FDG-PET/3.0-T MR imaging was 73%. Moreover, the adenoma location was better delineated on MET-PET/MR images than on FDG-PET/MR images. There was no significant difference in maximum standard uptake value of adenomas evaluated by MET-PET between preclinical Cushing disease and overt Cushing disease.

CONCLUSIONS

Composite MET-PET/3.0-T MR imaging is useful for the improvement of the delineation of Cushing microadenoma and offers high-quality detectability for early-stage Cushing adenoma.

Assessment of serum-free cortisol levels in patients with adrenocortical carcinoma treated with mitotane: a pilot study

OBJECTIVE

Mitotane treatment in adrenocortical carcinoma (ACC) results in unreliable measurement of serum total cortisol (TC) levels because of an elevation in corticosteroid-binding globulin (CBG).

DESIGN

The use of a newly-developed serum-free cortisol (FC) assay was assessed to investigate the characteristics of a more valid measure of cortisol status.

PATIENTS

Sixty-two serum samples from patients with ACC treated with mitotane were studied. Different subgroups were studied according to mitotane levels (<14, 14-20 and >20 mg/dl), hydrocortisone replacement treatment, presence of Cushing's syndrome (CS) and adrenocorticotrophin (ACTH) levels.

MEASUREMENTS

Serum FC was measured using a newly-developed assay, TC, CBG and plasma ACTH using conventional laboratory kits; TC-to-CBG (Free cortisol index, FCI, nmol/mg) and TC-to-FC (TFR) ratios were calculated.

RESULTS

CBG levels were elevated and positively correlated to mitotane levels. FC was positively related to TC and FCI in nearly all subgroups studied. Plasma ACTH was negatively related to parameters of cortisol levels in the total samples studied. In the 'target' subgroup with normal ACTH levels and mitotane levels 14-20 mg/dl, no correlation of plasma ACTH with any parameter studied was seen, and FC suggested over-replacement with hydrocortisone treatment in the subgroup with CS.

CONCLUSIONS

FC measurement may offer additional information in the follow-up of patients on mitotane, especially when there is a history of CS which invalidates the use of acute changes in plasma ACTH as a parameter of hydrocortisone replacement. These preliminary data suggest that it may prove useful as a biochemical marker when TC or FCI are invalidated by mitotane treatment or plasma ACTH is suppressed by hypercortisolaemia. Larger studies are needed to substantiate the clinical utility of FC measurement in specific groups of patients.

Clinical features and management of ectopic ACTH syndrome at a single institute in Japan

Ectopic ACTH syndrome (EAS) is a diagnostic challenge because it is often indistinguishable from Cushing's disease. We describe our series of EAS patients referred to us during 1992-2009. Among 16 cases (9 females / 7 males), with mean age of 58.4 ± 19.0yr, the ectopic source was identified in ten (proven EAS), whereas unidentified in six (occult/unknown EAS). Their salient clinical manifestations included Cushingoid feature (88%), skin pigmentation (88%), profound hypokalemia (88%), hypertension (75%), diabetes/impaired glucose tolerance (75%), hyperlipidemia (69%), and severe infection (44%). Dynamic endocrine tests revealed markedly elevated plasma ACTH levels (211 ± 116pg/mL) and cortisol levels (60.9 ± 30.1µg/dL) which showed resistance to overnight high-dose (8mg) dexamethasone suppression test in 15 (94%) and unresponsiveness to CRH stimulation in 12 (75%). No ACTH gradient during inferior petrosal sampling was noted in 13 of 15 (87%). Imaging tests by CT/MRI identified the tumors in 8 of 16 (50%), in 4 of 11 (36%) and 4 of 6 (66.7%) octreotide-responders by somatostatin receptor scintigraphy, but in only one of 9 (11.1%) by FDG-PET scan. Six cases deceased, including small cell carcinoma (2) and adenocarcinoma (1) of lung, neuroendocrine carcinoma of pancreas (1) and stomach (1), and olfactory neuroblastoma (1), whereas 4 cases survived after removal of the tumors, including bronchial carcinoid tumor (3) and thymic hyperplasia (1). Six occult/unknown EAS patients survived for 67.5 months after medical treatment with metyrapone to control hypercortisolism. Thus, various endocrine tests combined with imaging studies are required to correctly localize the tumors. Control of hypercortisolemia by metyrapone, even if tumor is unrecognized, is critical for better prognosis, and the long-term follow-up by repeated endocrine and imaging tests is mandatory.

Stress and obesity: the role of the hypothalamic-pituitary-adrenal axis in metabolic disease

PURPOSE OF REVIEW

Chronic stress, combined with positive energy balance, may be a contributor to the increased risk for obesity, especially upper body obesity, and other metabolic diseases. This association may be mediated by alterations in the hypothalamic-pituitary-adrenal (HPA) axis. In this review, we summarize the major research that has been conducted on the role of the HPA axis in obesity and metabolic disease.

RECENT FINDINGS

Dysregulation in the HPA axis has been associated with upper body obesity, but data are inconsistent, possibly due to methodological differences across studies. In addition to systemic effects, changes in local cortisol metabolism in adipose tissue may also influence the risk for obesity. HPA axis dysregulation may be the causal link between conditions such as maternal malnutrition and sleep deprivation with metabolic disease.

SUMMARY

The present review provides evidence for the relationship between chronic stress, alterations in HPA activity, and obesity. Understanding these associations and its interactions with other factors will be important in developing effective treatments for obesity and related metabolic diseases.

[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.

The role of non-invasive dynamic tests in the diagnosis of Cushing's syndrome

OBJECTIVE

To evaluate the role of non-invasive dynamic tests in the diagnosis and differential diagnosis of Cushing's syndrome (CS).

METHODS

We studied laboratory features of 74 patients with endogenous CS, subdivided as follows: 46 (62.1%) with Cushing's disease (CD), 21 (28.3%) with an adrenal tumor, and 7 (9.5%) with ectopic ACTH syndrome (EAS).

RESULTS

In 100% of cases of CS we found serum cortisol levels greater than 1.8 microg/dl after low-dose dexamethasone suppression tests (LDDST), as well as elevation of midnight serum or salivary 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 invariably increased in EAS. After the 8-mg overnight dexamethasone suppression test (HDDST), serum cortisol suppression >50% was observed in 79.5% of cases of CD and in 28.6% of subjects with EAS, whereas cortisol suppression >80% was only found in CD. After stimulation with CRH or desmopressin an ACTH rise > or =35% occurred in 86.5% of individuals with CD and 14.3% of those with EAS, whereas an ACTH rise > or =50 achieved 100% specificity. Moreover, the combination of serum cortisol suppression >50% after HDDST and an ACTH increase > or =35% after the administration of CRH or desmopressin only occurred in CD.

CONCLUSION

Our findings demonstrate that LDDST had 100% sensitivity for the diagnosis of CS and that HDDST and stimulation tests with CRH or desmopressin may be very useful for confirmation of CS etiology when analyzed together or when more stringent cut-offs are used.