The Optimal Cut-off of BIPSS in Differential Diagnosis of ACTH-dependent Cushing's Syndrome: Is Stimulation Necessary?

Utility of Simple and Non-Invasive Strategies Alternative to Inferior Petrosal Sinus Sampling and Peripheral CRH Stimulation in Differential Diagnosis of ACTH-Dependent Cushing Syndrome

We aimed to evaluate the utility of simple, cost-effective, and non-invasive strategies alternative to BIPSS and peripheral CRH stimulation in differential diagnosis of ACTH-dependent CS. First, we performed ROC analysis to evaluate the performance of various tests for differential diagnosis of ACTH-dependent CS in our cohort (CD, n=76 and EAS, n=23) and derived their optimal cut-offs. Subsequently, combining various demographic (gender), clinical (hypokalemia), biochemical (plasma ACTH, HDDST, peripheral CRH stimulation) and imaging (MRI pituitary) parameters, we derived non-invasive models with 100% PPV for CD. Patients with pituitary macroadenoma (n=14) were excluded from the analysis involving non-invasive models. Relative percent ACTH (AUC: 0.933) and cortisol (AUC: 0.975) increase on peripheral CRH stimulation demonstrated excellent accuracy in discriminating CD from EAS. Best cut-offs for CD were plasma ACTH<97.3 pg/ml, HDDST≥57% cortisol suppression, CRH stimulation≥77% ACTH increase and≥11% cortisol increase. We derived six models that provided 100% PPV for CD and precluded the need for BIPPS in 35/85 (41.2%) patients with ACTH-dependent CS and no macroadenoma (in whom BIPSS would have otherwise been recommended). The first three models included basic parameters and avoided both peripheral CRH stimulation and BIPSS in 19 (22.4%) patients, while the next three models included peripheral CRH stimulation and avoided BIPSS in another 16 (18.8%) patients. Using simple and non-invasive alternative strategies, BIPSS can be avoided in 41% and peripheral CRH stimulation in 22% of patients with ACTH-dependent CS and no macroadenoma; such patients can be directly referred for a pituitary surgery.

Subtyping of Cushing's Syndrome: A Step Ahead

Cushing's Syndrome (CS) is a rare disease due to chronic endogenous cortisol secretion. In recent years, new developments have broadened the spectrum of differential diagnosis, traditionally categorized as adrenocorticotropic hormone (ACTH)-dependent and ACTH-independent forms. Moreover, increased awareness of the detrimental effects of cortisol on cardiometabolic health and the risk of cardiovascular events lead to increased diagnosis of mild forms, especially in the context of adrenal incidentalomas.This review provides an up-to-date narrative of the most recent literature regarding the challenges of CS diagnosis. After the description of the diagnostic tools available, the functional non-neoplastic hypercortisolism (formerly known as pseudo-Cushing state) is characterized, followed by the subtyping of the different conditions of hypercortisolism, including the differential diagnosis of ACTH-dependent forms and the management of adrenal hypercortisolism, with peculiar attention to the new genetic classification of adrenal CS, mild autonomous cortisol secretion, and bilateral adrenal adenomas.

Bilateral Inferior Petrosal Sinus Sampling Without Lateralization Is Less Accurate for the Diagnosis of Cushing Disease

Context

During bilateral inferior petrosal sinus sampling (BIPSS), the side-to-side adrenocorticotropic hormone (ACTH) ratio, referred to as sampling lateralization, was used to predict pituitary adenoma localization.

Objective

To investigate the potential different diagnostic accuracy of BIPSS for differentiating Cushing disease (CD) and ectopic ACTH secretory syndrome (EAS) patients with low lateralization (inferior petrosal sinus [IPS]:IPS ≤ 1.4) and high lateralization (IPS:IPS > 1.4).

Methods

This single-center retrospective study (2011-2021) included (all patients had BIPSS results and confirmed pathologic diagnoses) 220 consecutive CD patients (validation set), 30 EAS patients, and 40 of the CD patients who had digital subtraction angiography (DSA) videos (discovery set).

Results

In the discovery set, the low-lateralization CD group (n = 11) had a higher median plasma ACTH concentration (62.2, IQR 44.7-181.0 ng/L) than the high-lateralization CD group (n = 29) (33.0, IQR 18.5-59.5, P = .013). Lower IPS to peripheral ratios were observed in the low-lateralization group during BIPSS, both before and after stimulation (P = .013 and P = .028). The sensitivity of BIPSS before stimulation in differentiating CD from EAS was lower in the low-lateralization group than the high-lateralization group (54.6% vs 93.1%, P = .003), as validated in the validation set. DSA videos revealed higher vascular area difference visible in the 2 sides of the pituitary in low lateralization (median 1.2 × 105 pixels, IQR 0.5-1.8) than the high-lateralization group (0.4 × 105 pixels, IQR 0.1-0.7, P = .008). The vascular area ratio of the 2 sides was also significantly higher in low (1.55, IQR 1.31-2.20) than high lateralization (1.19, IQR 1.07-1.35, P = .010).

Conclusion

Our study suggested that low lateralization in CD patients may reduce the diagnostic sensitivity of BIPSS, which might be potentially associated with peripituitary vascular anatomy.

False Negative Inferior Petrosal Sinus Sampling in Young-Onset Cushing Disease: What Happens Next

INTRODUCTION

False negative results during inferior petrosal sinus sampling (IPSS) may complicate the diagnostic evaluation of patients with ACTH-dependent Cushing syndrome (CS). The management of these patients can be confusing for clinicians and lead to delayed management.

METHODS

We studied patients with young-onset (<21yo) CD who underwent IPSS during their diagnostic evaluation. For all patients, diagnosis of CD was eventually confirmed based on histologic evaluation of a resected pituitary tumor or remission after transsphenoidal surgery (TSS).

RESULTS

We recorded a rare incidence of false negative IPSS results in 5 out of the 142 IPSS procedures (3.5%), performed in 4 unique patients. Patients with negative IPSS did not differ in demographic (age and sex) or biochemical (diurnal ACTH/cortisol or 24hour urinary free cortisol) data from the remaining. Additional workup was performed in three of the four patients including evaluation for ectopic sources of CS and repeat IPSS. Two of these patients also received medical treatment for suppression of cortisol production. One patient decided to proceed with pituitary exploration without additional evaluation. All patients finally underwent surgery and achieved remission.

DISCUSSION/CONCLUSION

In patients with CD, IPSS may rarely lead to false negative results. Management of these patients usually includes screening for ectopic sources of ACTH/CRH secretion, repeating IPSS if ectopic workup is negative, and considering medical management until final diagnosis of the source of hypercortisolism is made.

Bilateral inferior petrosal sinus sampling: validity, diagnostic accuracy in lateralization of pituitary microadenoma, and treatment in eleven patients with Cushing's syndrome - a single-center retrospective cohort study

BACKGROUND

This single-center retrospective cohort study aimed to describe the findings and validity of Bilateral inferior petrosal sinus sampling (BIPSS) in the differential diagnosis of patients with ACTH-dependent Cushing's syndrome (CS).

METHODS

Eleven patients underwent BIPSS due to equivocal biochemical tests and imaging results. Blood samples were taken from the right inferior petrosal sinus (IPS), left IPS, and a peripheral vein before and after stimulation with desmopressin (DDAVP). ACTH and prolactin levels were measured. The diagnosis was based on the ACTH ratio between the IPS and the peripheral vein. Also, lateralization of pituitary adenoma in patients with Cushing's disease (CD) was predicted. No significant complications were observed with BIPSS.

RESULTS

Based on the pathology report, eight patients had CD, and three had ectopic ACTH syndrome (EAS). Unstimulated BIPSS resulted in a sensitivity of 87.5%, specificity of 100%, PPV of 100%, NPV of 75%, and accuracy of 91%. Stimulated BIPSS resulted in a sensitivity of 100%, specificity of 100%, PPV of 100%, NPV of 100%, and accuracy of 100%. However, pituitary magnetic resonance imaging (MRI) had a lower diagnostic accuracy (sensitivity:62.5%, specificity:33%, PPV:71%, NPV:25%, accuracy:54%). BIPSS accurately demonstrated pituitary adenoma lateralization in 75% of patients with CD.

CONCLUSIONS

This study suggests that BIPSS may be a reliable and low-complication technique in evaluating patients with ACTH-dependent CS who had inconclusive imaging and biochemical test results. The diagnostic accuracy is improved by DDAVP stimulation. Pituitary adenoma lateralization can be predicted with the aid of BIPSS.

Osteoporosis as the First Sign of Cushing's Disease in a Thin 16-Year-Old Boy-A Case Report

Cushing's disease (CD) is an extremely rare diagnosis in children. In this report, we present the case of an almost 16-year-old, short and thin boy with CD, the first symptoms of which were spinal pain and vertebral fractures as a result of osteoporosis. In light of his growth retardation and short stature, the boy underwent diagnostics, which excluded growth hormone (GH) deficiency, hypothyroidism and celiac disease. Finally, based on cortisol profile results, dexamethasone suppression tests and bilateral sampling during catheterization of the inferior petrosal sinuses, CD was diagnosed.

Enhancing Cushing's disease diagnosis: exploring the impact of desmopressin on ACTH gradient during BIPSS

Introduction

The differential diagnosis between Cushing's disease (CD) and ectopic ACTH syndrome (EAS) is complex, and bilateral inferior petrosal sinus sampling (BIPSS) is considered the gold-standard test. However, BIPSS with corticotropin-releasing hormone (CRH) stimulation is rarely available.

Objective

This retrospective cohort study aimed to assess the accuracy of the inferior petrosal sinus to peripheral ACTH gradient (IPS:P) before and after desmopressin stimulation for the differential diagnosis of ACTH-dependent Cushing's syndrome (CS), applying different cutoff values.

Methods

A total of 50 patients (48 with CD and 2 with EAS) who underwent BIPSS were included in this study. The sensitivity and specificity of IPS:P in BIPSS before and after desmopressin stimulation were evaluated. Various cutoff values for IPS:P were examined to determine their diagnostic accuracy.

Results

Using the traditional IPS:P cutoff, the sensitivity was 85.1% before stimulation, 89.6% after stimulation, and a combined sensitivity of 91.7%. Applying cutoff values of IPS:P >1.4 before and >2.8 after stimulation, the sensitivity was 87.2% and 89.6%, respectively, with a combined sensitivity of 91.7%. Receiver operating characteristic (ROC) curve analysis determined optimal cutoff values of 1.2 before stimulation and 1.57 after stimulation, resulting in a sensitivity of 93.6% and 93.8%, respectively, with a combined sensitivity of 97.9%. Specificity remained at 100% throughout all analyses. Among the 43 patients who responded positively to stimulation, 42 (97.7%) did so within the first three minutes, and all 43 (100%) did so within the first five minutes. None of the assessed clinical variables predicted the ACTH response to stimulation in BIPSS with statistical significance.

Discussion

ACTH stimulation with desmopressin during BIPSS improves the accuracy of IPS:P, making it a valuable tool for investigating ACTH-dependent Cushing's syndrome. Considering the low risk of complications, we recommend the use of desmopressin stimulation during BIPSS for the differential diagnosis of ACTH-dependent CS.

Misdiagnosed psychiatric manifestations in a rare disease: a case report of secondary anxiety syndrome in Cushing's disease

Diagnosing and treating secondary psychiatric symptoms with accuracy can be challenging in clinical settings. In this case study, we report on a female patient with Cushing's disease who was misdiagnosed with anxiety disorder during her first psychiatric visit. Following initial ineffective psychiatric intervention, unexplained hypokalemia, and hypothyroidism, the patient visited the endocrinology clinic and was diagnosed with Cushing's disease. During the medical and surgical procedures that followed, high doses of psychotropic medication were continued to treat persisting anxiety. After discharge, the patient developed autonomic dysfunction and impaired consciousness. Upon readmission, serotonin syndrome due to inappropriate psychiatric medication was diagnosed. The management of secondary psychiatric syndromes must be adapted to changes in the patient's primary condition, which necessitates interdisciplinary collaboration in general hospital settings.

Dynamic testing for differential diagnosis of ACTH-dependent Cushing Syndrome: a systematic review and meta-analysis

OBJECTIVE

Diagnostic accuracy of testing currently used for the differential diagnosis of Cushing's disease (CD) vs ectopic -ACTH secretion (EAS) is difficult to interpret. The present study aimed to identify and evaluate the diagnostic accuracy of corticotropin-releasing hormone (CRH) test, desmopressin test, and high-dose dexamethasone suppression test (HDDST) when used to establish a CD or EAS diagnosis.

DESIGN

This study is a systematic review of the literature and meta-analysis.

METHODS

MEDLINE, OVID, and Web of Science databases were searched for articles published between the years 1990-2021. Articles included described at least one test(s) (CRH, desmopressin, or HDDST) and the diagnostic reference standard(s) (histopathology, petrosal sinus sampling, surgical remission, imaging, and long-term follow-up) used to establish a CD or EAS diagnosis.

RESULTS

Sixty-two studies were included: 43 reported the use of HDDST, 32 CRH test, and 21 desmopressin test. CRH test was found to have the highest sensitivity in detecting CD (ACTH 86.9%, 95% confidence interval [CI] 82.1-90.6, cortisol 86.2%, 95%CI 78.3-91.5) and the highest specificity in detecting EAS (ACTH 93.9%, 95%CI 87-98.3, cortisol 89.4%, 95%CI 82.8-93.7). This resulted in a high diagnostic odds ratio (58, 95%CI 43.25-77.47), large area under the curve, and a receiver-operating characteristic (ROC) of 0.934. The diagnostic accuracy of HDDST and desmopressin test(s) was lower than that of the CRH test.

CONCLUSION

The meta-analysis indicates that a patient with a positive ACTH response after a CRH test is highly likely to have CD. Further studies analysing role of dynamic testing in addition to imaging are needed.

Is Desmopressin Useful in the Evaluation of Cushing Syndrome?

The desmopressin test was first described 30 years ago. Based on the differential secretagogue properties of desmopressin on adrenocorticotropin (ACTH) release between normal and corticotroph tumor cells, this test was intended to facilitate the diagnosis of Cushing syndrome (CS). The distinct expression of the various arginine vasopressin receptors between normal pituitary, corticotroph tumors, or neuroendocrine tumors cells secreting ACTH ectopically suggested that this test could facilitate the etiological diagnosis of ACTH-dependent CS. In this review, we analyze the merits and pitfalls of desmopressin use in the diagnostic procedures of CS. Desmopressin response is not able to completely differentiate the various etiologies of CS; its wider availability has allowed its use for inferior petrosal sinus sampling confirmation of a pituitary source of ACTH excess. In addition, desmopressin can be useful to demonstrate adequate corticotroph tumor resection when its stimulatory effect is lost following pituitary surgery of patients with Cushing disease. Desmopressin response can also be a marker of the risk of longer-term postoperative recurrence. However, this review also highlights the lack of consensual criteria of normal or abnormal response to desmopressin in its various uses and requirement for further research on its usefulness.

Outcome of CRH stimulation test and overnight 8 mg dexamethasone suppression test in 469 patients with ACTH-dependent Cushing's syndrome

OBJECTIVE

To evaluate diagnostic accuracy of the corticotropin-releasing hormone (CRH) stimulation test and the overnight 8 mg dexamethasone suppression test (DST) for the differentiation of Cushing's disease (CD) and ectopic Cushing's syndrome (ECS).

METHODS

Retrospective study in 6 European centers. Inclusion criteria: patients with a) overt adrenocorticotropin (ACTH)-dependent Cushing's syndrome at the time of dynamic testing, b) histopathological confirmed tumors and/or c) postoperative biochemical remission and/or adrenal insufficiency. Optimal cut-offs were calculated via receiver operating characteristic (ROC) analysis using CD as reference.

RESULTS

469 patients were analyzed [78% females; median age 43 years (IQR 19)]. CRH test and overnight 8 mg DST were performed in 420 [CD, n=394 (94%); ECS, n=26 (6%)] and 237 patients [228 CD (96%), 9 ECS (4%)]. Both tests were performed in 205 patients (44%). The post-CRH %-increase at 30 minutes of both ACTH (cut-off ≥31%, sensitivity 83%, specificity 85%, AUC 0.81) and cortisol (cut-off ≥12%, sensitivity 82%, specificity 89%, AUC 0.86) discriminated best between CD and ECS. A test duration of >60 minutes did not improve diagnostic performance of the CRH test. The optimal cortisol cut-off for the %-suppression during the 8 mg DST was ≥55% (sensitivity 80%, specificity 78%, AUC 0.75).

CONCLUSION

The CRH test has equivalent sensitivity but higher specificity than the 8 mg DST and is therefore the test of first choice. The diagnostic outcome of ACTH and cortisol is well comparable, however, sampling beyond 60 minutes post-CRH does not provide diagnostic benefits.

Second-Line Tests in the Diagnosis of Adrenocorticotropic Hormone-Dependent Hypercortisolism

Cushing’s syndrome (CS) is a rare disease caused by chronic and excessive cortisol secretion. When adrenocorticotropin hormone (ACTH) is measurable, autonomous adrenal cortisol secretion could be reasonably ruled out in a differential diagnosis of CS. ACTH-dependent CS accounts for 80%–85% of cases and involves cortisol production stimulated by uncontrolled pituitary or ectopic ACTH secretion. Pituitary adenoma is not detected in up to one-third of cases with pituitary ACTH secretion, whereas cases of CS due to ectopic ACTH secretion may be associated with either malignant neoplasia (such as small cell lung carcinoma) or less aggressive neuroendocrine tumors, exhibiting only the typical symptoms and signs of CS. Since the differential diagnosis of ACTH-dependent CS may be a challenge, many strategies have been proposed. Since none of the available tests show 100% diagnostic accuracy, a step-by-step approach combining several diagnostic tools and a multidisciplinary evaluation in a referral center is suggested. In this review, we present a clinical case to demonstrate the diagnostic work-up of ACTH-dependent CS. We describe the most commonly used dynamic tests, as well as the applications of conventional or nuclear imaging and invasive procedures.

Inferior petrosal sinus sampling in Cushing's syndrome: usefulness and pitfalls

In patients with ACTH-dependent Cushing's syndrome (CS), the differentiation between Cushing's disease (CD) and ectopic ACTH secretion (EAS) can often be challenging. The traditionally used biochemical tests have limited diagnostic accuracy and imaging modalities may fail to detect the culprit lesion. Inferior petrosal sinus sampling (IPSS) was introduced more than 3 decades ago as a test with optimal diagnostic accuracy and has since become the gold standard in the differential diagnosis between CD and EAS. However, several, albeit rare, pitfalls may limit its diagnostic accuracy and awareness is needed to avoid incorrect interventions. Moreover, it is an invasive and demanding procedure, available in a limited number of centers worldwide. This review aims to critically present the usefulness and pitfalls of IPSS and define strategies for its optimal place in the contemporary management of CS.

Development and validation of a novel index for the differential diagnosis of corticotropin-dependent Cushing syndrome

PURPOSE

To develop an index for the differential diagnosis of corticotropin-dependent Cushing syndrome (CS).

METHODS

The development cohort included 112 consecutive patients with clinicopathologically confirmed corticotropin-dependent CS at the Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, from December 2004 to May 2020, and data of 126 patients from studies published from 2016 to August 2020, identified through search in PubMed, Embase and the Cochrane Library, was extracted for external validation. The index was calculated as the product of plasma adrenocorticotropic hormone (ACTH, pmol/L) and urinary free cortisol (UFC, nmol/24 h) divided by 10,000. The discriminative ability was tested using receiver operating characteristics (ROC) curve analysis.

RESULTS

In development cohort, area under curve of ROC analysis of the ACTH-UFC index in identifying Cushing disease (CD) was 0.977. The diagnostic accuracy of ACTH-UFC index ≤ 11 was comparable to that of 48 h 8 mg/d high-dose dexamethasone test (HDDST) in identifying CD, with sensitivity, specificity, positive and negative likelihood ratios of 96.6%, 87.5%, 7.73, and 0.04, respectively. The sensitivity of ACTH-UFC index ≤ 11 in parallel combination with pituitary magnetic resonance imaging (MRI) was 100% for identifying CD. The performance of the ACTH-UFC index in parallel or serial combination with pituitary MRI was similar in the validation cohort.

CONCLUSIONS

ACTH-UFC index provides a rapid, convenient and non-invasive adjunctive approach for the differential diagnosis of corticotropin-dependent CS, with no risk of aggravating metabolic disturbances. Investigations for ectopic causes of corticotropin-dependent CS should be performed with ACTH-UFC index > 11 and negative contrasted pituitary MRI.

Inferior petrosal sinus sampling and stimulation with CRH: 15 years of experience in a tertiary hospital

BACKGROUND

Inferior petrosal sinus sampling (IPSS) is indicated in the diagnosis of adrenocorticotropic hormone (ACTH)-dependent Cushing's syndrome (CS), especially when the results of the initial diagnostic tests are discordant.

OBJECTIVE

To describe the patients who underwent this invasive functional test in a tertiary hospital.

METHODS

This was an observational study of a retrospective cohort of patients with ACTH-dependent CS and IPSS between 2004 and 2019. We determined their epidemiological, hormonal, radiological and functional characteristics, and evaluated their diagnostic capacity and optimal cut-off points to differentiate between Cushing's disease (CD) and ectopic Cushing's syndrome (ECS).

RESULTS

23 patients were evaluated, of which 65.2% were women with the average age of 42 (36-62) years. ACTH secretion of pituitary origin was evident in 82.6% of the patients and of ectopic origin in 17.4%. Plasma cortisol, urinary free cortisol, and ACTH levels were higher in patients with ECS. Regarding IPSS, the baseline central/peripheral ACTH gradient detected 89.5% of patients with CD and after stimulation with CRH, 100%. The optimal cut-off points in the diagnosis of CD were 2.06 at baseline and 2.49 after CRH stimulation.

CONCLUSION

IPSS with CRH stimulation is a test with a high diagnostic accuracy for correctly classifying patients with CD and ECS. The cut-off points of the gradients may be different from the classic ones. Therefore, we recommend that each center perform its own evaluation.

Diagnosis, Manifestations, Laboratory Investigations, and Prognosis in Pediatric and Adult Cushing's Disease in a Large Center in China

PURPOSE

Cushing's disease (CD) is a rare disease that contributes to 70-80% hypercortisolemia, which presents similarities and differences between pediatric and adult patients, and even between male and female patients. However, the comparative study of CD between different age groups and different genders is still insufficient. The aim of the study is to make a systematic comparison to reveal the gender differences in children and adult patients of CD, helping clinicians to provide optimal treatment for different groups of patients.

METHODS

We conducted a retrospective research consisting of 30 pediatric and 392 adult CD patients in a single center in Peking Union Medical College Hospital. All 422 patients showed symptoms related to hypercortisolism and received adenoma excision surgery in the department of neurosurgery between 2014 and 2020.

RESULTS

For the accuracy of diagnosis, the sensitivity of BIPSS at baseline in pediatric patients was lower than in adults (75 vs. 91%, P = 0.054) but increased greatly after desmopressin stimulation (94 vs. 95%). However, the accuracy of lateralization for BIPSS was not preferred for prediction. As for clinical manifestations, growth retardation, weight gain, hirsutism, and acne were more prevalent for children, while for adults, hypertension, osteopenia, glucometabolic disorder, easy bruising, hair loss, and weight loss were more frequently seen. As previously reported, we observed a significant difference between the male prevalence of pediatric and adult patients (50 vs. 17%, P < 0.001), which was possibly caused by the more severe and earlier onset of a series of symptoms. Gender-related comparison showed greater morbidity of nephrolithiasis, hypokalemia, hypertension, easy bruising, osteopenia, and striae for male patients, while irregular menses, hirsutism, and hair loss were more common for female patients. Further analysis showed that the secretory activity of the PA axis was higher for males, presenting as the more remarkable alteration of laboratory parameters and contributing to the more severe clinical manifestations. For patients treated with transsphenoidal pituitary surgery (TSS), the immediate prognosis could be predicted by operation history, invasiveness, Ki-67, and information provided by MRI, including tumor size and Knosp grading. However, we still lack methods to predict long-term prognosis.

CONCLUSIONS

Our study is the first detailed and systematic comparison between pediatric and adult CD patients. Further exploration of the impact of CD on different genders reveals a more severe and probably an earlier-onset pattern of CD for male patients.

An Optimized Pathway for the Differential Diagnosis of ACTH-Dependent Cushing's Syndrome Based on Low-Dose Dexamethasone Suppression Test

CONTEXT

Traditionally, low-dose dexamethasone suppression test (LDDST) was used to confirm the diagnosis of Cushing's syndrome (CS), and high-dose dexamethasone suppression test (HDDST) was used to differentiate Cushing's disease (CD) and ectopic adrenocorticotropin (ACTH) syndrome (EAS), but some studies suggested that HDDST might be replaced by LDDST. For the differential diagnosis of CS, dexamethasone suppression test was usually combined with other tests such as bilateral petrosal sinus sampling (BIPSS) and pituitary magnetic resonance imaging, but the optimal pathway to incorporate these tests is still controversial.

OBJECTIVES

To develop an optimized pathway for the differential diagnosis of CD and EAS based on LDDST.

DESIGN AND SETTING

Single-center retrospective study (2011-2019).

PATIENTS

Two hundred sixty-nine CD and 29 EAS patients with pathological diagnosis who underwent consecutive low- and high-dose DST.

RESULTS

For the differential diagnosis of CD and EAS, the area under curve (AUC) of LDDST using urine free cortisol (0.881) was higher than that using serum cortisol (0.685) (p < 0.001) in head-to-head comparison among a subgroup of 108 CD and 10 EAS. The AUC of LDDST (0.883) was higher than that of HDDST (0.834) among all the included patients. With the cutoff of <26%, the sensitivity and specificity of LDDST were 39.4% and 100%. We designed a new pathway in which BIPSS was only reserved for those patients with unsuppressed LDDST and adenoma <6mm, yielding an overall sensitivity of 97.7% and specificity of 86.7%.

CONCLUSION

LDDST had similar value to HDDST in differentiating CD and EAS using the specific cutoff point. The pathway that combined LDDST and BIPSS could differentiate CD and EAS accurately.

Steroid profiling in the diagnosis of mild and overt Cushing's syndrome

In this review, we provide a comprehensive overview of the utility of steroid profiling for diagnosis of management of overt Cushing syndrome and mild autonomous cortisol secretion. A diagnosis of Cushing syndrome is made through a multistep process that includes confirmation of endogenous hypercortisolism, followed by determination of its cause. Steroid metabolomic testing applied to serum or urine steroids and their metabolites can provide additional and novel insights into alterations of steroid biosynthesis and metabolism and its causes. In particular, increased availability and advances in mass spectrometry-based steroid analysis, coupled with machine learning-based algorithms, have facilitated the development of tailored diagnostic and subtyping approaches for autonomous cortisol secretion and might be useful for detecting low grade autonomous glucocorticoid secretion and in predicting and monitoring of disease severity and associated comorbidities.