Hypercoagulability in Cushing's syndrome: incidence, pathogenesis and need for thromboprophylaxis protocols.

Cushing's syndrome (CS) is associated with a hypercoagulable state resulting in an increased risk on venous thromboembolism (VTE). In patients with untreated active CS VTE incidence is up to 18-fold higher compared to the general population, whereas after pituitary and adrenal surgery a postoperative VTE risk between 2.6 and 5.6% has been reported. Interestingly, after surgery the VTE risk is not only increased in the first week but also during several months postoperatively. The hypercoagulable state in CS is thought to be caused, at least in part, by an imbalance between activity of pro- and anticoagulant pathways. However, changes in activated partial thromboplastin time and plasma concentrations of pro-and anticoagulant factors are not observed in every CS patient. Only retrospective studies have shown that thromboprophylaxis lowers VTE risk in CS. Future prospective studies should asses the optimal timing, duration and type of thromboprophylaxis in CS to improve VTE-related morbidity and mortality.

The NIMH Intramural Longitudinal Study of the Endocrine and Neurobiological Events Accompanying Puberty: Protocol and rationale for methods and measures.

Delineating the relationship between human neurodevelopment and the maturation of the hypothalamic-pituitary-gonadal (HPG) axis during puberty is critical for investigating the increase in vulnerability to neuropsychiatric disorders that is well documented during this period. Preclinical research demonstrates a clear association between gonadal production of sex steroids and neurodevelopment; however, identifying similar associations in humans has been complicated by confounding variables (such as age) and the coactivation of two additional endocrine systems (the adrenal androgenic system and the somatotropic growth axis) and requires further elucidation. In this paper, we present the design of, and preliminary observations from, the ongoing NIMH Intramural Longitudinal Study of the Endocrine and Neurobiological Events Accompanying Puberty. The aim of this study is to directly examine how the increase in sex steroid hormone production following activation of the HPG-axis (i.e., gonadarche) impacts neurodevelopment, and, additionally, to determine how gonadal development and maturation is associated with longitudinal changes in brain structure and function in boys and girls. To disentangle the effects of sex steroids from those of age and other endocrine events on brain development, our study design includes 1) selection criteria that establish a well-characterized baseline cohort of healthy 8-year-old children prior to the onset of puberty (e.g., prior to puberty-related sex steroid hormone production); 2) temporally dense longitudinal, repeated-measures sampling of typically developing children at 8-10 month intervals over a 10-year period between the ages of eight and 18; 3) contemporaneous collection of endocrine and other measures of gonadal, adrenal, and growth axis function at each timepoint; and 4) collection of multimodal neuroimaging measures at these same timepoints, including brain structure (gray and white matter volume, cortical thickness and area, white matter integrity, myelination) and function (reward processing, emotional processing, inhibition/impulsivity, working memory, resting-state network connectivity, regional cerebral blood flow). This report of our ongoing longitudinal study 1) provides a comprehensive review of the endocrine events of puberty; 2) details our overall study design; 3) presents our selection criteria for study entry (e.g., well-characterized prepubertal baseline) along with the endocrinological considerations and guiding principles that underlie these criteria; 4) describes our longitudinal outcome measures and how they specifically relate to investigating the effects of gonadal development on brain development; and 5) documents patterns of fMRI activation and resting-state networks from an early, representative subsample of our cohort of prepubertal 8-year-old children.

Endocrine-Related Adverse Events Related to Immune Checkpoint Inhibitors: Proposed Algorithms for Management.

Immune checkpoint inhibitors have proven to be effective for various advanced neoplasia. Immune-related adverse events (irAEs) as a result of increased T cell activation are unique and potentially life-threating toxicities associated with the use of immune checkpoint inhibitors. Multiple endocrine irAEs, including primary hyperthyroidism and hypothyroidism, thyroiditis, primary adrenal insufficiency, type 1 diabetes mellitus, and hypophysitis, have been reported with the use of various immune checkpoint inhibitors. In some cases, these irAEs can lead to discontinuation of treatment. Here we propose for the general oncologist algorithms for managing endocrine irAEs to aid in the clinical care of patients receiving immunotherapy. KEY POINTS: There is a relative high risk of endocrine immune-related adverse events (irAEs) during therapy with checkpoint inhibitors, particularly when combination therapy is implemented. Patients treated with anti-CTLA-4 antibodies have an increased risk of hypophysitis, whereas patients treated with anti-PD-1/PD-L1 antibodies have a higher risk of primary thyroid dysfunction. Rarely, patients develop T1DM and central diabetes insipidus, and hypoparathyroidism is a rare occurrence. A growing clinical understanding of endocrine irAEs has led to effective treatment strategies with hormone replacement.

Remission of hypertension after surgical cure of Cushing's syndrome.

CONTEXT: Hypertension associated with Cushing's syndrome (CS) increases cardiovascular risk. The time-course of improvement after cure is unclear. OBJECTIVE: To describe the time-course and predictors of blood pressure (BP) normalization during one year after surgical cure of CS. DESIGN: Retrospective chart review of 75 hypertensive adults cured of CS (72 with ACTH-dependent CS; 3 with adrenal adenoma). Hypertension was defined as current use of antihypertensives, a systolic BP >130 mm Hg, or diastolic BP >80 mm Hg. MAIN OUTCOME MEASURE(S): Remission of hypertension: BP ≤130/80 mm Hg and no antihypertensive medications. Improvement in hypertension: BP >130/80 mm Hg and decreased number or dose of medications, or blood pressure ≤130/80 with continued use of medications at constant dose. RESULTS: At postoperative discharge, 17 (23%, P < .001), 51 (68%, P < .001) and 7 (9%) patients had remission, improvement in hypertension or no change. Twenty-nine had no follow-up. Others achieved remission at 3 (n = 5), 6 (n = 6), or 12-months (n = 5). At the last evaluation, 33/75 (44%) had remission, 36/75 (48%) had improved hypertension and 6 were unchanged. Patients with improvement discontinued a median of one medication (P < .001). At 12-months, 27/42 (64%) patients had normal BP (P < .002). Longer estimated duration of CS (P = .0106), younger age (P = .0022), and lower baseline body mass index (P = .0413) predicted hypertension remission. CONCLUSIONS: About 80% of CS patients experienced BP normalization or improvement within 10 days of cure, but about half failed to normalize BP by one year. BP should be monitored after cure, and antihypertensive medications adjusted to avoid unwanted cardiovascular effects.

Transdermal estradiol for postpartum depression: results from a pilot randomized, double-blind, placebo-controlled study.

Postpartum depression (PPD) is a common complication following delivery, though evidence-based treatment options are limited. This study explores the feasibility and efficacy of outpatient PPD treatment with transdermal estradiol (TE). In a pilot, double-blind, placebo-controlled trial, women with PPD were randomized to receive transdermal 17ß-estradiol (100 mcg/day) or placebo patch. Over 6 weeks, women completed weekly ratings on the Beck Depression Inventory (BDI), Edinburgh Postnatal Depression Scale (EPDS), and Hamilton Depression Scale (HAM-D). Primary outcome measures were treatment response (> 50% decrease from baseline BDI) and remission (BDI < 10) at 6 weeks, and secondary outcome measures included severity on all scales at weeks 3 and 6. Of 12 recruited women, 6 received TE and 6 received placebo. By week 6, 5 women receiving TE responded to treatment and 4 showed symptom remission, compared to 2 responders and 1 remitter in the placebo group. This difference was not significant (p = 0.24). In a mixed-model of BDI ratings, TE was associated with a 9.2 point decrease at 3 weeks (95%CI - 19.5 to + 1.0, p = 0.074) and a 10.5 point decrease at 6 weeks (95%CI - 21.0-0.0, p = 0.049) compared to placebo, though these differences did not survive multiple comparisons correction. Analogous effects were found for HAM-D but not EPDS scores. Interestingly, no significant difference in plasma estradiol levels existed between groups. We were unable to demonstrate a significant therapeutic benefit of TE compared with placebo in PPD. Although limited by under-recruitment and loss to follow-up, our results suggest TE is a feasible option for outpatient PPD management, with preliminary evidence (based on secondary outcomes) for efficacy. Therapeutic effects may be seen as early as 3 weeks and may not directly depend on peripheral measures of estradiol.

Cushing's syndrome.

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

Endometrial Effects of Prolonged Therapy with the Selective Progesterone Receptor Modulator Ulipristal Acetate: A Case Report.

BACKGROUND: Prolonged exposure to a selective progesterone receptor modulator (ulipristal acetate) in a patient with benign metastasizing leiomyoma did not result in endometrial hyperplasia or neoplasia. CASE: A woman with history of benign metastasizing leiomyoma underwent medical treatment for 5 years with ulipristal acetate. Endometrial biopsies were performed at established intervals to monitor for intraepithelial neoplasia or progesterone receptor modulator-associated endometrial changes (PAECs). The patient tolerated UPA therapy well; there was no evidence of hyperplasia or proliferative changes associated with progesterone-associated endometrial changes. CONCLUSION: In this case prolonged exposure to ulipristal acetate did not result in premalignant or malignant endometrial pathology.

Long-Term Outcome of Bilateral Laparoscopic Adrenalectomy Measured by Disease-Specific Questionnaire in a Unique Group of Patients with Cushing's Syndrome.

BACKGROUND: Laparoscopic bilateral adrenalectomy (LBA) is recommended for patients with bilateral adrenal disease and occult or unresectable ectopic Cushing's syndrome (CS). There are limited data on long-term outcomes after LBA, partly due to the lack of disease-specific tools for the measurement of impact on patients' health and quality of life. METHODS: We used a disease-specific questionnaire covering all major clinicopathologic characteristics of CS. We compared the outcome from LBA to a control group of 60 patients who had thyroidectomy (matched for age, gender, and time of surgery, 2:1 control-to-CS). RESULTS: Twenty-eight patients (20 women and 8 men) underwent LBA for CS. Of them, 24 patients (86 %) provided responses to our questionnaire. Ninety-two percent of patients' responses indicated a significant improvement of general Cushing's physical features with complete resolution reported in 59 % of responses. Significant improvement of associated biochemical abnormalities and comorbidities was reported in 83 % of patients' responses including complete reversal in 58 %. Significant improvement in emotional-behavioral symptoms was reported in 84 % of patients' responses with complete recovery in 53 %. All patients expressed satisfaction with LBA and significant improvement in their general health and self-reported quality of life. All of the improvements after LBA were statistically significant compared with the control group. CONCLUSIONS: Our disease-specific questionnaire enables a clearer understanding of the association between the clinical, metabolic, and emotional-behavioral features of CS, its treatment with LBA, and long-term impact on patient-reported quality of life. This disease-specific questionnaire may be useful for future studies in patients with CS.

Primary vs secondary adrenal insufficiency: ACTH-stimulated aldosterone diagnostic cut-off values by tandem mass spectrometry.

OBJECTIVES: To validate the diagnostic utility of Cortrosyn(™) stimulated aldosterone in the differentiation of primary (PAI) and secondary adrenal insufficiency (SAI) and to evaluate the effect of urine sodium levels and posture on test performance. DESIGN: Cross-sectional study. METHODS: Healthy volunteers (HV; n = 46) and patients with PAI (n = 26) and SAI (n = 29) participated in the study. Testing included cortisol and aldosterone (by liquid-chromatography tandem mass spectrometry) measurements at baseline and 30 and 60 min after 250 µg Cortrosyn(™). Plasma corticotropin (ACTH), renin activity (PRA) and urine spot sodium as a proxy for 24-h urine sodium excretion were measured at baseline. The effect of a sitting or semifowlers posture was evaluated in healthy volunteers. RESULTS: A Cortrosyn(™)-stimulated aldosterone level of 5 ng/dl (0·14 nmol/l) had 88% sensitivity and positive predictive value and 89·7% specificity and negative predictive value for distinguishing PAI from SAI. Spot urine sodium levels showed a strong correlation with peak aldosterone levels (r = -0·55, P = 0·02, n = 18) in the SAI but not PAI or HV groups. Posture did not have a significant effect on results. CONCLUSIONS: Once diagnosed with adrenal insufficiency, a stimulated aldosterone value of 5 ng/dl (0·14 nmol/l) works well to differentiate PAI from SAI. However, clinicians should be aware of the possible effect of total body sodium as reflected by spot urine sodium levels on aldosterone results. A 24-h urine sodium measurement may be helpful in interpretation.

Hypothalamic-pituitary-adrenal axis in lethal canine Staphylococcus aureus pneumonia.

The clinical significance and even existence of critical illness-related corticosteroid insufficiency is controversial. Here, hypothalamic-pituitary-adrenal (HPA) function was characterized in severe canine Staphylococcus aureus pneumonia. Animals received antibiotics and titrated life-supportive measures. Treatment with dexamethasone, a glucocorticoid, but not desoxycorticosterone, a mineralocorticoid, improves outcome in this model. Total and free cortisol, adrenocorticotropic hormone (ACTH). and aldosterone levels, as well as responses to exogenous ACTH were measured serially. At 10 h after the onset of infection, the acute HPA axis stress response, as measured by cortisol levels, exceeded that seen with high-dose ACTH stimulation but was not predictive of outcome. In contrast to cortisol, aldosterone was largely autonomous from HPA axis control, elevated longer, and more closely associated with survival in early septic shock. Importantly, dexamethasone suppressed cortisol and ACTH levels and restored ACTH responsiveness in survivors. Differing strikingly, nonsurvivors, sepsis-induced hypercortisolemia, and high ACTH levels as well as ACTH hyporesponsiveness were not influenced by dexamethasone. During septic shock, only serial measurements and provocative testing over a well-defined timeline were able to demonstrate a strong relationship between HPA axis function and prognosis. HPA axis unresponsiveness and high aldosterone levels identify a septic shock subpopulation with poor outcomes that may have the greatest potential to benefit from new therapies.

A Rare Cyclic Cushing Syndrome Mystery Illustrates Diagnostic Principles.

Pheochromocytomas predominantly produce catecholamines, and rarely also produce ACTH, causing Cushing syndrome (CS). Cyclic CS, an uncommon presentation of hypercortisolism, poses a diagnostic challenge. We report a 71-year-old woman who developed cyclic ectopic ACTH secretion from a pheochromocytoma. Previous evaluations showed intermittent elevations in cortisol and ACTH levels, normal pituitary magnetic resonance imaging, and an adrenal nodule. On admission, she was hypertensive and had cushingoid features. Bilateral inferior petrosal sinus sampling with desmopressin stimulation and an 8-mg dexamethasone suppression test suggested ectopic ACTH secretion, but ACTH increased during the peripheral desmopressin stimulation test. Plasma normetanephrines were about 2-fold above the upper reference limit. 18F-fluoro-dopa and 68Gallium-DOTATATE positron emission tomography/computed tomography scans, computed tomography, and magnetic resonance imaging identified an adrenal mass. After doxazosin adrenoceptor blockade, she underwent right adrenalectomy; histopathology and immunohistochemistry confirmed an ACTH-secreting pheochromocytoma. Postoperative blood pressure normalized and serum cortisol and plasma ACTH levels were suppressed, requiring physiologic hydrocortisone replacement. This case underscores the importance of considering pheochromocytoma in ACTH-dependent hypercortisolism with elevated metanephrines and an adrenal mass. Timely diagnosis and treatment can reduce morbidity and improve quality of life.

Ovine CRH Stimulation and 8 mg Dexamethasone Suppression Tests in 323 Patients With ACTH-Dependent Cushing's Syndrome.

CONTEXT: Determining the etiology of adrenocorticotropin (ACTH)-dependent Cushing's syndrome (CS) is often difficult. The gold standard test, inferior petrosal sinus sampling (IPSS), is expensive and not widely available. OBJECTIVE: Evaluate the performance of the corticotropin-releasing hormone stimulation test (CRH-ST) and the 8 mg high-dose dexamethasone suppression test (HDDST) in distinguishing Cushing's disease (CD) from ectopic ACTH syndrome (EAS). METHODS: Retrospective review in a tertiary referral center. A total of 323 patients with CD or EAS (n = 78) confirmed by pathology or biochemical cure (n = 15) in 96% underwent CRH-ST and HDDST performed between 1986 and 2019. We calculated test sensitivity (Se), specificity (Sp), positive predictive value (PPV), negative predictive value, and diagnostic accuracy (DA) for the diagnosis of CD, and determined optimal response criteria for each test, alone and in combination. RESULTS: The CRH-ST performed better than the HDDST (DA 91%, 95% CI 87-94% vs 75%, 95% CI 69-79%). Optimal response criteria were a ≥40% increase of ACTH and/or cortisol during the CRH test and a ≥69% suppression of cortisol during the HDDST. A ≥40% cortisol increase during the CRH test was the most specific measure, PPV 99%. Seventy-four percent of subjects had concordant positive CRH test and HDDST results, yielding Se 93%, Sp 98%, DA 95%, and PPV 99%, with a pretest likelihood of 85%. A proposed algorithm diagnosed 64% of patients with CD with near perfect accuracy (99%), obviating the need for IPSS. CONCLUSION: CRH is a valuable tool to correctly diagnose the etiology of ACTH-dependent CS. Its current worldwide unavailability impedes optimal management of these patients.

Cortisol and ACTH Measurements at Extubation From Pituitary Surgery Predicts Hypothalamic-Pituitary-Adrenal Axis Function.

Context: Early prediction of hypothalamic-pituitary-adrenal (HPA) axis function following transsphenoidal surgery (TSS) can improve patient safety and reduce costs. Objective: Systematic measurement of ACTH and cortisol at extubation following anesthesia to predict remission from Cushing's disease (CD) and HPA axis preservation following non-CD surgery. Design: Retrospective analysis of clinical data between August 2015 and May 2022. Setting: Referral center. Patients: Consecutive patients (n = 129) undergoing TSS who had perioperative ACTH and cortisol measurements. Interventions: ACTH and cortisol measurement at extubation. Further serial 6-hourly measurements in CD patients. Main outcome measures: Prediction of future HPA axis status based on ACTH/cortisol at extubation. Results: ACTH and cortisol increased sharply in all patients at extubation. CD patients (n = 101) had lower ACTH values than non-CD patients (110.1 vs 293.1 pg/mL; P < 0.01). In non-CD patients, lower plasma ACTH at extubation predicted the need for eventual corticosteroid replacement (105.8 vs 449.1 pg/mL, P < 0.01). In CD patients, the peak post-extubation cortisol at 6 hours was a robust predictor for nonremission (60.7 vs 219.2 µg/dL, P = 0.03). However, normalized early postoperative value (NEPV; the post-extubation values minus the peak preoperative CRH or desmopressin test values) of cortisol reliably distinguished nonremission earlier, at the time of extubation (-6.1 vs 5.9, P = 0.01), and later. Conclusions: We found that at extubation following TSS, ACTH can predict the need for eventual steroid replacement in non-Cushing's patients. In patients with CD, we found a robust prediction of nonremission with NEPV cortisol at extubation and later.

Diurnal Range and Intra-patient Variability of ACTH Is Restored With Remission in Cushing's Disease.

CONTEXT: Single ACTH measurements have limited ability to distinguish patients with Cushing's disease (CD) from those in remission or with other conditions. OBJECTIVE: To investigate the changes in ACTH levels before and after transsphenoidal surgery (TSS) to identify trends that could confirm remission from CD and help establish ACTH cutoffs for targeted clinical trials in CD. DESIGN: Retrospective analysis of CD patients who underwent TSS from 2005 to -2019. SETTING: Referral center. PATIENTS: CD patients (n = 253) with ACTH measurements before and after TSS. INTERVENTIONS: TSS for CD. MAIN OUTCOME MEASURES: Remission after TSS. RESULTS: Remission was observed in 223 patients after TSS. Those in remission had higher ACTH variability at AM (P = .02) and PM (P < .001) time points compared to nonremission. The nonremission group had a significantly narrower diurnal range compared to the remission group (P = <.0001). A decrease in plasma ACTH of ≥50% from mean preoperative levels predicted CD remission after TSS, especially when using PM values. The absolute plasma ACTH concentration and ratio of preoperative to postoperative values were significantly associated with nonremission after multivariable logistic regression (adj P < .001 and .001, respectively). CONCLUSIONS: Our findings suggest that ACTH variability is suppressed in CD, and remission from CD is associated with the restoration of this variability. Furthermore, a decrease in plasma ACTH by 50% or more may serve as a predictor of remission post-TSS. These insights could guide clinicians in developing rational outcome measures for interventions targeting CD adenomas.

Pituitary adenoma or neuroendocrine tumour: the need for an integrated prognostic classification.

In the 2022 fifth edition of the WHO Classification of Endocrine Tumours and of Central Nervous System Tumours, pituitary adenomas are reclassified as neuroendocrine tumours (NETs). This change confers an oncology label to neoplasms that are overwhelmingly benign. A comprehensive clinical classification schema is required to guide prognosis, therapy and outcomes for all patients with pituitary adenomas. Pituitary adenomas and NETs exhibit some morphological and ultrastructural similarities. However, unlike NETs, pituitary adenomas are highly prevalent, yet indolent and rarely become malignant. This Perspective presents the outcomes of an interdisciplinary international workshop that addressed the merit and clinical implications of the classification change of pituitary adenoma to NET. Many non-histological factors provide mechanistic insight and influence the prognosis and treatment of pituitary adenoma. We recommend the development of a comprehensive classification that integrates clinical, genetic, biochemical, radiological, pathological and molecular information for all anterior pituitary neoplasms.

Cushing's syndrome in multiple endocrine neoplasia type 1.

OBJECTIVE: In patients with multiple endocrine neoplasia type 1 (MEN1), Cushing's syndrome (CS) from endogenous hypercortisolism can result from pituitary, adrenal or other endocrine tumours. The purpose of this study was to characterize the range of presentations of CS in a large series of MEN1 patients. DESIGN: Retrospective review of NIH Clinical Center inpatient records over an approximately 40-year period. PATIENTS: Nineteen patients (eight males, 11 females) with CS and MEN1. MEASUREMENTS: Biochemical, imaging, surgical and pathological findings. RESULTS: An aetiology was determined for 14 of the 19 patients with CS and MEN1: 11 (79%) had Cushing's disease (CD) and three (21%) had ACTH-independent CS owing to adrenal tumours, frequencies indistinguishable from sporadic CS. Three of 11 MEN1 patients with CD (27%) had additional non-ACTH-secreting pituitary microadenomas identified at surgery, an incidence 10-fold higher than in sporadic CD. Ninety-one per cent of MEN1 patients with CD were cured after surgery. Two of three MEN1 patients with ACTH-independent CS (67%) had adrenocortical carcinoma. One patient with adrenal cancer and another with adrenal adenoma were cured by unilateral adrenalectomy. No case of ectopic ACTH secretion was identified in our patient cohort. The aetiology of CS could not be defined in five patients; in three of these, hypercortisolism appeared to resolve spontaneously. CONCLUSIONS: The tumour multiplicity of MEN1 can be reflected in the anterior pituitary, MEN1-associated ACTH-independent CS may be associated with aggressive adrenocortical disease and an aetiology for CS in MEN1 may be elusive in a substantial minority of patients.

Selective progesterone receptor modulators and reproductive health.

PURPOSE OF REVIEW: This review is intended to provide perspective on the history of selective progesterone receptor modulators (SPRMs) and progesterone antagonists, their current availability, therapeutic promise and safety concerns. RECENT FINDINGS: Despite keen interest in synthesis of these compounds, only a handful have had clinical test results allowing for commercialization. Mifepristone is well tolerated and effective for single dose first trimester at-home pregnancy termination and is available in much of the world. Ulipristal acetate, at single doses, is well tolerated and effective for emergency contraception, with less availability. Chronic use of these agents has been associated with abnormal liver enzymes, and rarely, with hepatic failure; causality is not understood. SUMMARY: SPRMs and progesterone antagonists have great therapeutic promise for use in other reproductive disorders, including breast cancer, endometriosis, adenomyosis, estrogen-free contraception and cervical ripening but require additional study. Alternative formulations, whether local (topical breast or intrauterine) or extended-release may reduce the incidence of liver function abnormalities and should be explored.

Molecular Derangements and the Diagnosis of ACTH-Dependent Cushing's Syndrome.

Endogenous Cushing's syndrome (CS) is associated with morbidities (diabetes, hypertension, clotting disorders) and shortens life because of infections, pulmonary thromboembolism, and cardiovascular disease. Its clinical presentation is immensely variable, and diagnosis and treatment are often delayed. Thus, there are many opportunities for basic and clinical research leading to better tests, faster diagnosis, and optimized medical treatments. This review focuses on CS caused by excessive adrenocorticotropin (ACTH) production. It describes current concepts of the regulation of ACTH synthesis and secretion by normal corticotropes and mechanisms by which dysregulation occurs in corticotrope (termed "Cushing's disease") and noncorticotrope (so-called ectopic) ACTH-producing tumors. ACTH causes adrenal gland synthesis and pulsatile release of cortisol; the excess ACTH in these forms of CS leads to the hypercortisolism of endogenous CS. Again, the differences between healthy individuals and those with CS are highlighted. The clinical presentations and their use in the interpretation of CS screening tests are described. The tests used for screening and differential diagnosis of CS are presented, along with their relationship to cortisol dynamics, pathophysiology, and negative glucocorticoid feedback regulation in the two forms of ACTH-dependent CS. Finally, several gaps in current understanding are highlighted in the hope of stimulating additional research into this challenging disorder.