The diagnosis of Cushing's syndrome

Cortisol: Analytical and clinical determinants

Cortisol, the main human glucocorticoid, is synthesized from cholesterol in the adrenal cortex and predominantly metabolized by the liver. Interpretation of quantitative results from the analysis of serum, urine and saliva is complicated by variation in circadian rhythm, response to stress as well as the presence of protein-bound and free forms. Interestingly, cortisol is the only hormone routinely measured in serum, urine, and saliva. Preanalytical and analytical challenges arise in each matrix and are further compounded by the use of various stimulation and suppression tests commonly employed in clinical practice. Although not yet included in clinical guidelines, measurement of cortisol in hair may be of interest in specific situations. Immunoassays are the most widely used methods in clinical laboratories to measure cortisol, but they are susceptible to interference from synthetic and endogenous steroids, generally producing a variable overestimation of true cortisol results, especially in urine. Analysis by mass spectrometry provides higher specificity and allows simultaneous measurement of multiple steroids including synthetic steroids, thus reducing diagnostic uncertainty. An integrated review of cortisol in various disease states is also addressed.

Sensitivity of Different ACTH and Cortisol Concentration Values in Corticotropin-Releasing Hormone Based Tests in Cushing's Disease

PURPOSE

In Cushing's disease (CD) patients, the aim of the present study is to confirm sensitivity of several ACTH and cortisol concentration values in different time points, during corticotropin-releasing hormone (CRH) stimulation test and during CRH stimulation following dexamethasone suppression (DEX-CRH) test.

METHODS

We retrospectively analyzed cortisol and ACTH concentration increment during CRH and DEX-CRH tests in 23 patients with confirmed CD. Cortisol and ACTH concentrations were determined immediately before, 15 min and 30 min after CRH stimulation. We evaluated the sensitivity of different cutoff values including those reported in previous studies, in the diagnosis of CD.

RESULTS

During DEX-CRH test, 15 min serum cortisol concentration of 1.4 μg/dl (38 nmol/L) had a sensitivity of 90.9%, and serum cortisol concentration ≥1.27 μg/dl (35 nmol/L) had a sensitivity of 100%. For plasma ACTH, sensitivity of 100% was obtained using ACTH ≥3.5pmol/L (16 pg/ml) at 30 min. During CRH test, 35% increase from baseline in ACTH concentration had a sensitivity of 72.7%. Twenty percent increase in cortisol 30 minutes after stimulation yielded a sensitivity of 85.7%. The best sensitivity of ACTH and cortisol increment was obtained 15 min after stimulation, using 19% and 9% increase, respectively (sensitivity of 100% and 92.8%, respectively).

CONCLUSION

During CRH and DEX-CRH tests, the study findings agree with the good sensitivity of ACTH and cortisol cutoff values suggested in previous studies; yet, other cutoff values may give a higher diagnostic sensitivity.

Cushing's syndrome in women: age-related differences in etiology and clinical picture

OBJECTIVE

To evaluate the clinical presentation, biochemical profile, and etiology of Cushing's syndrome (CS) in women stratified by age.

METHODS

Retrospective study of patients with CS, treated at Rabin Medical Center from 2000 to 2020, or Maccabi Healthcare Services in Israel from 2005 to 2017. Disease etiology, presentation and biochemical profile were compared according to age at diagnosis: ≤ 45, 46-64, or ≥ 65 years. Study was approved by the Ethics Review Boards of both facilities with waiver of consent.

RESULTS

The cohort included 142 women (mean age, 46.0 ± 15.1 years):81 (57.0%) with Cushing's disease (CD), and 61 (43.0%) with adrenal CS. Pituitary etiology was more common among women < 45 (70.6%), compared with patients ≥ 65 years (31.6%) (P < 0.05). Among CS patients, hypercortisolism was diagnosed in the context of screening after an adrenal incidentaloma detection in 15.0% of patients < 45 and 53.8% of ≥ 65 years (P < 0.001). Weight gain was evident in 57.4% of women < 45 (56.3% CD, 60.0% CS), and 15.8% of women ≥ 65 years (50% CD, 0% CS) (P = 0.011). Mean UFC levels were highest for women < 45 (3.8 × ULN) and lowest for ≥ 65 years (2.3 × ULN) (P < 0.001).

CONCLUSION

We have shown for the first time that women with CS ≥ 65 years of age more commonly have adrenal etiology. The initial presentation of CS also differs between age groups, where women < 45 years are likely to present with weight gain, while those ≥ 65 years are frequently diagnosed incidentally, when screening for hypercortisolism in the presence of an adrenal incidentaloma.

Successful resolution of ectopic Cushing syndrome by minimally invasive thoracoscopic resection of the neuroendocrine tumor of the thymus: a rare case report

Background

Ectopic Cushing syndrome (ECS) is a sporadic condition. Even uncommon is an ECS that derives from a carcinoid tumor of the thymus. These tumors may pose several diagnostic and therapeutic conundrums. This report discusses the differential diagnosis, clinicopathological findings, and effective treatment of a rare case of ECS using a minimally invasive approach.

Case presentation

A 29-year-old woman with Cushing syndrome presented with facial flushing. Physical examination revealed hypertension (blood pressure: 141/100 mmHg). A mediastinal tumor was discovered to be the cause of the patient’s chronic hypokalemia and hypercortisolemia. Cortisol levels increased in the morning, reaching 47.7 ug/dL. The levels of the hormones ACTH, aldosterone, and renin were determined to be 281 pg/mL, 3.0 ng/dL, and 2.1 pg/mL, respectively. The presence of hypertension, hypokalemia, and alkalinity suggested Cushing’s syndrome, which was proven to be ACTH-dependent ECS by a dexamethasone suppression test. A chest CT scan revealed inflammation in the posterior basal region of the right lower lobe. The superior anterior mediastinum was characterized by round-shaped isodensity lesions with distinct borders. She underwent thoracoscopic anterior mediastinal tumor excision via the subxiphoid technique (R0 resection); following surgery, her blood pressure returned to normal, and the hypernatremia/hypopotassemia resolved. The tumor was determined to be a thymic carcinoid. Most notably, cortisol levels fell to half of their presurgical levels after one hour of surgery, and other abnormalities corrected substantially postoperatively.

Conclusion

Thoracoscopic excision of thymic tumors by subxiphoid incision may be a useful treatment option for ECS caused by neuroendocrine tumors of the thymus

Glucocorticoid Withdrawal Syndrome following treatment of endogenous Cushing Syndrome

PURPOSE

Literature regarding endogenous Cushing syndrome (CS) largely focuses on the challenges of diagnosis, subtyping, and treatment. The enigmatic phenomenon of glucocorticoid withdrawal syndrome (GWS), due to rapid reduction in cortisol exposure following treatment of CS, is less commonly discussed but also difficult to manage. We highlight the clinical approach to navigating patients from GWS and adrenal insufficiency to full hypothalamic-pituitary-adrenal (HPA) axis recovery.

METHODS

We review the literature on the pathogenesis of GWS and its clinical presentation. We provide strategies for glucocorticoid dosing and tapering, HPA axis testing, as well as pharmacotherapy and ancillary treatments for GWS symptom management.

RESULTS

GWS can be difficult to differentiate from adrenal insufficiency and CS recurrence, which complicates glucocorticoid dosing and tapering regimens. Monitoring for HPA axis recovery requires both clinical and biochemical assessments. The most important intervention is reassurance to patients that GWS symptoms portend a favorable prognosis of sustained remission from CS, and GWS typically resolves as the HPA axis recovers. GWS also occurs during medical management of CS, and gradual dose titration based primarily on symptoms is essential to maintain adherence and to eventually achieve disease control. Myopathy and neurocognitive dysfunction can be chronic complications of CS that do not completely recover.

CONCLUSIONS

Due to limited data, no guidelines have been developed for management of GWS. Nevertheless, this article provides overarching themes derived from published literature plus expert opinion and experience. Future studies are needed to better understand the pathophysiology of GWS to guide more targeted and optimal treatments.

MRI-Negative Cushing's Disease: A Review on Therapeutic Management

OBJECTIVES

In this systematic review and meta-analysis, we review the literature regarding patients with Cushing's disease (CD) with negative or inconclusive magnetic resonance imaging (MRI).

METHODS

A quantitative systematic review was performed. Article selection was performed by searching MEDLINE (using PubMed), EMBASE, and Cochrane electronic bibliographic databases.

RESULTS

28 articles described surgical management of inconclusive MRI or MRI-negative CD. A total of 858 patients underwent surgery for their Cushing adenoma. Different types of surgery, including endoscopic endonasal transsphenoidal surgery (EETS) (190 cases) and microscopic endonasal transsphenoidal surgery (METS) (488 cases), were performed on patients with MRI-negative CD. 7 studies, which included 164 patients, did not describe any surgery. EETS and METS are conducted to achieve selective adenomectomy (231 cases), partial adenomectomy (80 cases), total adenomectomy (13 cases), hemihypophysectomy (15 cases), or enlarged adenomectomy (48 cases). Based on available data on these studies, the remission rate, persistence rate, and recurrence rate after different types of surgeries on patients with MRI-negative CD were 72.97%, 27.03%, and 12.05%, respectively. There was no statistically significant difference between EETS and METS in the subanalysis regarding recurrence rate, remission rate, and persistence rate. However, the recurrence rate in the METS group is almost 3 times higher than in the EETS group.

CONCLUSIONS

Surgery has a good prognosis in patients with MRI-negative CD in terms of remission, and EETS has a lower rate of disease recurrence than METS; therefore, EETS seems to be the potential recommended treatment technique, while to confirm the therapeutic method of choice, further investigations should be done.

Consensus on diagnosis and management of Cushing's disease: a guideline update

Cushing's disease requires accurate diagnosis, careful treatment selection, and long-term management to optimise patient outcomes. The Pituitary Society convened a consensus workshop comprising more than 50 academic researchers and clinical experts to discuss the application of recent evidence to clinical practice. In advance of the virtual meeting, data from 2015 to present about screening and diagnosis; surgery, medical, and radiation therapy; and disease-related and treatment-related complications of Cushing's disease summarised in recorded lectures were reviewed by all participants. During the meeting, concise summaries of the recorded lectures were presented, followed by small group breakout discussions. Consensus opinions from each group were collated into a draft document, which was reviewed and approved by all participants. Recommendations regarding use of laboratory tests, imaging, and treatment options are presented, along with algorithms for diagnosis of Cushing's syndrome and management of Cushing's disease. Topics considered most important to address in future research are also identified.

DHEAS and Differential Blood Counts as Indirect Signs of Glucocorticoid Excess in Adrenal Non-Producing Adenomas

The majority of incidentally discovered adrenal tumors are later characterized as non-producing adrenocortical adenomas (NPA). We asked whether laboratory abnormalities in parameters that reflect glucocorticoid action can be found in patients with NPA despite their nature of being clinically unapparent. Since glucocorticoids are potent immunosuppressants we studied blood counts and differential blood counts along with corticotropin and dehydroepiandrostenedione sulfate (DHEAS) blood concentrations, as well as cortisol values before and after an overnight 1 mg dexamethasone suppression test. We compared the results of normal individuals, of patients with adrenal adenomas and normal hormone profiles and with subclinical autonomous glucocorticoid hypersecretion, as well as overt cortisol excess. We found that almost all indices of the blood counts were significantly different between the patients groups. In particular, patients with adrenal non-producing adenomas already showed signs of glucocorticoid excess, including relative lymphocytopenia, lowered DHEAS, and ACTH concentrations than control individuals. We also found that the extent of lymphocytopenia correlated with the concentrations of DHEAS and ACTH, and DHEAS correlated well with ACTH. We conclude that the basal ACTH and DHEAS values along with the differential blood counts give good information on the extent of glucocorticoid excess and that silent adrenal adenomas seem to oversecrete glucocorticoids at concentrations that already alter these parameters.

Diabetes, Active Disease, and Afternoon Serum Cortisol Levels Predict Cushing's Disease Mortality: A Cohort Study

CONTEXT

Cushing's disease (CD) is a life-threating disease, with increased mortality in comparison with the general population.

OBJECTIVE

This study aimed to evaluate standardized mortality ratios (SMRs) in CD patients. We also analyzed independent risk factors related to increased mortality.

DESIGN

We conducted a longitudinal cohort study in a 3rd level specialty center, from 1979 to 2018, in patients with CD.

RESULTS

From 1375 cases with a pathology diagnosis of pituitary adenoma, 191 cases had the confirmed diagnosis of CD (14%). A total of 172 patients completed follow-up, with a mean age at diagnosis of 33 ± 11 years, female predominance (n = 154, 89.5%), majority of them with microadenoma (n = 136, 79%), and a median follow-up of 7.5 years (2.4-15). Eighteen patients (10.5%) died, 8 of them (44%) were with active CD, 8 (44%) were under remission, and 2 (11%) were under disease control. Estimated all-cause SMR = 3.1, 95% confidence interval (CI) 1.9-4.8, P < 0.001. Cardiovascular disease was the main cause of death (SMR = 4.2, 1.5-9.3, P = 0.01). Multivariate Cox regression models adjusted for potential cofounders showed that diabetes (HR = 5.2, IC 95% 1.8-15.4, P = 0.002), high cortisol levels after 1600 hours at diagnosis (3.4, 2.3-7.0, P = 0.02), and active CD (7.5, 3.8-17.3, P = 0.003) significantly increased the risk of mortality.

CONCLUSIONS

Main cause of CD mortality was cardiovascular disease. Main risk factors for mortality were uncontrolled diabetes, persistently high cortisol levels after 1600 hours at diagnosis, and active disease at last follow-up.

The definition of remission and recurrence of Cushing's disease

Accurate classification of postsurgical remission, and early recognition of recurrence are crucial to timely treat and prevent excess mortality in Cushing's Disease, yet the criteria used to define remission are variable and there is no consensus to define recurrence. Remission is defined as postsurgical hypocortisolemia, but delayed remission may occur. Recurrence is the return of clinical manifestations with biochemical evidence of hypercortisolism. The proper combination of tests and their timing are controversial. Reliable predicting tools may lead to earlier diagnosis upon recurrence. Many factors have been studied independently for prediction with variable performance. Novel artificial intelligence approaches seek to integrate these variables into risk calculators and machine-learning algorithms with an acceptable short-term predictive performance but lack longer-term accuracy. Prospective studies using these approaches are needed. This review summarizes the evidence behind the definitions of remission and recurrence and provide an overview of the available tools to predict and/or diagnose them.

Secondary thoracolumbar deformity and sagittal imbalance due to osteoporosis in a young man with Cushing's disease: A case report

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Vertebral fractures are frequent due to osteoporosis in Cushing disease.

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Treating de primary cause of the disease reduces the risk of new fractures.

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Surgical treatment may be needed for secondary deformity.

Introduction

To describe an unusual case of Cushing’s disease with spontaneous axial pain due to multiple consecutive vertebral fractures which led to secondary deformity that required surgical treatment.

Presentation of case

A 43-year-old man was referred to our service with back pain without previous trauma. He was diagnosed of refractory arterial hypertension and we observed centripetal obesity during exploration. With clinical findings and laboratory studies, ACTH-dependent Cushing’s syndrome due to a pituitary microadenoma was diagnosed and the patient underwent an endoscopic-assisted endonasal transsphenoidal resection. Dual energy X-ray absorptiometry (DXA) revealed spine and hip osteoporosis. Moreover, X-ray, MR and CT showed multiple vertebral osteoporotic compression fractures in thoracic and thoracolumbar area. Secondary kyphosis thoracolumbar deformity and sagittal imbalance was treated by two-level Smith-Petersen osteotomies (SPO) and instrumented posterolateral arthrodesis T10-L3 using fenestrated pedicles screws with polymethyl methacrylate (PMMA). At six years of follow-up dual energy X-ray absorptiometry (DXA) recovered normal values (T-score lumbar spine L2–L4 1.4 and T-score hip -1.9) and X-ray study showed an adequate sagittal vertebral axis.

Discussion

Osteoporosis is a common feature of CD and fractures occur in 30–50% of cases. Treating the underlying cause reduces the risk of new fractures. Medical therapy is usually enough but consecutive multiple vertebral fractures related to glucocorticoid excess may lead to secondary painful deformity.

Conclusion

Vertebral compression fractures result from secondary corticoid-induced osteoporosis in Cushing’s disease. Early detection and treatment of primary disease decreases the risk of new fractures. However, unusual secondary spinal deformity or disability may require surgery.

Management of patients with persistent or recurrent Cushing's disease after initial pituitary surgery

INTRODUCTION

Treatment options for persistent and recurrent Cushing's disease (CD) include an individualized approach for repeat surgery, medical treatment, radiation therapy (RT), and bilateral adrenalectomy (BLA).

AREAS COVERED

In this expert opinion perspective, the authors review the latest treatment(s) for persistent/recurrent CD. A PubMed search was undertaken (English articles through May 2020) and relevant articles discussed. Repeat pituitary surgery should be considered in most patients with proven hypercortisolism; there is potential for cure with low risk of major complications. Medical therapy is valuable either alone, while awaiting the effects of RT, or in preparation for BLA. Medical therapy includes steroidogenesis inhibitors, agents that act at the pituitary or glucocorticoid receptor level, and novel agents in development. Radiation therapy has been used successfully to treat CD, but hypopituitarism risk and delayed efficacy (improved with radiosurgery) are major drawbacks. Laparoscopic BLA is safe and effective in patients with severe, difficult-to-manage hypercortisolism, but long-term follow-up is required as corticotroph tumor progression can develop.

EXPERT OPINION

Treatment of persistent/recurrent CD is challenging. Most patients require >1 therapy to achieve long-lasting remission. There is currently no ideal single treatment option that provides high and rapid efficacy, low adverse effects, and preserves normal pituitary-adrenal axis function.

Dynamic changes of views on the brain changes of Cushing's syndrome using different computer-assisted tool

Cushing's syndrome (CS) provides a unique model for assessing the neurotoxic effect of chronic hypercortisolism on human brains. With the ongoing development of different computer-assisted tools, four research stages emerged, each with its own pearls and pitfalls. This review summarizes current knowledge and describes the dynamic changes of views on the brain changes of CS, especially in the current era of the rapid development of artificial intelligence and big data. The adverse effects of GC on brain are proven to be on structural, functional and cellular levels at the same time.

Circadian rhythms: a possible new player in non-alcoholic fatty liver disease pathophysiology

Over the last decades, a better knowledge of the molecular machinery supervising the regulation of circadian clocks has been achieved, and numerous findings have helped in unravelling the outstanding significance of the molecular clock for the proper regulation of our physiologic and metabolic homeostasis. Non-alcoholic fatty liver disease (NAFLD) is currently considered as one of the emerging liver pathologies in the Western countries due to the modification of eating habits and lifestyle. Although NAFLD is considered a pretty benign condition, it can progress towards non-alcoholic steatohepatitis (NASH) and eventually hepatocellular carcinoma (HCC). The pathogenic mechanisms involved in NAFLD development are complex, since this disease is a multifactorial condition. Major metabolic deregulations along with a genetic background are believed to take part in this process. In this light, the aim of this review is to give a comprehensive description of how our circadian machinery is regulated and to describe to what extent our internal clock is involved in the regulation of hormonal and metabolic homeostasis, and by extension in the development and progression of NAFLD/NASH and eventually in the onset of HCC.

Paraneoplastic syndromes and other systemic disorders associated with neuroendocrine neoplasms

Neuroendocrine paraneoplastic syndromes (PNS) consist of metabolic disorders that accompany benign and malignant neoplasms but remain unrelated to mass effects or invasion by the primary tumor or its metastases. The underlying pathogenesis responsible for PNS usual clinical presentation relies on aberrant production of protein hormones, proteins and other substances by the tumor. Prompt recognition of characteristic signs and symptoms combined with serological identification of key substances may result in early diagnosis of PNS and its underlying malignancy. For these reasons, healthcare professionals should familiarize themselves with tumor-induced hypercalcemia, syndrome of inappropriate antidiuretic hormone, carcinoid syndrome, virilisation syndrome, gynecomastia, acromegaly, Cushing syndrome, osteogenic osteomalacia, tumor-induced hypoglycemia, necrolytic migratory erythema, and watery diarrhea, hypokalemia and achlorydria syndrome. Medical awareness for PNS can improve patient outcomes through earlier administration of cancer therapy and treatment, better symptomatic relief and prolong overall survival.

Hypercortisolemia Recurrence in Cushing's Disease; a Diagnostic Challenge

Cushing's disease recurrence following successful pituitary surgery is common and merits prompt and careful diagnosis, as untreated hypercortisolism leads to increased morbidity and mortality. However, an established recurrence definition has not been forthcoming. This poses a diagnostic challenge especially early in the course of returning hypercortisolemia and/or in the presence of non-neoplastic hypercortisolemia. A late-night salivary cortisol (LNSC) test is the first test to reveal abnormal results, however, has limitations related to assay performance as well as individual patient variability. Dexamethasone suppression tests and 24-h urinary free cortisol (UFC) results are next to reveal abnormal results. Other tests including, corticotropin-releasing hormone (CRH) stimulation test and combined CRH-dexamethasone test, as well as desmopressin stimulation test with/without dexamethasone are also used, although, none have proven to be the preeminent diagnostic test for recurrence determination. There is a possible role for these tests in predicting recurrence in patients who have experienced remission, though, this also remains challenging due to lack of established cutoff values. This article details and summarizes evidence about different diagnostic tests currently used to diagnose and predict Cushing's disease recurrence.

Adrenocortical Challenge Response and Genomic Analyses in Scottish Terriers With Increased Alkaline Phosphate Activity

Scottish terriers (ST) frequently have increased serum alkaline phosphatase (ALP) of the steroid isoform. Many of these also have high serum concentrations of adrenal sex steroids. The study's objective was to determine the cause of increased sex steroids in ST with increased ALP. Adrenal gland suppression and stimulation were compared by low dose dexamethasone (LDDS), human chorionic gonadotropin (HCG) and adrenocorticotropic hormone (ACTH) response tests. Resting plasma pituitary hormones were measured. Steroidogenesis-related mRNA expression was evaluated in six ST with increased ALP, eight dogs of other breeds with pituitary-dependent hyperadrenocorticism (HAC), and seven normal dogs. The genome-wide association of single nucleotide polymorphisms (SNP) with ALP activity was evaluated in 168 ST. ALP (reference interval 8–70 U/L) was high in all ST (1,054 U/L) and HAC (985 U/L) dogs. All HAC dogs and 2/8 ST had increased cortisol post-ACTH administration. All ST and 2/7 Normal dogs had increased sex steroids post-ACTH. ST and Normal dogs had similar post-challenge adrenal steroid profiles following LDDS and HCG. Surprisingly, mRNA of hydroxysteroid 17-beta dehydrogenase 2 (HSD17B2) was lower in ST and Normal dogs than HAC. HSD17B2 facilities metabolism of sex steroids. A SNP region was identified on chromosome 5 in proximity to HSD17B2 that correlated with increased serum ALP. ST in this study with increased ALP had a normal pituitary-adrenal axis in relationship to glucocorticoids and luteinizing hormone. We speculate the identified SNP and HSD17B2 gene may have a role in the pathogenesis of elevated sex steroids and ALP in ST.

Should Cushing's Syndrome be Considered as a Disease with High Cardiovascular Risk in Relevant Guidelines?

A considerable amount of data supports a 1.8-7.4-fold increased mortality associated with Cushing's syndrome (CS). This is attributed to a high occurrence of several cardiovascular disease (CVD) risk factors in CS [e.g. adiposity, arterial hypertension (AHT), dyslipidaemia and type 2 diabetes mellitus (T2DM)]. Therefore, practically all patients with CS have the metabolic syndrome (MetS), which represents a high CVD risk. Characteristically, despite a relatively young average age, numerous patients with CS display a 'high' or 'very high' CVD risk (i.e. risk of a major CVD event >20% in the following 10 years). Although T2DM is listed as a condition with a high CVD risk, CS is not, despite the fact that a considerable proportion of the CS population will develop T2DM or impaired glucose tolerance. CS is also regarded as a risk factor for aortic dissection in current guidelines. This review considers the evidence supporting listing CS among high CVD risk conditions.

Heat Stress Modulates Both Anabolic and Catabolic Signaling Pathways Preventing Dexamethasone-Induced Muscle Atrophy In Vitro

It is generally recognized that synthetic glucocorticoids induce skeletal muscle weakness, and endogenous glucocorticoid levels increase in patients with muscle atrophy. It is reported that heat stress attenuates glucocorticoid-induced muscle atrophy; however, the mechanisms involved are unknown. Therefore, we examined the mechanisms underlying the effects of heat stress against glucocorticoid-induced muscle atrophy using C2C12 myotubes in vitro, focusing on expression of key molecules and signaling pathways involved in regulating protein synthesis and degradation. The synthetic glucocorticoid dexamethasone decreased myotube diameter and protein content, and heat stress prevented the morphological and biochemical glucocorticoid effects. Heat stress also attenuated increases in mRNAs of regulated in development and DNA damage responses 1 (REDD1) and Kruppel-like factor 15 (KLF15). Heat stress recovered the dexamethasone-induced inhibition of PI3K/Akt signaling. These data suggest that changes in anabolic and catabolic signals are involved in heat stress-induced protection against glucocorticoid-induced muscle atrophy. These results have a potentially broad clinical impact because elevated glucocorticoid levels are implicated in a wide range of diseases associated with muscle wasting. J. Cell. Physiol. 232: 650-664, 2017. © 2016 The Authors. Journal of Cellular Physiology published by Wiley Periodicals, Inc.

Circadian Rhythms and Hormonal Homeostasis: Pathophysiological Implications

Over recent years, a deeper comprehension of the molecular mechanisms that control biological clocks and circadian rhythms has been achieved. In fact, many studies have contributed to unravelling the importance of the molecular clock for the regulation of our physiology, including hormonal and metabolic homeostasis. Here we will review the structure, organisation and molecular machinery that make our circadian clock work, and its relevance for the proper functioning of physiological processes. We will also describe the interconnections between circadian rhythms and endocrine homeostasis, as well as the underlying consequences that circadian dysregulations might have in the development of several pathologic affections. Finally, we will discuss how a better knowledge of such relationships might prove helpful in designing new therapeutic approaches for endocrine and metabolic diseases.

Glucocorticoids increase skeletal muscle NF-κB inducing kinase (NIK): links to muscle atrophy

Glucocorticoids (GC) are a frontline therapy for numerous acute and chronic diseases because of their demonstrated efficacy at reducing systemic inflammation. An unintended side effect of GC therapy is the stimulation of skeletal muscle atrophy. Pathophysiological mechanisms responsible for GC-induced skeletal muscle atrophy have been extensively investigated, and the ability to treat patients with GC without unintended muscle atrophy has yet to be realized. We have reported that a single, standard-of-care dose of Methylprednisolone increases in vivo expression of NF-κB-inducing kinase (NIK), an important upstream regulatory kinase controlling NF-κB activation, along with other key muscle catabolic regulators such as Atrogin-1 and MuRF1 that induce skeletal muscle proteolysis. Here, we provide experimental evidence that overexpressing NIK by intramuscular injection of recombinant human NIK via adenoviral vector in mouse tibialis anterior muscle induces a 30% decrease in the average fiber cross-sectional area that is associated with increases in mRNA expression of skeletal muscle atrophy biomarkers MuRF1, Atrogin-1, myostatin and Gadd45. A single injection of GC induced NIK mRNA and protein within 2 h, with the increased NIK localized to nuclear and sarcolemmal locations within muscle fibers. Daily GC injections induced skeletal muscle fore limb weakness as early as 3 days with similar atrophy of muscle fibers as observed with NIK overexpression. NIK overexpression in primary human skeletal muscle myotubes increased skeletal muscle atrophy biomarkers, while NIK knockdown significantly attenuated GC-induced increases in NIK and Atrogin-1. These results suggest that NIK may be a novel, previously unrecognized mediator of GC-induced skeletal muscle atrophy.

Urinary glucocorticoid metabolites: biomarkers to classify adrenal incidentalomas?

OBJECTIVE

Total urinary cortisol metabolites represent cortisol production and metabolism. We hypothesized that to assay metabolites could add some information to the one provided by a sole cortisol assay.

DESIGN AND PATIENTS

We set up an inexpensive multiplex mass spectrometry assay to quantify cortisol metabolites. We investigated 43 patients with benign secreting (AT+) or silent (AT-) adrenal tumours compared to 48 lean (Nl) or 143 obese (Ob) subjects, and to 26 patients with a Cushing's disease (CD). The initial investigation included immunoreactive quantification of urinary free cortisol (UFC).

RESULTS

Cortisol metabolites were overexcreted in CD but not in Ob subjects. Nl and Ob were thus pooled in a control population (Ctl). Cortisol, tetrahydrocortisol (THF) and tetrahydrocortisone (THE) excretions were significantly increased in AT compared to Ctl subjects, whereas immunoreactive UFC was similar. A logistic regression retaining cortisol, THF, and α- and β-cortolone as significant analytes allowed the construction of a receiver-operating characteristics (ROC) curve significantly better than the curve generated by cortisol alone (area under the curve (AUC) 0·927 vs 0·729, respectively; P < 0·0001). More importantly, although there was no significant difference between Ctl vs AT- subjects for cortisol metabolites, a logistic regression retaining cortisol, allo-THF, and α- and β-cortolone as significant analytes generated a ROC curve performing significantly better than cortisol alone (AUC 0·910 vs 0·635, respectively; P < 0·0001).

CONCLUSION

Cortisol metabolite excretion is modified in AT, including AT-, patients even without modification of UFC. Clinical usefulness of these biomarkers has to be investigated in prospective studies following up patients with AT.

Determination of nighttime salivary cortisol during pregnancy: comparison with values in non-pregnancy and Cushing's disease

PURPOSE

Nighttime salivary cortisol (NSC) has been proposed for the diagnosis of Cushing's syndrome during pregnancy. However, reference values for NCS in pregnant women have not been adequately determined. The aim of this study was to determine the reference values of NSC in the three gestational trimesters in order to help distinguish physiological from pathological hypercortisolism during pregnancy.

METHODS

This prospective and retrospective study evaluated 85 pregnant women in whom samples were collected in the first, second and/or third gestational trimester (pregnancy group), 33 non-pregnant women (control group), and 25 non-pregnant women with Cushing's disease (CD group). NSC was measured by enzyme-linked immunosorbent assay.

RESULTS

NSC increased progressively during pregnancy, reaching maximum levels on the third trimester (median 2.1-fold increase compared with controls, p < 0.001). Reference values for NSC were determined and the upper limits on each gestational trimester were: first trimester 0.25 µg/dL (6.9 nmol/L), second trimester 0.26 µg/dL (7.2 nmol/L), and third trimester 0.33 µg/dL (9.1 nmol/L). Cutoff values that separated the CD group from the three trimesters in the pregnancy groups were, respectively, 0.255 µg/dL (7.0 nmol/L), 0.260 µg/dL (7.2 nmol/L), and 0.285 µg/dL (7.9 nmol/L). Comparison of NSC cutoff values in pregnant women with CD patients showed high sensitivity and specificity in all three trimesters.

CONCLUSIONS

We established cutoff values for determination of NSC which can be useful for pregnant women with a diagnostic suspicion of CD.

Circadian rhythms in glucose and lipid metabolism in nocturnal and diurnal mammals

Most aspects of energy metabolism display clear variations during day and night. This daily rhythmicity of metabolic functions, including hormone release, is governed by a circadian system that consists of the master clock in the suprachiasmatic nuclei of the hypothalamus (SCN) and many secondary clocks in the brain and peripheral organs. The SCN control peripheral timing via the autonomic and neuroendocrine system, as well as via behavioral outputs. The sleep-wake cycle, the feeding/fasting rhythm and most hormonal rhythms, including that of leptin, ghrelin and glucocorticoids, usually show an opposite phase (relative to the light-dark cycle) in diurnal and nocturnal species. By contrast, the SCN clock is most active at the same astronomical times in these two categories of mammals. Moreover, in both species, pineal melatonin is secreted only at night. In this review we describe the current knowledge on the regulation of glucose and lipid metabolism by central and peripheral clock mechanisms. Most experimental knowledge comes from studies in nocturnal laboratory rodents. Nevertheless, we will also mention some relevant findings in diurnal mammals, including humans. It will become clear that as a consequence of the tight connections between the circadian clock system and energy metabolism, circadian clock impairments (e.g., mutations or knock-out of clock genes) and circadian clock misalignments (such as during shift work and chronic jet-lag) have an adverse effect on energy metabolism, that may trigger or enhancing obese and diabetic symptoms.

Early endocrine alterations reflect prolonged stress and relate to 1-year functional outcome in patients with severe brain injury

OBJECTIVE

Severe brain injury may increase the risk of developing acute and chronic hypopituitarism. Pituitary hormone alterations developed in the early recovery phase after brain injury may have implications for long-term functional recovery. The objective of the present study was to assess the pattern and prevalence of pituitary hormone alterations 3 months after a severe brain injury with relation to functional outcome at a 1-year follow-up.

DESIGN

Prospective study at a tertiary university referral centre.

METHODS

A total of 163 patients admitted to neurorehabilitation after severe traumatic brain injury (TBI, n=111) or non-TBI (n=52) were included. The main outcome measures were endocrine alterations 3.3 months (median) after the brain injury and their relationship to the functioning and ability of the patients at a 1-year follow-up, as measured by the Functional Independence Measure and the Glasgow Outcome Scale-Extended.

RESULTS

Three months after the injury, elevated stress hormones (i.e. 30 min stimulated cortisol, prolactin and/or IGF1) and/or suppressed gonadal or thyroid hormones were recorded in 68 and 32% of the patients respectively. At 1 year after the injury, lower functioning level (Functional Independence Measure) and lower capability of performing normal life activities (Glasgow Outcome Scale-Extended) were related to both the elevated stress hormones (P≤0.01) and the reduced gonadal and/or thyroid hormones (P≤0.01) measured at 3 months.

CONCLUSION

The present study suggests that brain injury-related endocrine alterations that mimic secondary hypogonadism and hypothyroidism and that occur with elevated stress hormones most probably reflect a prolonged stress response 2-5 months after severe brain injury, rather than pituitary insufficiency per se. These endocrine alterations thus seem to reflect a more severe disease state and relate to 1-year functional outcome.

Circadian systems biology in Metazoa

Systems biology, which can be defined as integrative biology, comprises multistage processes that can be used to understand components of complex biological systems of living organisms and provides hierarchical information to decoding life. Using systems biology approaches such as genomics, transcriptomics and proteomics, it is now possible to delineate more complicated interactions between circadian control systems and diseases. The circadian rhythm is a multiscale phenomenon existing within the body that influences numerous physiological activities such as changes in gene expression, protein turnover, metabolism and human behavior. In this review, we describe the relationships between the circadian control system and its related genes or proteins, and circadian rhythm disorders in systems biology studies. To maintain and modulate circadian oscillation, cells possess elaborative feedback loops composed of circadian core proteins that regulate the expression of other genes through their transcriptional activities. The disruption of these rhythms has been reported to be associated with diseases such as arrhythmia, obesity, insulin resistance, carcinogenesis and disruptions in natural oscillations in the control of cell growth. This review demonstrates that lifestyle is considered as a fundamental factor that modifies circadian rhythm, and the development of dysfunctions and diseases could be regulated by an underlying expression network with multiple circadian-associated signals.

β-Hydroxy β-methylbutyrate improves dexamethasone-induced muscle atrophy by modulating the muscle degradation pathway in SD rat

Skeletal muscle atrophy results from various conditions including high levels of glucocorticoids, and β-hydroxy β-methylbutyrate (HMB; a metabolite of leucine) is a potent therapeutical supplement used to treat various muscle disorders. Recent studies have demonstrated that HMB inhibits dexamethasone-induced atrophy in cultured myotubes, but its effect on dexamethasone-induced muscle atrophy has not been determined in vivo. In the present study, we investigated the effect of HMB on dexamethasone-induced muscle atrophy in rats. Treatment with dexamethasone weakened grip strengths and increased muscle damage as determined by increased serum creatine kinase levels and by histological analysis. Dexamethasone treatment also reduced both soleus and gastrocnemius muscle masses. However, HMB supplementation significantly prevented reductions in grip strengths, reduced muscle damage, and prevented muscle mass and protein concentration decrease in soleus muscle. Biochemical analysis demonstrated that dexamethasone markedly increased levels of MuRF1 protein, which causes the ubiquitination and degradation of MyHC. Indeed, dexamethasone treatment decreased MyHC protein expression and increased the ubiquitinated-MyHC to MyHC ratio. However, HMB supplementation caused the down-regulations of MuRF1 protein and of ubiquitinated-MyHC. Furthermore, additional experiments provided evidence that HMB supplementation inhibited the nuclear translocation of FOXO1 induced by dexamethasone, and showed increased MyoD expression in the nuclear fractions of soleus muscles. These findings suggest that HMB supplementation attenuates dexamethasone-induced muscle wasting by regulating FOXO1 transcription factor and subsequent MuRF1 expression. Accordingly, our results suggest that HMB supplementation could be used to prevent steroid myopathy.

Network identification of hormonal regulation

Relations among hormone serum concentrations are complex and depend on various factors, including gender, age, body mass index, diurnal rhythms and secretion stochastics. Therefore, endocrine deviations from healthy homeostasis are not easily detected or understood. A generic method is presented for detecting regulatory relations between hormones. This is demonstrated with a cohort of obese women, who underwent blood sampling at 10 minute intervals for 24-hours. The cohort was treated with bromocriptine in an attempt to clarify how hormone relations change by treatment. The detected regulatory relations are summarized in a network graph and treatment-induced changes in the relations are determined. The proposed method identifies many relations, including well-known ones. Ultimately, the method provides ways to improve the description and understanding of normal hormonal relations and deviations caused by disease or treatment.

An N-ethyl-N-nitrosourea induced corticotropin-releasing hormone promoter mutation provides a mouse model for endogenous glucocorticoid excess

Cushing's syndrome, which is characterized by excessive circulating glucocorticoid concentrations, may be due to ACTH-dependent or -independent causes that include anterior pituitary and adrenal cortical tumors, respectively. ACTH secretion is stimulated by CRH, and we report a mouse model for Cushing's syndrome due to an N-ethyl-N-nitrosourea (ENU) induced Crh mutation at -120 bp of the promoter region, which significantly increased luciferase reporter activity and was thus a gain-of-function mutation. Crh(-120/+) mice, when compared with wild-type littermates, had obesity, muscle wasting, thin skin, hair loss, and elevated plasma and urinary concentrations of corticosterone. In addition, Crh(-120/+) mice had hyperglycemia, hyperfructosaminemia, hyperinsulinemia, hypercholesterolemia, hypertriglyceridemia, and hyperleptinemia but normal adiponectin. Crh(-120/+) mice also had low bone mineral density, hypercalcemia, hypercalciuria, and decreased concentrations of plasma PTH and osteocalcin. Bone histomorphometry revealed Crh(-120/+) mice to have significant reductions in mineralizing surface area, mineral apposition, bone formation rates, osteoblast number, and the percentage of corticoendosteal bone covered by osteoblasts, which was accompanied by an increase in adipocytes in the bone marrow. Thus, a mouse model for Cushing's syndrome has been established, and this will help in further elucidating the pathophysiological effects of glucocorticoid excess and in evaluating treatments for corticosteroid-induced osteoporosis.

Interactions between endocrine and circadian systems

In most species, endogenous circadian clocks regulate 24-h rhythms of behavior and physiology. Clock disruption has been associated with decreased cognitive performance and increased propensity to develop obesity, diabetes, and cancer. Many hormonal factors show robust diurnal secretion rhythms, some of which are involved in mediating clock output from the brain to peripheral tissues. In this review, we describe the mechanisms of clock-hormone interaction in mammals, the contribution of different tissue oscillators to hormonal regulation, and how changes in circadian timing impinge on endocrine signalling and downstream processes. We further summarize recent findings suggesting that hormonal signals may feed back on circadian regulation and how this crosstalk interferes with physiological and metabolic homeostasis.

β-Hydroxy-β-methylbutyrate (HMB) prevents dexamethasone-induced myotube atrophy

High levels of glucocorticoids result in muscle wasting and weakness. β-hydroxy-β-methylbutyrate (HMB) attenuates the loss of muscle mass in various catabolic conditions but the influence of HMB on glucocorticoid-induced muscle atrophy is not known. We tested the hypothesis that HMB prevents dexamethasone-induced atrophy in cultured myotubes. Treatment of cultured L6 myotubes with dexamethasone resulted in increased protein degradation and expression of atrogin-1 and MuRF1, decreased protein synthesis and reduced myotube size. All of these effects of dexamethasone were attenuated by HMB. Additional experiments provided evidence that the inhibitory effects of HMB on dexamethasone-induced increase in protein degradation and decrease in protein synthesis were regulated by p38/MAPK- and PI3K/Akt-dependent cell signaling, respectively. The present results suggest that glucocorticoid-induced muscle wasting can be prevented by HMB.

Cushing's syndrome: diagnosis and surveillance using salivary cortisol

This short review summarizes the use of late-night salivary cortisol measurement in the diagnosis of Cushing's syndrome, in the evaluation of patients with adrenal incidentalomas, and in monitoring of post-operative patients, with a focus on the different assay methodologies currently in common use. The focus is on recent studies identified by literature searches using Ovid Medline and Google Scholar as well as analysis of several recent review articles on the topic. Measurement of late night salivary cortisol (LNSC) has an excellent sensitivity and specificity for the diagnosis of Cushing's syndrome regardless of the assay methodology used. Immunoassays have the advantage of simplicity, low cost, and small sample volume requirement, while liquid chromatography-tandem mass spectrometry has the advantage of a high specificity for cortisol and the ability to measure cortisone. The overnight dexamethasone suppression test appears to be superior to LNSC measurement in the evaluation of patients with adrenal incidentalomas. LNSC measurement is an excellent approach to monitor post-operative Cushing's disease patients for surgical failure or recurrence. Salivary cortisol is most useful as the initial test when Cushing's syndrome is suspected and for periodic patient monitoring after pituitary surgery for Cushing's disease.

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.