Persistent increase of osteoprotegerin levels after cortisol normalization in patients with Cushing's syndrome

Capillary microarchitectural changes in Cushing's syndrome

PURPOSE

Macrovascular alterations are prominent in Cushing's syndrome (CS). Microvascular abnormalities are yet to be established. This cross-sectional observational study aimed to evaluate microvascular changes in nailfold capillaries and their association with disease status and carotid intima-media thickness (CIMT) as a marker of atherosclerosis.

METHODS

A total of 70 patients with CS [46 (65.7%) ACTH-dependent pituitary adenoma and 24 (34.3%) adrenocortical adenomas] and 100 healthy controls were enrolled. The microvascular structure was evaluated using nailfold video-capillaroscopy (NVC).

RESULTS

The median number of capillaries was less [10 mm (IQR: 2, min-max:7-14) vs. 11 mm (IQR: 2, min-max:9-19) (p < 0.001)], the median limb diameter and capillary width were wider in the CS group than in the controls (p = 0.016 and p = 0.002, respectively). Microhemorrhages within limited areas were more frequent in the CS group than in the controls (p = 0.046). Observed capillary changes were similar among the patients with CS with remission or active disease. CIMT levels were higher in the CS group than in the controls and similar in subjects with active disease and remission. Univariate logistic regression analyses revealed that the number of capillaries and capillary widths were associated with body mass index (BMI), the presence of type 2 diabetes mellitus, HbA1c, and CIMT.

CONCLUSION

Morphologic alterations present similarly in nailfold capillaries in subjects with CS regardless of disease status, resembling changes in chronic atherosclerotic diseases. Microvascular changes in nailfold capillaries measured using NVC can be used as a marker in the assessment of cardiovascular risk in patients with CS.

Cushing's syndrome is associated with altered adipokine profile

INTRODUCTION

Adipokines are signaling molecules involved in the integration of metabolism. Changes in their concentrations were observed in obesity, metabolic syndrome, diabetes mellitus and cardiovascular diseases, as well as endocrine disorders. Cushing's syndrome is associated with metabolic dysregulation, but the significance of adipokines in this entity and related complications is largely unknown. The aim of our study was to determine the concentrations of adipokines: fetuin A, fatty acid binding protein 4 (FABP4) and retinol binding protein 4 (RBP4) in Cushing's syndrome and to assess their relation to established cardiovascular and diabetes risk markers.

METHODS

We examined 21 subjects with Cushing's syndrome and 24 healthy controls in a cross-sectional manner. Venous blood samples were analysed for adipokines, cortisol, adrenocorticotrophin, glucose, insulin, glycated haemoglobin (HbA1c), triglycerides, cholesterol fractions, thyrotropin and free thyroid hormones concentrations. Patients' body mass index (BMI) was evaluated, homeostatic model assessment-insulin resistance and Systematic Coronary Risk Evaluation (SCORE) were calculated.

RESULTS

We found that the concentration of fetuin A was lower, while FABP4 and RBP4 concentrations were higher in Cushing's syndrome compared to controls [156.4 ± 60.0 µg/ml vs 260.7 ± 49.6 µg/ml; 79.8 (35.2-156.1) ng/ml vs 27.9 (17.1-36.7) ng/ml and 34 (30-37.7) mg/l vs 25.8 (23.6-27.7) mg/l, respectively]. Fetuin A correlated inversely, while FABP4 and RBP4 positively, with the concentrations of urinary free cortisol and adrenocorticotrophin. Fetuin A was positively related to LDL-cholesterol, and negatively to SCORE and HbA1c. FABP4 was associated positively with BMI, HbA1c and triglycerides, while RBP4 correlated positively with triglycerides and systolic blood pressure.

CONCLUSIONS

Adipokines' concentrations change in hypercortisolism. Further research is needed to ascertain whether adipokines are involved in the development of metabolic complications accompanying Cushing's syndrome or secondarily reflect metabolic dysregulation.

Biochemical bone turnover markers in hormonal disorders in adults: a narrative review

BACKGROUND

Hormonal disorders are often associated with abnormal levels of bone turnover markers (BTMs). N-terminal propeptide of type I procollagen (PINP) and serum C-terminal cross-linking telopeptide of type I collagen (CTX-I) are the reference markers of bone formation and bone resorption, respectively.

METHODS

A comprehensive literature search within the MEDLINE and Web of Science databases was performed.

RESULTS

Acromegaly is associated with higher BTM levels, which decrease during the remission after treatment. Adult-onset growth hormone deficiency is often associated with decreased BTM levels. Growth hormone replacement therapy stimulates bone turnover and increases BTM levels. Hypothyroidism is characterized by general slowing of bone metabolism which is reflected by lower BTM levels. The replacement thyroid hormone therapy increases the bone turnover rate and BTM levels increase. Patients with thyroid cancer receive a suppressive dose of thyroid hormones and may have slightly elevated BTM levels. Patients with overt hyperthyroidism had higher BTM levels and anti-thyroid therapy induces a rapid decrease in the BTM levels. Patients with overt primary hyperparathyroidism have higher BTM levels, whereas those with asymptomatic and normocalcemic hyperparathyroidism usually have normal BTM levels. Hypoparathyroidism is characterized by slightly decreased BTM levels. Cushing's syndrome is characterized consistently by markedly decreased osteocalcin concentration, whereas data on other BTMs are discordant.

CONCLUSIONS

BTMs help us to better understand mechanisms of the impact of hormonal disorders and their treatment on bone metabolism. However, it is unknown whether BTMs may be used to monitor the effect of their treatments on bone in the clinical practice.

Evaluation of bone health in patients with adrenal tumors

PURPOSE OF REVIEW

Adrenal tumors occur in 5% of population with higher prevalence in elderly. Patients with adrenal tumors present with overt hormonal excess in up to 15% of cases, and mild autonomous cortisol secretion in 30-40% of cases. Overt Cushing syndrome, mild autonomous cortisol secretion, pheochromocytoma, and primary aldosteronism have been associated with higher cardiovascular morbidity and mortality. Increasing experimental and clinical evidence also suggests that adrenal hormone excess is detrimental to bone health. This review aims to discuss the effect of cortisol, aldosterone, and catecholamine excess on bone metabolism, secondary osteoporosis, and fragility fractures.

RECENT FINDINGS

Several studies have reported that patients with hormonally active adrenal tumors demonstrate increased prevalence of fragility fractures incongruous to bone density scan findings. The utility of dual absorptiometry X-ray (DXA) in diagnosing secondary osteoporosis is unclear in patients with cortisol, aldosterone, and catecholamine excess. Trabecular bone score and bone turn over markers could serve as potential diagnostic tools in assessment of severity of bone disease in patients with hormonally active adrenal tumors.

SUMMARY

Adrenalectomy is the mainstay of therapy in patients with overt hormone production. Appropriate case detection strategies to identify patients at risk of fragility fractures are needed in patients not treated with adrenalectomy, such as bilateral primary aldosteronism and mild autonomous cortisol secretion.

Mutiple Spontaneous Rib Fractures in Patient with Cushing's Syndrome

Glucocorticoid (GC) excess, including Cushing's syndrome, is a common cause of secondary osteoporosis. Thirty to fifty percent of Cushing's syndrome patients experience non-traumatic fractures, which is often the presenting manifestation of Cushing's syndrome. However, there have been rare cases of Cushing's syndrome diagnosed only based upon bone manifestations. We describe a case of Cushing's syndrome that was diagnosed in a 44-year-old woman who initially visited our hospital due to multiple non-traumatic rib fractures. She did not exhibit any other manifestations of Cushing's syndrome such as moon face, buffalo hump or abdominal striae. Initially, we evaluated her for bone metastases from a cancer of unknown origin, but there was no evidence of metastatic cancer. Instead, we found a left adrenal incidentaloma. As a result of the hormone study, she was diagnosed as having Cushing's syndrome. Interestingly, her bony manifestation of Cushing's syndrome, which was evident in the bone scan and bone mineral densitometry, completely recovered after a left adrenalectomy. Therefore, the possibility of Cushing's syndrome as a cause of secondary osteoporosis should be considered in young patients with non-traumatic multiple fractures, with or without any other typical features of Cushing's syndrome.

Impairment of Arterial Compliance in Cushing's Syndrome

Arterial stiffness may be useful for stratifying cardiovascular risk in individuals suffering from a number of pathologies, such as hypertension, diabetes, obesity, dyslipidaemia and coronary artery disease. Cushing's syndrome is underpinned by a complex metabolic syndrome, which is potentially implicated in the onset of blood vessel alterations and the increase in arterial wall stiffness. The aim of this paper was to perform a review about the most important studies conducted in order to evaluate the arterial distensibility profile of subjects affected by Cushing's syndrome. Increased arterial stiffness may persist even after successful cure of this disease. It is therefore of fundamental importance to identify the presence of early vascular alterations in these patients, in order to commence their treatment and thus attempt to prevent the subsequent onset of adverse cardiovascular events.

Serum extracellular secreted antagonists of the canonical Wnt/β-catenin signaling pathway in patients with Cushing's syndrome

Patients with endogenous hypercortisolism have higher sclerostin, but do not differ in Dickkopf 1 (Dkk1) or secreted frizzled-related protein 1 (SFRP1) levels as compared to healthy control.

INTRODUCTION

Endogenous Cushing's syndrome (CS), usually affecting young and otherwise healthy patients, is a good model to validate the effects of supraphysiological levels of glucocorticoids in humans. This study evaluates circulating levels of extracellular antagonists of the Wnt/β-catenin signaling pathway (sclerostin, Dkk1, SFRP1) in patients with CS versus healthy individuals.

METHODS

Forty patients with clinically and biochemically evident CS and 40 sex-, age-, and body mass index-matched healthy subjects provided fasting serum samples for sclerostin, SFRP1 and Dkk1, along with bone turnover markers.

RESULTS

Patients with CS had higher sclerostin levels (34.5 (30.3-37.1) pmol/L) versus healthy individuals (29.9 (24.3-36.8) pmol/L) (p = 0.032). Differences in sclerostin were due to the lack of lower sclerostin values rather than an increase in protein levels above the upper limits of the healthy control. The odds of sclerostin levels being higher than 30 pmol/L were greater in patients with CS as compared with the odds in healthy subjects (odds ratio = 3.81 95 % confidence interval 1.45-10.02) (p = 0.01). It coexisted with suppressed bone formation and unchanged bone resorption markers. Dkk1, SFRP1 did not differ from the control group.

CONCLUSIONS

Of all the tested proteins (sclerostin, Dkk1, SFRP1), only sclerostin showed a significant difference when contrasting CS with healthy subjects. Hypercortisolism might prevent the down-regulation of sclerostin. Targeting sclerostin seems to be a promising therapeutic approach to treating osteoporosis in patients with CS.

Glucocorticoid-induced osteoporosis: lessons from Cushing's syndrome

Glucocorticoid-induced osteoporosis (GIO) is the most frequent form of secondary bone disorders. Most of our knowledge on its pathogenesis and treatment has been obtained by investigating patients treated with exogenous glucocorticoids. This review will focus on the bone disorder in endogenous Cushing's syndrome, updating recent advances in its pathophysiology, diagnostic aspects and the various predictors which are important in determining bone mineral density (BMD) and fracture risk. We now know strong evidence that beside BMD, bone microarchitecture, one of the most important elements of bone quality, is a key factor in determining fracture risk. Recently, two new methods (spinal deformity index and trabecular bone score) have been shown to be useful markers of bone microarchitecture in GIO. Investigations of GIO in endogenous Cushing's syndrome have also contributed to our understanding on its natural history and reversibility. Relying on recently published guidelines for management of exogenous GIO, a short list of suggestions is provided regarding the optimal diagnostic and therapeutic approach to patients with endogenous GIO.

TXNIP is highly regulated in bone biopsies from patients with endogenous Cushing's syndrome and related to bone turnover

OBJECTIVE

Patients with endogenous Cushing's Syndrome (CS), as long-time treated patients with exogenous glucocorticoids (GCs), have severe systemic manifestations including secondary osteoporosis and low-energy fractures. The aim of the present study was to investigate the functional role of TXNIP in bone with focus on osteoblast (OB) differentiation and OB-mediated osteoclast activity and function in vitro.

DESIGN AND METHODS

Nine bone biopsies from CS before and after surgical treatment were screened for expressional candidate genes. Microarray analyses revealed that the gene encoding TXNIP ranked among the most upregulated genes. Subsequent in vitro and in vivo studies were performed.

RESULTS

We found that TXNIP gene in bone is downregulated in CS following surgical treatment. Furthermore, our in vivo data indicate novel associations between thioredoxin and TXNIP. Our in vitro studies showed that silencing TXNIP in OBs was followed by increased differentiation and expression and secretion of osteocalcin as well as enhanced activity of alkaline phosphatase. Moreover, treating osteoclasts with silenced TXNIP OB media showed an increased osteoclast activity.

CONCLUSIONS

TXNIP expression in bone is highly regulated during the treatment of active CS, and by GC in bone cells in vitro. Our data indicate that TXNIP may mediate some of the detrimental effects of GC on OB function as well as modulate OB-mediated osteoclastogenesis by regulating the OPG/RANKL ratio.

Advances in the epidemiology, pathogenesis, and management of Cushing's syndrome complications

Cushing's syndrome (CS) is a clinical condition resulting from chronic exposure to glucocorticoid excess. As a consequence, hypercortisolism contributes significantly to the early development of systemic disorders by direct and/or indirect effects. Complications such as obesity, hypertension, diabetes, dyslipidemia, and hypercoagulability cause premature atherosclerosis and increase cardiovascular mortality. Impairment of the skeletal system is a relevant cause of morbidity and disability in these patients especially due to the high prevalence of vertebral fractures. In addition, muscle weakness, emotional lability, depression, and impairment of quality of life are very common. Clinical management of these patients is complex and should be particularly careful in identifying global cardiovascular risks and aim at controlling all complications. Although the primary goal in the prevention and treatment of complications is the correction of hypercortisolism, treatment does not completely eliminate these comorbidities. Given that cardiovascular risk and fracture risk can persist after cure, early detection of each morbidity could prevent the development of irreversible damage. In this review we present the various complications of CS and their pathogenetic mechanisms. We also suggest the clinical management of these patients based on our extensive clinical experience and on the available literature.

Circulating TRAIL shows a significant post-partum decline associated to stressful conditions

Background

Since circulating levels of TNF-related apoptosis inducing ligand (TRAIL) may be important in the physiopathology of pregnancy, we tested the hypothesis that TRAIL levels change at delivery in response to stressful conditions.

Methods/Principal Findings

We conducted a longitudinal study in a cohort of 73 women examined at week 12, week 16, delivery and in the corresponding cord blood (CB). Serum TRAIL was assessed in relationship with maternal characteristics and to biochemical parameters. TRAIL did not vary between 12 (67.6±27.6 pg/ml, means±SD) and 16 (64.0±16.2 pg/ml) weeks' gestation, while displaying a significant decline after partum (49.3±26.4 pg/ml). Using a cut-off decline >20 pg/ml between week 12 and delivery, the subset of women with the higher decline of circulating TRAIL (41.7%) showed the following characteristics: i) nullipara, ii) higher age, iii) operational vaginal delivery or urgent CS, iv) did not receive analgesia during labor, v) induced labor. CB TRAIL was significantly higher (131.6±52 pg/ml) with respect to the corresponding maternal TRAIL, and the variables significantly associated with the first quartile of CB TRAIL (<90 pg/ml) were higher pre-pregnancy BMI, induction of labor and fetal distress. With respect to the biochemical parameters, maternal TRAIL at delivery showed an inverse correlation with C-reactive protein (CRP), total cortisol, glycemia and insulin at bivariate analysis, but only with CRP at multivariate analysis.

Conclusions

Stressful partum conditions and elevated CRP levels are associated with a decrease of circulating TRAIL.