Bone mineral density at diagnosis and following successful treatment of pediatric Cushing's disease

Cushing's disease and bone

Bone impairment associated with Cushing's disease (CD) is a complex disorder, mainly involving deterioration of bone quality and resulting in an increased fracture rate, often despite normal bone mineral density. Bone complications are common in patients with CD at the time of diagnosis but may persist even after successful treatment. There is currently no agreement on the optimal diagnostic methods, thresholds for anti-osteoporotic therapy and its timing in CD. In this review, we summarize the current data on the pathophysiology, diagnostic approach and management of bone complications in CD.

Paediatric Cushing's disease: long-term outcome and predictors of recurrence

Paediatric Cushing's disease (CD) is characterized by excess ACTH secretion from a pituitary adenoma, leading to hypercortisolism. It has approximately 5% of the incidence of adult CD and is a rare disorder in the paediatric age range. The four most specific presenting features of hypercortisolism are: change in facial appearance, weight gain, decreased linear growth and virilisation shown by advanced pubic hair for the stage of breast development or testicular volume. The main diagnostic priority is the demonstration of hypercortisolism followed by distinction between its ACTH-dependent and ACTH-independent origin, thus leading to identification of aetiology. All treatment options aim to resolve or control hypercortisolism. Consensus favours transsphenoidal (TSS) pituitary surgery with selective removal of the corticotroph adenoma. TSS in children with CD is now well established and induces remission in 70-100% of cases. External pituitary radiotherapy and bilateral adrenalectomy are second-line therapeutic approaches in subjects not responding to TSS. Long-term medical treatment is less frequently adopted. Recurrence in paediatric CD cases is low with factors predicting relapse being higher post-TSS cortisol and ACTH levels and rapid recovery of the hypothalamic-pituitary-adrenal axis after TSS. In summary, complete excision of the microadenoma with histological and biochemical evidence for this, predicts a low rate of recurrence of CD. Due to the need for rapid diagnosis and management to avoid the burden of prolonged exposure to hypercortisolism, tertiary university centres comprising both paediatric and adult endocrinology specialists together with experienced pituitary surgery and, eventually, radiotherapy units are recommended for referral of these patients.

Pituitary Diseases and Bone

Neuroendocrinology of bone is a new area of research based on the evidence that pituitary hormones may directly modulate bone remodeling and metabolism. Skeletal fragility associated with high risk of fractures is a common complication of several pituitary diseases such as hypopituitarism, Cushing disease, acromegaly, and hyperprolactinemia. As in other forms of secondary osteoporosis, pituitary diseases generally affect bone quality more than bone quantity, and fractures may occur even in the presence of normal or low-normal bone mineral density as measured by dual-energy X-ray absorptiometry, making difficult the prediction of fractures in these clinical settings. Treatment of pituitary hormone excess and deficiency generally improves skeletal health, although some patients remain at high risk of fractures, and treatment with bone-active drugs may become mandatory. The aim of this review is to discuss the physiological, pathophysiological, and clinical insights of bone involvement in pituitary diseases.

Chronic Corticosterone Treatment During Adolescence Has Significant Effects on Metabolism and Skeletal Development in Male C57BL6/N Mice

Glucocorticoids are potent modulators of metabolic and behavioral function. Their role as mediators in the "stress response" is well known, but arguably their primary physiological function is in the regulation of cellular and organismal metabolism. Disruption of normal glucocorticoid function is linked to metabolic disease, such as Cushing syndrome. Glucocorticoids are also elevated in many forms of obesity, suggesting that there are bidirectional effects of these potent hormones on metabolism and metabolic function. Adolescence is a time of rapid physical growth, and disruptions during this critical time likely have important implications for adult function. The hypothalamic-pituitary-adrenal axis continues to mature during this period, as do tissues that respond to glucocorticoids. In this work, we investigate how chronic noninvasive exposure to corticosterone affects metabolic outcomes (body weight, body composition, insulin, and glucose homeostasis), as well as changes in bone density in both adult and adolescent male mice. Specifically, we report a different pattern of metabolic effects in adolescent mice compared with adults, as well as an altered trajectory of recovery in adolescents and adults. Together, these data indicate the profound influence that adolescent development has on the metabolic outcomes of chronic corticosterone exposure, and describe a tractable model for understanding the short- and long-term impacts of hypercortisolemic states on physiological and neurobehavioral functions.

Glucocorticoid-induced osteoporosis: pathophysiological role of GH/IGF-I and PTH/VITAMIN D axes, treatment options and guidelines

Glucocorticoid-induced osteoporosis is the most frequent form of secondary osteoporosis caused by chronic exposure to glucocorticoid excess. Pathogenesis of glucocorticoid-induced osteoporosis is multifactorial including direct effects of glucocorticoids on bone cells and indirect effects of glucocorticoids on several neuroendocrine and metabolic pathways. Fragility fractures occur early in glucocorticoid-induced osteoporosis and anti-osteoporotic drugs along with calcium and vitamin D should be started soon after exposure to glucocorticoid excess. This paper summarizes some of the main topics discussed during the 9th Glucocorticoid-Induced Osteoporosis Meeting (Rome, April 2016) with a specific focus on the role of growth hormone/insulin-like growth factor-1 and parathyroid hormone/vitamin D axes in the pathogenesis of glucocorticoid-induced osteoporosis and the controversial aspects concerning therapeutic approach to skeletal fragility in this clinical setting.

MANAGEMENT OF ENDOCRINE DISEASE: Paediatric Cushing's disease

Cushing's disease (CD) is the commonest form of ACTH-dependent Cushing's syndrome and is a rare clinical diagnosis in paediatric and adolescent patients. CD is caused by an ACTH-secreting pituitary corticotroph adenoma and is associated with significant morbidity in children; therefore, early diagnosis and treatment are critical for optimal therapeutic outcome. This review highlights the key clinical and biochemical features of paediatric CD and appraises current practices in diagnosis and management. A close liaison with adult endocrinology colleagues, particularly, for interpretation of investigations and definition of therapeutic strategy is strongly advised.

Quality of life and other outcomes in children treated for Cushing syndrome

CONTEXT

Cushing syndrome (CS) in children is associated with residual impairment in measures of health-related quality of life, even after successful resolution of hypercortisolemia, highlighting the need for early identification of morbidities and improvements in long-term management of these patients.

EVIDENCE ACQUISITION AND SYNTHESIS

A PubMed, Scopus, and Web of Science search of articles from 1900 onward identified available studies related to quality of life and complications of pediatric CS as well as important historical articles. This review summarizes studies through November 2012 and highlights recent developments.

CONCLUSIONS

A review of the literature identifies significant morbidities associated with CS of pediatric onset, which must not be treated in isolation. CS affects children and adolescents in many ways that are different than adults. Post-treatment challenges for the child or adolescent treated for CS include: optimize growth and pubertal development, normalize body composition, and promote psychological health and cognitive maturation. All these factors impact health-related quality of life, which is an important outcome measure to assess the burden of disease as well as the effect of treatment. Future research efforts are needed to improve management of the physical, psychological, and emotional aspects of this disease in order to diminish the residual impairments experienced by the pediatric CS patient population.

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.

Effects of Cushing disease on bone mineral density in a pediatric population

OBJECTIVE

To evaluate bone mineral density (BMD) in children with Cushing disease before and after transphenoidal surgery (TSS).

STUDY DESIGN

Hologic dual-energy x-ray absorptiometry (DXA) scans of 35 children with Cushing disease were analyzed retrospectively. Sixteen of the 35 patients had follow-up DXA scans performed 13 to 18 months after TSS. BMD and bone mineral apparent density (BMAD) for lumbar spine (LS) L1 to L4 and femoral neck (FN) were calculated.

RESULTS

Preoperatively, 38% and 23% of patients had osteopenia of the LS and FN, respectively. Both BMD and BMAD Z-scores of the LS were worse than those for the FN (-1.60 +/- 1.37 versus -1.04 +/- 1.19, P = .003), and (-1.90 +/- 1.49 versus -0.06 +/- 1.90, P < .001); postoperative improvement in BMD and BMAD were more pronounced in LS than in the FN (0.84 +/- 0.88 versus 0.15 +/- 0.62, P<.001; and 0.73 +/- 1.13 versus -0.26 +/- 1.21, P = .015). Pubertal stage, cortisol levels, and length of disease had no effect on BMD.

CONCLUSIONS

In children with Cushing disease, vertebral BMD was more severely affected than femoral BMD and this effect was independent of degree or duration of hypercortisolism. BMD for the LS improved significantly after TSS; osteopenia in this group may be reversible.

Bone turnover in patients with endogenous Cushing's syndrome before and after successful treatment

We investigated bone turnover and its restoration in a large number of patients in the active phase and after cure of endogenous Cushing's syndrome. Furthermore, the usefulness of serum osteocalcin and collagen breakdown products as potential markers of active Cushing's syndrome was also evaluated.

INTRODUCTION

Suppressed bone formation is one of the most characteristic features of Cushing's syndrome (CS). Despite numerous previous reports, many aspects of the disturbed bone metabolism of these patients are unexplored. In this study, we investigated the time course of bone marker changes after the cure of CS as well as correlations between bone markers and serum cortisol concentrations.

METHODS

Eighty-seven patients with CS were studied. Patients were followed up to 48 months after surgical cure. Serum osteocalcin (OC) and collagen breakdown products (CTX) were measured with immunochemiluminescence method and compared to the results of 161 healthy controls.

RESULTS

OC showed a negative, while CTX displayed a positive correlation with serum cortisol. Patients with diabetes mellitus and myopathy had significantly lower serum OC levels compared to those without these complications. The area under the curve of OC obtained by receiver-operating characteristics analysis for the discrimination of patients with CS from healthy controls was 0.9227. Postoperative OC increased rapidly from the first few days or weeks reaching its maximum at the sixth month and remained stable after the 24th postoperative month.

CONCLUSIONS

Our study demonstrated significant correlations between serum cortisol and both bone formation and resorption markers in the active phase of CS. We propose that OC may serve as a sensitive biologic marker of glucocorticoid activity in endogenous CS during its active phase and it may reflect the clinical cure of the disease.

[Cushing's syndrome: special issues]

The present article reviews: Corticotrophin (ACTH) independent bilateral macronodular adrenal hyperplasia, which is characterized by aberrant adrenal receptors due to either ectopic expression or to overexpression (eutopic expression). Micronodular adrenal hyperplasia, which provokes small pigmented nodules in the adrenal gland with atrophy of the internodal tissue. These nodules may not be visible on imaging tests. The term subclinical Cushing's syndrome, coined in 1981, should be used in patients with clinically non-functioning adrenal adenomas but who show autonomous cortisol production that is insufficient to generate overt Cushing's syndrome. This entity must be distinguished from preclinical Cushing's syndrome, given that the subclinical form does not necessarily herald the development of symptoms of hypercortisolism. Cushing's syndrome is uncommon in children and adolescents. Regarding the general incidence of the disease, only 10% of cases are diagnosed in this age group. The most common cause of endogenous Cushing's disease in children older than 7 years is ACTH-dependent Cushing's disease (85%). The association of Cushing's syndrome and pregnancy is highly uncommon, since hypercortisolism usually causes amenorrhea, oligomenorrhea and infertility due to inhibition of gonadotropin secretion. One hundred thirty-six pregnancies have been described in 122 women, with a gestational age at diagnosis of 18.4+/-1 weeks.

Skeletal differences in bone mineral area and content before and after cure of endogenous Cushing's syndrome

We examined bone densitometric data in a four-year follow-up period before and after the cure of CS. Plasma cortisol concentrations were similar, but the duration of estimated glucocorticoid excess was longer in patients with prevalent bone fractures compared to those without fractures. After therapy of CS, bone area, BMC and BMD increased significantly at the LS and femur during follow-up, but they decreased at the forearm, suggesting redistribution of bone minerals from the peripheral to the axial skeleton.

INTRODUCTION

Only a few studies report the changes in bone mineral density (BMD) after the cure of Cushing's syndrome (CS).

METHODS

Forty-one patients with Cushing's disease, 21 patients with adrenal CS and 6 patients with ectopic CS were prospectively enrolled. BMD, bone mineral content (BMC) and bone area were measured by DXA.

RESULTS

No significant correlations were found between serum cortisol concentrations and baseline bone densitometric data. After successful therapy of CS, bone area and BMD increased significantly at the lumbar spine (LS) and femur during follow-up, but they decreased at the forearm. The progressive increase in BMC at the LS had a significant negative correlation with the change of the BMC of radius in the first and second follow-up years. The change in the body mass index was an independent predictor for changes in BMC both at the LS and at the forearm at the second year of remission.

CONCLUSIONS

The regional differences and the time-dependent changes of BMC suggest that the source of marked increase in axial BMC after the cure of CS is, at least partly, due to the redistribution of bone minerals from the peripheral to the axial skeleton.

Pediatric Cushing's syndrome: clinical features, diagnosis, and treatment

Cushing's syndrome (CS) results from prolonged exposure to supraphysiological levels of circulating glucocorticoids, endogenously or exogenously derived. Although rare in childhood, CS remains a difficult condition to diagnose and treat. A multidisciplinary approach and close collaboration with adult colleagues is adopted at most large centres that manage pediatric CS patients. Although pediatric protocols are derived from adult data, significant differences exist between adult and childhood CS. Furthermore, long term outcome parameters including final height, bone mineral density, reproductive function, body composition and psychological health pose challenges for pediatric care. This article will aim to provide an overall view of pediatric CS highlighting some of the differences between adult and pediatric CS.

Paediatric Cushing's syndrome: epidemiology, investigation and therapeutic advances

Cushing's syndrome (CS), which is caused by excessive circulating glucocorticoid concentrations, is rare in the paediatric age range but presents a diagnostic and therapeutic challenge. Most paediatric endocrinologists have limited experience of managing children or adolescents with CS and thus benefit from close consultation with colleagues who treat adult patients. A protocol for investigation is required that broadly follows the model for adult patients. Here, the epidemiology and diagnosis of different causes of CS are discussed according to typical age of presentation. Treatment strategies for adrenocorticotrophic hormone (ACTH)-independent and ACTH-dependent CS are described and critically appraised. The management of paediatric CS patients after cure also presents challenges for optimizing growth, bone health, reproduction and body composition from childhood into and during adult life.

Factors influencing skeletal maturation at diagnosis of paediatric Cushing's disease

BACKGROUND/AIMS

Growth retardation is a recognised complication of paediatric Cushing's disease (CD), but there are few published data on skeletal maturation at diagnosis. We assessed factors contributing to skeletal maturation in patients with paediatric CD.

PATIENTS/METHODS

17 patients, 12 males, 5 females (median age 12.1 years, range 5.8-17.4) were studied. The bone age (BA) of each child was determined by a single observer using the TW3 RUS method. BA delay, i.e. the difference between chronological age (CA) and BA, was compared with clinical and biochemical variables.

RESULTS

BA delay was present in 15/17 patients (mean delay 2.0 years, range -0.5 to 4.1 years) and correlated negatively with height SDS (r = -0.70, p < 0.01) and positively with duration of symptoms (r = 0.48, p = 0.05) and CA (r = 0.48, p = 0.05). No relationships were found with midnight cortisol, ACTH, DHEA-S or cortisol suppression during the low-dose dexamethasone suppression test.

CONCLUSIONS

BA in most children with CD was delayed and related to length of symptoms and height SDS at diagnosis. Early diagnosis will reduce delay in skeletal maturation and thus contribute to optimal catch-up growth.

Effects of child- and adolescent-onset endogenous Cushing syndrome on bone mass, body composition, and growth: a 7-year prospective study into young adulthood

The long-term effects on bone and fat mass in children with endogenous CS are unknown. In 14 children followed for 3-7 years into young adulthood after cure of CS, whereas bone mass largely recovered, persisting increases in total body and visceral fat suggests an increase risk of the metabolic syndrome.

INTRODUCTION

Endogenous Cushing syndrome (CS) is associated with decreased bone mass and increased central fat mass. Whereas bone mass seems to improve after successful treatment, little is known about whether central fat persists.

MATERIALS AND METHODS

This was a prospective study of 14 children (10 girls and 4 boys) and adolescents with CS who were successfully treated and remained eucortisolemic. Growth, puberty, bone mass, and body composition were evaluated at baseline and during regular follow-up for 3 years and in seven children for a further 4 years of remission to assess final adult height (FH), BMI, bone mass, and body composition.

RESULTS

CS compromised growth, leading to about a -0.8 SD loss of FH and 0.9 SD increase in weight and BMI. BMD apparent density (BMAD) SD Score (SDS) at the lumbar spine (LS) at diagnosis were -1.8 and -1.25, respectively, and after 3 years of follow-up approached the mean with no further increase apparent up to 7 years of follow-up. Whereas hip BMD SDS increased from -1.3 at diagnosis to -0.40 at 3 years and 0 at 7 years of follow-up, femoral neck BMAD remained at or around 0 SDS at diagnosis and during follow-up. BMI was >25 kg/m(2) in five of seven adult subjects, most of whom were women. Total body fat and the ratio of visceral to subcutaneous was abnormally high in the majority of these subjects, whereas LS volumetric BMD was -0.7 SDS.

CONCLUSIONS

Despite remission of CS, children and adolescents have significant alterations in body composition that result in a small but significant decrease in bone mass and increase in visceral adiposity. Although bone mass largely recovers after endogenous CS, changes in total and visceral fat suggest these subjects are at increased risk of the metabolic syndrome. Therefore, long-term monitoring of body fat and bone mass is mandatory after treatment of CS.

Diagnosis and treatment of pediatric Cushing's disease

Cushing's disease (CD) is rare in the pediatric age range, but may present a diagnostic and therapeutic challenge. Most pediatric endocrinologists have limited experience managing children or adolescents with CD and thus benefit from close consultation with adult colleagues. A diagnostic protocol for investigation is required which broadly follows the model for adult patients. Treatment strategies for CD are described and critically appraised. The management of pediatric CD patients after cure also presents challenges for optimizing growth, bone health, reproduction and body composition from childhood into and during adult life.

Cushing's syndrome

Cushing's syndrome results from lengthy and inappropriate exposure to excessive glucocorticoids. Untreated, it has significant morbidity and mortality. The syndrome remains a challenge to diagnose and manage. Here, we review the current understanding of pathogenesis, clinical features, diagnostic, and differential diagnostic approaches. We provide diagnostic algorithms and recommendations for management.

Metabolic Bone Disease in Children

Metabolic bone disease in children includes many hereditary and acquired conditions of diverse etiology that lead to disturbed metabolism of the bone tissue. Some of these processes primarily affect bone; others are secondary to nutritional deficiencies, a variety of chronic disorders, and/or treatment with some drugs. Some of these disorders are rare, but some present public health concerns (for instance, rickets) that have been well known for many years but still persist. The most important clinical consequences of bone metabolic diseases in the pediatric population include reduced linear growth, bone deformations, and non-traumatic fractures leading to bone pain, deterioration of motor development and disability. In this article, we analyze primary and secondary osteoporosis, rickets, osteomalacia (nutritional and hereditary vitamin D-dependent, hypophosphatemic and that due to renal tubular abnormalities), renal osteodystrophy, sclerosing bony disorders, and some genetic bone diseases (hypophosphatasia, fibrous dysplasia, skeletal dysplasia, juvenile Paget disease, familial expansile osteolysis, and osteoporosis pseudoglioma syndrome). Early identification and treatment of potential risk factors is essential for skeletal health in adulthood. In most conditions it is necessary to ensure an appropriate diet, with calcium and vitamin D, and an adequate amount of physical activity as a means of prevention. In secondary bone diseases, treatment of the primary disorder is crucial. Most genetic disorders await prospective gene therapies, while bone marrow transplantation has been attempted in other disorders. At present, affected patients are treated symptomatically, frequently by interdisciplinary teams. The role of exercise and pharmacologic therapy with calcium, vitamin D, phosphate, bisphosphonates, calcitonin, sex hormones, growth hormone, and thiazides is discussed. The perspectives on future therapy with insulin-like growth factor-1, new analogs of vitamin D, strontium, osteoprotegerin, and calcimimetics are presented.