Spontaneous, but not induced, puberty permits adequate bone mass acquisition in adolescent Turner syndrome patients

Clinical practice guidelines for the care of girls and women with Turner syndrome

Turner syndrome (TS) affects 50 per 100 000 females. TS affects multiple organs through all stages of life, necessitating multidisciplinary care. This guideline extends previous ones and includes important new advances, within diagnostics and genetics, estrogen treatment, fertility, co-morbidities, and neurocognition and neuropsychology. Exploratory meetings were held in 2021 in Europe and United States culminating with a consensus meeting in Aarhus, Denmark in June 2023. Prior to this, eight groups addressed important areas in TS care: (1) diagnosis and genetics, (2) growth, (3) puberty and estrogen treatment, (4) cardiovascular health, (5) transition, (6) fertility assessment, monitoring, and counselling, (7) health surveillance for comorbidities throughout the lifespan, and (8) neurocognition and its implications for mental health and well-being. Each group produced proposals for the present guidelines, which were meticulously discussed by the entire group. Four pertinent questions were submitted for formal GRADE (Grading of Recommendations, Assessment, Development and Evaluation) evaluation with systematic review of the literature. The guidelines project was initiated by the European Society for Endocrinology and the Pediatric Endocrine Society, in collaboration with members from the European Society for Pediatric Endocrinology, the European Society of Human Reproduction and Embryology, the European Reference Network on Rare Endocrine Conditions, the Society for Endocrinology, and the European Society of Cardiology, Japanese Society for Pediatric Endocrinology, Australia and New Zealand Society for Pediatric Endocrinology and Diabetes, Latin American Society for Pediatric Endocrinology, Arab Society for Pediatric Endocrinology and Diabetes, and the Asia Pacific Pediatric Endocrine Society. Advocacy groups appointed representatives for pre-meeting discussions and the consensus meeting.

Growth Hormone Treatment to Final Height in Turner Syndrome: Systematic Review

PURPOSE

Turner syndrome (TS) is the most common sex chromosomal abnormality found in female subjects. It is a result of a partial or complete loss of one of the X chromosomes. Short stature is a hallmark of TS. Attainment of adult height (AH) within the normal range for height within the general female population represents the usual long-term goal of growth hormone (GH) treatment. The aim of this systematic review was to understand the efficacy of GH therapy on AH of patients with TS.

METHODS

The literature review yielded for analysis 9 articles published from 2010 to 2021. Using the data from this literature search, the goal was to answer 5 questions: (1) What is the efficacy of GH on AH of girls with TS?; (2) Is AH influenced by the age at initiation of GH treatment?; (3) What is the optimal dose of GH to improve AH?; (4) Can the timing of either spontaneous or induced puberty influence AH?; and (5) Can the karyotype influence AH in patients with TS?

FINDINGS

GH therapy and adequate dose could enable patients with TS to achieve appropriate AH compared with the possible final height without therapy. The greatest increase in height during GH therapy occurs in the prepubertal years, and if therapy is continued to AH, there is no further increase. Furthermore, karyotype did not show a predictive value on height prognosis and did not affect the outcome of GH administration or the height gain in girls with TS.

IMPLICATIONS

Even if GH therapy is safe, close monitoring is indicated and recommended. Further evidence is needed to understand what other parameters may influence AH in patients undergoing GH therapy.

Normal bone density but altered geometry in girls with Turner syndrome

OBJECTIVES

Data on bone density and stability in Turner syndrome (TS) are contradictory. A confounding factor for interpretation is short stature. The aim was to measure bone density, geometry and stability in girls with TS compared to idiopathic short stature (ISS).

METHODS

From 1999 to 2008, 59 girls with TS (35 prepubertal) were evaluated by pQCT. Mean age was 8.9 in prepubertal and 17.3 years in adolescent girls. Mean height was -3.1 and -1.8 SDS in prepubertal treatment-free and in adolescent, formerly rhGH-treated girls. For comparison, 18 prepubertal ISS girls were studied (age 7.7 years; height -3.3 SDS). Examination of radius with pQCT (XCT 2000). Cortical (CD) and trabecular density (TD), total bone area (TBA), cortical area (CA), cortical thickness, muscle area and strength strain index (SSI) were determined and compared with height related references.

RESULTS

In prepubertal girls with TS, TD and CD were normal (0.55 and 0.90 SDS) and comparable to ISS (0.95 and 1.53 SDS). TBA was greater in girls with TS than in ISS (0.87 vs. -0.33 SDS) whereas CA was similar (1.48 vs. 1.43 SDS). The SSI was comparable (1.61 vs. 1.56 SDS). Adolescent girls with TS showed similar results with a TD of 0.48 SDS, a CD of -0.32, TBA of 1.99, a CA of -0.05 and an SSI of 0.88 SDS.

CONCLUSIONS

The observations are consistent with normal bone density and stability but altered bone geometry in prepubertal and substituted adolescent girls with TS. This peculiarity may reflect SHOX deficiency. We therefore think that timely and adequate estrogen substitution could prevent bone loss in TS.

The Changing Face of Turner Syndrome

Turner syndrome (TS) is a condition in females missing the second sex chromosome (45,X) or parts thereof. It is considered a rare genetic condition and is associated with a wide range of clinical stigmata, such as short stature, ovarian dysgenesis, delayed puberty and infertility, congenital malformations, endocrine disorders, including a range of autoimmune conditions and type 2 diabetes, and neurocognitive deficits. Morbidity and mortality are clearly increased compared with the general population and the average age at diagnosis is quite delayed. During recent years it has become clear that a multidisciplinary approach is necessary toward the patient with TS. A number of clinical advances has been implemented, and these are reviewed. Our understanding of the genomic architecture of TS is advancing rapidly, and these latest developments are reviewed and discussed. Several candidate genes, genomic pathways and mechanisms, including an altered transcriptome and epigenome, are also presented.

New insights into the comorbid conditions of Turner syndrome: results from a long-term monocentric cohort study

PURPOSE

Many questions concerning Turner syndrome (TS) remain unresolved, such as the long-term complications and, therefore, the optimal care setting for adults. The primary aim of this long-term cohort study was to estimate the incidence of comorbid conditions along the life course.

METHODS

A total of 160 Italian patients with TS diagnosed from 1967 to 2010 were regularly and structurally monitored from the diagnosis to December 2019 at the University Hospital of Bologna using a structured multidisciplinary monitoring protocol.

RESULTS

The study cohort was followed up for a median of 27 years (IQR 12-42). Autoimmune diseases were the comorbid condition with the highest incidence (61.2%), followed by osteoporosis and hypertension (23.8%), type 2 diabetes (16.2%) and tumours (15.1%). Median age of onset ranged from 22 years for autoimmune diseases to 39 years for type 2 diabetes. Malignant tumours were the most prominent type of neoplasm, with a cumulative incidence of 11.9%. Papillary thyroid carcinoma was the most common form of cancer, followed by skin cancer and cancer of the central nervous system. Only one major cardiovascular event (acute aortic dissection) was observed during follow-up. No cases of ischaemic heart disease, heart failure, stroke or death were recorded.

CONCLUSIONS

This cohort study confirms the need for continuous, structured and multidisciplinary lifelong monitoring of TS, thus ensuring the early diagnosis of important comorbid conditions, including cancer, and their appropriate and timely treatment. In addition, these data highlight the need for the increased surveillance of specific types of cancer in TS, including thyroid carcinoma.

Skeletal Characteristics of Children and Adolescents with Turner Syndrome

Turner syndrome (TS) is a chromosomal disorder characterized by a short stature and gonadal dysgenesis, the latter of which requires estrogen replacement therapy (ERT) to induce and maintain secondary sexual characteristics. Insufficient ERT is associated with compromised skeletal health, including bone fragility, in adults with TS. In particular, estrogen insufficiency during adolescence is critical because the acquisition of a defective bone mass during this period results in impaired bone strength later in the life. In addition to bone mass, bone geometry is also a crucial factor influencing bone strength; therefore, a more detailed understanding of the skeletal characteristics of both bone mass and geometry during childhood and adolescence and their relationships with the estrogen status is needed to prevent compromised skeletal health during adulthood in TS. Although a delay in the initiation of ERT is associated with a lower bone mineral density during adulthood, limited information is currently available on the effects of ERT during adolescence on bone geometry. Herein, we summarize the current knowledge on skeletal characteristics in children and adolescents with TS and their relationships with estrogen sufficiency, and discuss the potential limitations of the current protocol for ERT during adolescence in order to achieve better skeletal health in adulthood.

Fracture risk, underlying pathophysiology, and bone quality assessment in patients with Turner syndrome

Turner syndrome (TS), the most common type of X chromosomal disorder, has various, clinical manifestations. Among these, primary hypogonadism, which may lead to osteoporosis, is a life-long health issue. A high prevalence of fractures associated with osteoporosis is a major problem in patients with TS, where it may be 1.4-2.2 times higher than in healthy individuals and increases with age. Among the risk factors associated with fractures in TS, hypogonadism is arguably the most important. Estrogen deficiency due to hypogonadism leads to low bone mineral density (BMD), resulting in a high prevalence of bone fractures. Estrogen replacement therapy (ERT) in patients with TS reportedly improved their BMD. However, other causes of low BMD may exist, given that this condition begins in the prepubertal period in patients with TS. Most previous studies have reported low BMD in patients with TS using dual-energy X-ray absorptiometry (DXA), but this method has some limitations. Areal BMD values assessed by DXA were influenced by bone size and short stature, resulting in an underestimation of BMD. Currently, volumetric BMD values may be accurately obtained using peripheral quantitative computed tomography (pQCT). pQCT, high-resolution pQCT, and the trabecular bone score can also be used to evaluate bone quality, including bone geometry and microarchitecture, in TS. The present review discusses the high fracture risk, role of estrogen deficiency in low BMD, advantages and disadvantages of various bone assessment methods, and characteristics of bone quality in TS.

Musculoskeletal Health in Premature Ovarian Insufficiency. Part Two: Bone

Accelerated bone loss and muscle loss coexist in women with premature ovarian insufficiency (POI), but there are significant gaps in our understanding of musculoskeletal health in POI. This review describes estrogen signaling in bone and its role in skeletal health and disease. Possible mechanisms contributing to bone loss in different forms of POI and current evidence regarding the utility of available diagnostic tests and therapeutic options are also discussed. A literature review from January 2000 to March 2020 was conducted to identify relevant studies. Women with POI experience significant deterioration in musculoskeletal health due to the loss of protective effects of estrogen. In bone, loss of bone mineral density (BMD) and compromised bone quality result in increased fracture risk; however, tools to assess bone quality such as trabecular bone score (TBS) need to be validated in this population. Timely initiation of HRT is recommended to minimize the deleterious effects of estrogen deficiency on bone in the absence of contraindications; however, the ideal estrogen replacement regimen remains unknown. POI is associated with compromised bone health, regardless of the etiology. Ongoing research is warranted to refine our management strategies to preserve bone health in women with POI.

Monitoring and maintaining bone health in patients with Turner syndrome

INTRODUCTION

Subjects affected with Turner Syndrome (TS) suffer low bone mineral density and high risk of fracture from a young age. Estrogen deficiency is considered the main risk factor but other factors, such as intrinsic bone abnormalities, enhanced osteoclastogenesis, vitamin D deficiency and other comorbidities may contribute to the exalted bone fragility.

AREAS COVERED

The authors performed a literature search in PubMed and EMBASE, using selected key words. They focused their search on pathogenetic mechanisms of osteoporosis in TS and updated the diagnosis, prevention and therapeutic interventions.

EXPERT OPINION

Bone health is a concern in subjects with TS, and strategies to prevent osteoporosis and fractures should be considered from childhood. Advice on how to live a healthy lifestyle, including physical activity and correct nutrition, should be given during childhood in order to prevent bone impairment later in life. The screening for vitamin D deficiency should be performed between the ages of 9 and 11, and every 2-3 years thereafter. Early initiation of estrogen replacement therapy (ERT) between 11-12 years of age, prompt titration to the adult dose after 2 years, and long-term follow-up to guarantee compliance with ERT, are the key points of osteoporosis prevention in women with TS.

Turner Syndrome Systematic Review: Spontaneous Thelarche and Menarche Stratified by Karyotype

BACKGROUND

Girls with Turner syndrome (TS) have a high incidence of primary ovarian insufficiency. Recent data show rates of spontaneous thelarche (ST) of 38% and spontaneous menarche (SM) of 15-16%, with higher rates in those with mosaicism.

SUMMARY

We systematically reviewed the literature for evidence regarding rates of ST and SM in TS and evaluated rates based on the type of chromosomal mosaicism. We searched MEDLINE via PubMed, Embase, and the Cochrane Database of Controlled Trials. Reference lists were screened. Studies reporting outcomes of ST and SM in girls with TS, diagnosed by genetic analysis, were included. Data was collected regarding study design, cohort type, cohort age, the number of participants with ST and SM, the individual age at diagnosis of ST and SM, the mean age of patients with ST and SM, sample size, the number of participants with secondary amenorrhea, and karyotype. Key Messages: In total 2,699 patients were assessed for ST and 2,890 for SM from 43 articles. Overall the rates of ST were 32% (95% CI 26.4-38.9) and SM 20.8% (95% CI 19.3-22.4). Girls with X monosomy had the lowest rates of ST (i.e., 13%; 95% CI 8.7-19.7) and SM (i.e., 9.1%; 95% CI 7.3-11.3). Girls with 45,X/47,XXX had the highest rates of ST (i.e., 88.1%; 95% CI 62-97.1) and SM (i.e., 66.2%; 95% CI 49.3-79.6).

CONCLUSIONS

Rates of ST and SM differ by karyotype in TS. When counseling patients, the karyotype should strongly influence discussions regarding pubertal development and the future reproductive potential.

Turner syndrome: mechanisms and management

Turner syndrome is a rare condition in women that is associated with either complete or partial loss of one X chromosome, often in mosaic karyotypes. Turner syndrome is associated with short stature, delayed puberty, ovarian dysgenesis, hypergonadotropic hypogonadism, infertility, congenital malformations of the heart, endocrine disorders such as type 1 and type 2 diabetes mellitus, osteoporosis and autoimmune disorders. Morbidity and mortality are increased in women with Turner syndrome compared with the general population and the involvement of multiple organs through all stages of life necessitates a multidisciplinary approach to care. Despite an often conspicuous phenotype, the diagnostic delay can be substantial and the average age at diagnosis is around 15 years of age. However, numerous important clinical advances have been achieved, covering all specialty fields involved in the care of girls and women with Turner syndrome. Here, we present an updated Review of Turner syndrome, covering advances in genetic and genomic mechanisms of disease, associated disorders and multidisciplinary approaches to patient management, including growth hormone therapy and hormone replacement therapy.

The Efficacy of Long-Term Estrogen Replacement Therapy in Turner Syndrome Women with Premature Ovarian Insufficiency

STUDY OBJECTIVE

To evaluate the efficacy of long-term estrogen replacement therapy (ERT) in uterine development and bone mineral density (BMD) of Turner syndrome (TS) women with premature ovarian insufficiency (POI).

DESIGN AND SETTING

Retrospective study.

PARTICIPANTS AND INTERVENTIONS

Thirty-seven TS women grouped according to ovarian function status: TS women with POI (n = 32), aged 11-26 years, and those with intact ovarian function (IOF; n = 5), aged 13-17 years. TS women with POI underwent ERT.

MAIN OUTCOME MEASURES

Changes in uterine length, anterior-posterior (AP) fundal diameter of the uterus, and BMD were assessed. Statistical methods included Mann-Whitney U test and paired t test.

RESULTS

In TS women with POI, uterine length, AP fundal diameter, and BMD significantly increased after ERT (P < .001). TS women with POI were subdivided into classic (n = 11) and variant (n = 21) types, and there were no significant differences in uterine development and BMD according to types of chromosome. After receiving ERT, AP fundal diameter was significantly longer in classic TS women (P = .034) compared with those with variant type.

CONCLUSION

Long-term ERT increased uterine length (before: 4.4 cm; after: 7.2 cm) and AP fundal diameter (before: 0.9 cm; after: 2.4 cm), and improved BMD in TS women with POI. After ERT, in TS women with POI, uterine length, BMD at lumbar 2-4 and femoral neck were similar to those of TS women with IOF. Therefore, TS women with POI can catch up to those with IOF by receiving ERT.

Turner syndrome and osteoporosis

Turner syndrome is one of the most common sex chromosomal anomalies, characterized by the complete or partial loss of one X chromosome. Females with Turner syndrome are characterized by skeletal abnormalities, short stature and primary ovarian insufficiency. The aim of this narrative review was to identify the underlying mechanisms of osteoporosis in Turner syndrome, summarize its clinical manifestations and provide suggestions regarding the management of osteoporosis. Girls and women with Turner syndrome have lower bone mineral density and a higher fracture rate than healthy individuals. The most important risk factors for osteoporosis are inadequately treated primary ovarian insufficiency, followed by intrinsic bone abnormalities. Comorbidities that further increase the risk of osteoporosis include vitamin D deficiency, celiac disease and inflammatory bowel disease. In addition, hearing problems can predispose to falls. Early initiation of hormone replacement therapy (HRT) at the age of 11-13 years, prompt titration to the adult dose after 2 years and long-term follow-up to ensure compliance with HRT are the cornerstones of osteoporosis prevention in women with Turner syndrome.

Turner Syndrome: transition from childhood to adolescence

Transition from pediatric to adult care for young women with Turner Syndrome (TS) is characterized by high drop-out rates and inadequate follow-up, leading to increased morbidity and mortality. The complexity of the health issues young women with TS face or new problems that may arise warrants a well-structured and efficiently coordinated gradual transition plan, which is adapted to the individual needs of the emerging young adult and is based on interdisciplinary communication between physicians. In order to achieve a high level of care, it is important for the patient to be sincerely informed about her condition but also supported throughout this critical period of rising responsibility and autonomy by an experienced, multidisciplinary team. In this review, we present the basic concepts that should characterize transition and the major health issues that should be thoroughly addressed, including growth, Hormone Replacement Treatment and fertility options, cardiovascular disease, bone health, gastrointestinal disorders, autoimmunity, orthopaedic and ENT issues, as well as the overall psychological well-being of the young adult with TS.

Eldecalcitol increases bone mass in patients with Turner syndrome who have insufficient bone mass acquisition after estrogen replacement therapy

Most patients with Turner syndrome (TS) exhibit amenorrhea due to premature ovarian failure. Therefore, estrogen replacement therapy (ERT) is required; however, even after undergoing ERT, it is not rare for bone mass acquisition to be insufficient. This study was conducted in two stages, involving a cross-sectional and a prospective interventional study. We recruited 52 TS patients undergoing ERT due to amenorrhea (categorized into low (LB group; n = 23), and normal (NB group; n = 29) bone mass groups) and 7 TS patients who maintained ovarian function (spontaneous menstrual cycle group (MC group)) as controls. We compared bone associated markers between the three groups (LB, NB, and MC). Furthermore, the LB group had concomitant treatment with eldecalcitol (ELD) and ERT for 12 months. The bone mineral density (BMD) of the lumber spine (L2-4) and the bone metabolism markers were then compared before and after the treatment. The bone metabolism markers were significantly higher in the LB group than the NB and MC groups. Furthermore, with the concomitant use of ELD and ERT in the LB group, BMD increased significantly (pre-treatment 0.710 ± 0.056 g/cm² vs. 0.736 ± 0.062 g/cm² after 12 months; p < 0.001). TS patients with insufficient bone mass acquisition even after ERT were characterized by a higher turnover in bone metabolism. Therefore, the concomitant use of ELD was considered an effective adjuvant therapy for increasing bone mass.

Prevalence of diverse complications and its association with karyotypes in Japanese adult women with Turner syndrome-a questionnaire survey by the Foundation for Growth Science

The reported prevalence of complications in Turner Syndrome (TS) was highly variable because of the rarity and the limited numbers analyzed. Again, possible presence of other complications that are not described as specific for TS, is also speculated. To resolve these issues, a questionnaire survey was conducted in hGH treated 492 patients with adult TS (17-42 years). The possible association with these complications and karyotypes were also analyzed. The complications and their prevalence were as follows: chronic thyroiditis (25.2%), inflammatory bowel disease (1.8%), congenital cardiovascular anomaly (11.8%), urinary tract malformation (11.8%), low bone mineral density (BMD) (42.9%), scoliosis (8.4%), hearing loss (6.2%), epilepsy (2.8%) and schizophrenia (0.9%). The majority of prevalence of these diseases in TS was higher than in the general population. In distribution, the most frequent karyotype was 45,X monosomy (28.9%), followed by 45,X/46,X,Xi (16.9%), 46,X,Xi (9.1%), and 45,X/46,XX (6.3%), while other mosaic 45,X was noted in 29.9%. Regarding the karyotype, cardiovascular anomaly was more frequent in the 45,X group and less in the 46,X,Xi group. Urinary tract malformation and epilepsy were frequently associated with the chromosome 45,X. The prevalence of low BMD was noticed more in the chromosome 46,X,Xi and 45,X/46,X,Xi, and less in other mosaic 45,X. In conclusion, the more exact prevalence of diverse complications was clarified and it exceeded the prevalence of the majority of complications in general population. As novel findings, it was observed that the prevalence of epilepsy was significantly high, and epilepsy and low BMD were frequently associated with the specific karyotypes.

A 6-Year Follow-Up of Fracture Incidence and Volumetric Bone Mineral Density Development in Girls With Turner Syndrome

CONTEXT

Patients with Turner syndrome (TS) are at risk for osteoporotic fractures.

OBJECTIVE

The aims of this study were to assess the incidence of clinically important fractures in girls with TS and prospectively describe the development of volumetric bone mineral density (BMD).

DESIGN

Peripheral quantitative computerized tomography (pQCT) of the radius every other year over the 6 years of observation.

SETTING

Government-funded university referral center.

PARTICIPANTS

Thirty-two girls with TS, aged 6 to 16 years, were included in the analyses. Fracture incidence was compared with the data in the general population. Bone density and strength were compared with data from 185 healthy girls.

OUTCOMES

The main clinical outcome was the fracture occurrence. The secondary outcomes were the changes in Z-scores of the bone parameters.

RESULTS

Three girls with TS sustained four fractures during 6 years of observation. The fracture rate in TS was not substantially higher than the downward-biased fracture-rate estimate from age-matched, healthy controls (P = 0.48). Whereas the trabecular BMD Z-score decreased with age (β estimate -0.21 ± 0.04, P < 0.001), total bone cross-sectional area correspondingly increased (+0.16 ± 0.04, P < 0.001), which led to normal bone strength. A positive history of incident fractures was not significantly associated with any of the pQCT-derived bone parameters.

CONCLUSIONS

Current pediatric TS patients that are treated with growth hormone and estrogens are not at risk for osteoporotic fractures. Low BMD in TS may be counterweighted by enlarged bone radius, which leads to normal bone strength at the appendicular skeleton.

Clinical practice guidelines for the care of girls and women with Turner syndrome: proceedings from the 2016 Cincinnati International Turner Syndrome Meeting

Turner syndrome affects 25-50 per 100,000 females and can involve multiple organs through all stages of life, necessitating multidisciplinary approach to care. Previous guidelines have highlighted this, but numerous important advances have been noted recently. These advances cover all specialty fields involved in the care of girls and women with TS. This paper is based on an international effort that started with exploratory meetings in 2014 in both Europe and the USA, and culminated with a Consensus Meeting held in Cincinnati, Ohio, USA in July 2016. Prior to this meeting, five groups each addressed important areas in TS care: 1) diagnostic and genetic issues, 2) growth and development during childhood and adolescence, 3) congenital and acquired cardiovascular disease, 4) transition and adult care, and 5) other comorbidities and neurocognitive issues. These groups produced proposals for the present guidelines. Additionally, four pertinent questions were submitted for formal GRADE (Grading of Recommendations, Assessment, Development and Evaluation) evaluation with a separate systematic review of the literature. These four questions related to the efficacy and most optimal treatment of short stature, infertility, hypertension, and hormonal replacement therapy. The guidelines project was initiated by the European Society for Endocrinology and the Pediatric Endocrine Society, in collaboration with The European Society for Pediatric Endocrinology, The Endocrine Society, European Society of Human Reproduction and Embryology, The American Heart Association, The Society for Endocrinology, and the European Society of Cardiology. The guideline has been formally endorsed by the European Society for Endocrinology, the Pediatric Endocrine Society, the European Society for Pediatric Endocrinology, the European Society of Human Reproduction and Embryology and the Endocrine Society. Advocacy groups appointed representatives who participated in pre-meeting discussions and in the consensus meeting.

Bone Fragility in Turner Syndrome: Mechanisms and Prevention Strategies

Bone fragility is recognized as one of the major comorbidities in Turner syndrome (TS). The mechanisms underlying bone impairment in affected patients are not clearly elucidated, but estrogen deficiency and X-chromosomal abnormalities represent important factors. Moreover, although many girls with TS undergo recombinant growth hormone therapy to treat short stature, the efficacy of this treatment on bone mineral density is controversial. The present review will focus on bone fragility in subjects with TS, providing an overview on the pathogenic mechanisms and some prevention strategies.

The muscle-bone interaction in Turner syndrome

OBJECTIVES

Turner syndrome (TS) is associated with an increased fracture rate due to reduced bone strength, which is mainly determined by skeletal muscle force. This study aimed to assess the muscle force-bone strength relationship in TS and to compare it with that of healthy controls.

METHODS

This study included 39 girls with TS and 67 healthy control girls. Maximum muscle force (Fmax) was assessed through multiple one-legged hopping with jumping mechanography. Peripheral quantitative computerized tomography assessed the bone strength index at the tibial metaphysis (BSI 4) and the polar strength-strain index at the diaphysis (SSI polar 66). The effect of TS on the muscle-bone unit was tested using multiple linear regression.

RESULTS

TS had no impact on Fmax (p=0.14); however, a negative effect on bone strength (p<0.001 for BSI 4 and p<0.01 for SSI polar 66) was observed compared with healthy controls. Bone strength was lower in the TS group (by 18%, p<0.01, for BSI 4 and by 7%, p=0.027, for SSI polar 66), even after correcting for Fmax.

CONCLUSIONS

Similar muscle force induces lower bone strength in TS compared with healthy controls, which suggests altered bone-loading sensitivity in TS.

Artificially low cortical bone mineral density in Turner syndrome is due to the partial volume effect

We aimed to show that the decrease in the cortical bone mineral density (BMD) in the radius in Turner syndrome (TS) is artificially caused by the partial volume effect. We confirmed that the partial volume effect-corrected cortical BMD is not decreased in TS compared to in the healthy controls. Other factors are responsible for the increased fracture rate in TS.

INTRODUCTION

Decreased cortical bone mineral density (BMD) has been reported in Turner syndrome (TS), using peripheral quantitative computerised tomography, and it is perceived as one of the major factors leading to increased fracture risk. We tested the hypothesis that low cortical BMD in the radius is caused artificially by the partial volume effect.

METHODS

A cross-sectional study was conducted at the university hospital referral centre between March and October 2013. Thirty-two participants with TS who consented to the study were included (mean age 15.3 ± 3.2 years). We assessed the cortical BMD in the radius as well as the tibia, where the cortex is thicker compared with the radius.

RESULTS

Whereas the cortical BMD was decreased in the radius (mean ± SD Z-score -0.6 ± 1.5, p = 0.037), it was increased in the tibia (mean Z-score 0.83 ± 1.0, p < 0.001). After correcting the cortical BMD for the partial volume effect, the mean Z-score was normal in the radius in TS (0.4 ± 1.3, p = 0.064). The corrected cortical BMD values were similar in the radius and tibia (1108 ± 52 vs. 1104 ± 48, group difference p = 0.75).

CONCLUSIONS

The cortical BMD is not decreased in TS. The partial volume effect is responsible for previous findings of decreased cortical BMD in the radius. Altered bone geometry or other factors rather than low cortical BMD likely play a role in the increased fracture risk in TS.

Current concepts surrounding bone health and osteoporosis in Turner syndrome

Although Turner syndrome is the most common chromosomal disorder in women, a great deal remains to be understood in terms of optimal patient care, particularly as it relates to bone health. These women are known to be at risk for osteoporosis and fracture later in life as a result of a multitude of risk factors. While estrogen replacement and childhood growth hormone treatment are now considered standard of care, little is known of the role of further interventions to prevent and treat osteoporosis in these women. This review aims to highlight the specifics of bone health in Turner syndrome. We explore the bone diagnostic modalities and therapeutic interventions available and their role in the coming years of bone health management in this unique population.

Bone mineral density in Turner's syndrome and the influence of pubertal development

AIM

To describe bone mineral density at the lumbar spine in a group of girls with Turner's syndrome and determine its relation to pubertal development.

METHODS

Girls with Turner's syndrome aged over 12 years were invited to participate in the study. All participants underwent auxology, pubertal assessment and laboratory evaluation. Bone mineral density was estimated by dual-energy X-ray absorptiometry. Bone mineral apparent density was then calculated, and the results were compared with age-matched Dutch reference data.

RESULTS

We studied 32 girls with Turner's syndrome, mean (SD) [range] age 16.7 (2.6) [12.4-20.2] years and height 148.3 (9.0) [126-159.2] cm. Bone mineral apparent density lumbar spine values were -0.87 SD, significantly lower than in the reference population (p <0.001). Bone mineral apparent density values were positively and significantly associated with breast Tanner stages and postmenarcheal status, but not spontaneous puberty. However, no significant association was found between bone mineral apparent density and karyotype, growth hormone or timing of oestrogen therapy.

CONCLUSION

Girls with Turner's syndrome have lower bone mineral apparent density values at the lumbar spine, even after correcting for size, compared with an age- and sex-matched general population. Pubertal development has significant impact on bone mineral apparent density in girls with Turner's syndrome.

Clinical review: Turner syndrome: updating the paradigm of clinical care

CONTEXT

Turner syndrome (TS), in which there is loss of all or part of one sex chromosome, occurs in one in 2500 live-born females and is associated with characteristic findings. Detailed healthcare checklists and screening guidelines are commonly used to detect known complications affecting individuals with TS. Even with the use of these guidelines, there remains an increased morbidity and mortality seen in TS as compared to the general population, leading to significant controversy on optimal management of several aspects of TS.

EVIDENCE ACQUISITION AND SYNTHESIS

A PubMed search of articles from the past 15 yr identified available studies related to the diagnosis and management of common issues related to TS as well as important historical articles. This review summarizes studies through January 2012 and highlights recent developments.

CONCLUSIONS

There remain many areas of uncertainty in the diagnosis and management of TS. Generalizations from experience in the care of other conditions in isolation (such as poor growth, follow-up of cardiac disease, or the treatment of ovarian failure) cannot be broadly applied when caring for individuals with TS. Specific differences include treatment of growth failure as early as possible; acquisition of adequate baseline cardiac studies, followed by serial magnetic resonance imaging, targeted to identify findings unique to TS that address the increased risk of aortic dissection; initiation of hormone replacement at the normal age of puberty, preferentially with transdermal estradiol; and detailed patient counseling to explain the long-term health risks commonly associated with this disorder. A revised paradigm of care using a standardized multidisciplinary evaluation, supplementing screening tests as advocated by expert opinion guidelines, can aid clinicians in interpreting the results of diagnostic testing in the context of TS. This approach optimizes medical care for women with TS and may reduce the increased morbidity and mortality currently seen in this population.

Sex hormone replacement in Turner syndrome

The cardinal features of Turner syndrome (TS) are short stature, congenital abnormalities, infertility due to gonadal dysgenesis, with sex hormone insufficiency ensuing from premature ovarian failure, which is involved in lack of proper development of secondary sex characteristics and the frequent osteoporosis seen in Turner syndrome. But sex hormone insufficiency is also involved in the increased cardiovascular risk, state of physical fitness, insulin resistance, body composition, and may play a role in the increased incidence of autoimmunity. Severe morbidity and mortality affects females with Turner syndrome. Recent research emphasizes the need for proper sex hormone replacement therapy (HRT) during the entire lifespan of females with TS and new hypotheses concerning estrogen receptors, genetics and the timing of HRT offers valuable new information. In this review, we will discuss the effects of estrogen and androgen insufficiency as well as the effects of sex HRT on morbidity and mortality with special emphasis on evidence based research and areas needing further studies.

Bone size and density measurements in prepubertal children with Turner syndrome prior to growth hormone therapy

Using computed tomography (CT), we found the decreases in bone size of vertebrae and femur, cortical bone area (CBA) of femur and bone density (BD) of vertebrae in prepubertal female with Turner syndrome (TS) compared to those of controls.

INTRODUCTION

Bone mineral density results from previous studies utilizing single-photon absorptiometry (SPA) or dual-energy X-ray absorptiometry (DXA) in children with TS are controversial. The present study used CT to assess the differences in cancellous and cortical bone size and BD between prepubertal TS patients prior to growth hormone therapy and historical age and ethnicity-matched female controls.

METHODS

Anthropometrics and CT bone measurements including cross-sectional area (CSA) and BD of lumbar vertebrae and femur and CBA of femur in prepubertal TS females were reviewed and compared with those in controls.

RESULTS

Twenty-two prepubertal TS patients had delayed bone age, were shorter and lighter than controls (Ps < 0.001). After adjusting for weight, height and skeletal age, vertebral BD and CBA of the femur were lower in patients than in controls (P < 0.001 and P = 0.021, respectively). However, after additional adjusting for puberty, results were not different from controls. While a positive correlation between vertebral BD and age was noted in controls (r = 0.367, P = 0.092), a significant negative correlation was noted in patients (r = -0.615, P = 0.002).

CONCLUSIONS

While the decrease in vertebrae and femur sizes of patients with TS appeared to be secondary to their small body size, the decreased BD of vertebrae and CBA of femur were likely secondary to estrogen deficiency.

The effect of growth hormone treatment on bone mineral density in prepubertal girls with Turner syndrome: a multicentre prospective clinical trial

BACKGROUND

Patients with Turner syndrome (TS) are treated with GH to increase adult height. Although it is well established that GH promotes longitudinal bone growth, the effects of GH treatment on bone density are less clear.

OBJECTIVE

To determine how GH treatment affects trabecular bone mineral density (BMD) in girls with TS at prepubertal ages in a prospective multicentre study.

PATIENTS AND METHOD

Twenty-two patients with TS in the prepubertal period with a mean age of 9.8 +/- 2.5 (range 3.6-12.8) years were included in the study. All girls with TS underwent measurement of areal BMD using dual-energy X-ray absorptiometry (DXA) to obtain pretreatment anteroposterior (AP) lumbar spine values at L1-L4. Patients received GH (Genotropin) subcutaneously for 1 year at a dose of 0.05 mg/kg/day. Height and weight were measured at 3-monthly intervals. The AP lumbar spine areal BMD was remeasured using the same technique after 1 year of treatment. Lumbar spine BMD Z-scores and volumetric BMD (vBMD) Z-scores were calculated using national standards.

RESULTS

The height SDS of our cases showed a significant increase with GH therapy. The pretreatment lumbar spine (L1-L4) BMD Z-score was -1.2 +/- 1.2 SD and the vBMD Z-score was -0.8 +/- 1.6 SD. There were no significant changes in these values after 1 year of GH treatment. Prepubertal TS girls more than 11 years of age had lower vBMD Z-scores (-1.7 +/- 1.7 SD) than the girls aged less than 11 (-0.1 +/- 1.0 SD) (P < 0.05) at the onset of therapy. No significant changes were observed in these values after 1 year of GH therapy.

CONCLUSIONS

Osteopaenia becomes apparent in prepubertal TS patients as they reach pubertal age. BMD evaluation may be necessary in these prepubertal TS girls at diagnosis. Short-term GH therapy in these TS patients does not have a significant effect on bone density when measured at a site with a predominance of trabecular bone.

Disproportional geometry of the proximal femur in patients with Turner syndrome: a cross-sectional study

OBJECTIVE

Patients with Turner syndrome (TS) have altered growth and increased risk of osteoporosis due to oestrogen deficiency and possibly a host of other factors. Thus, TS patients have a 4.9-fold increased risk of femoral neck fractures. Most patients are treated with oestrogen during puberty and adolescence to facilitate pubertal development and prevent secondary osteoporosis. The geometry of the hip is a predictor for hip fractures independent of bone mineral density (BMD). The purpose of the present study was to investigate the variation of the geometry of the hip in patients with TS in comparison with healthy controls.

PATIENTS

The study population comprised 58 patients with TS (aged 22-67 years) and 60 age-matched healthy women (aged 21-65 years).

MEASUREMENTS

Hip axis length (HAL), neck width (NW), neck shaft angle (NSA), and femoral head-radius (HR) on dual-energy X-ray absorptiometry (DXA) screen images. These parameters related to age of oestrogen supplementation, menarche, and duration of oestrogen exposure.

RESULTS

Height was 146.6 +/- 6.9 cm and 167.1 +/- 6.2 cm (P < 0.1) and weight 57.4 +/- 13.9 kg and 62.3 +/- 8.3 kg (P < 0.001) in patients and controls, respectively. After adjustment for differences in height, HAL was not significantly different (9.4 +/- 0.5 vs. 9.5 +/- 0.5 cm; NS) in TS compared with controls while NW was significantly increased (3.5 +/- 0.4 cm vs. 3.3 +/- 0.2 cm, P < 0.001), NSA was similar (129 +/- 4 degrees vs. 130 +/- 4 degrees , NS), and HR was significantly decreased (4.1 +/- 0.4 vs. 4.5 +/- 0.3 cm, P < 0.001). The duration of oestrogen exposure was significantly shorter among TS, but did not correlate significantly with the geometrical parameters in either TS or controls.

CONCLUSION

Our data demonstrates that hip geometry is disproportionate in TS compared with normal controls. The altered hip geometry, however, cannot explain the increased risk of hip fracture in TS.

Normal DXA bone mineral density but frail cortical bone in Turner's syndrome

CONTEXT

Patients with Turner's syndrome have normal bone mineral density by dual energy X-ray absorptiometry (DXA), but a predisposition for fractures. Quantitative ultrasonography (QUS) measures cortical bone strength.

OBJECTIVE

To compare QUS with DXA in patients with Turner's syndrome.

PATIENTS AND METHODS

Twenty-seven Turner's syndrome patients, aged 21.1 +/- 6.3 years (mean +/- SD), were evaluated by DXA, measuring two-dimensional bone mineral density (BMD), and QUS, measuring speed of sound (SOS) of the radius and tibia. The results were compared to sex- and age-matched (Ctr A, n = 53) and height-matched (Ctr B, n = 34) control groups.

RESULTS

Fracture incidence per 1000 women years was 4.76 in Ctr A, 5 in Ctr B and 7.69 in Turner's patients. In Turner's syndrome patients, QUS results were significantly lower than in controls, whereas DXA Z-scores were not different from reference values. Correlation between tibia and radius SOS and height and age in controls (P < 0.0001) was not evident in Turner's syndrome. Oestrogen or growth hormone therapy had no effect on either QUS or DXA parameters.

CONCLUSIONS

Bone fragility in Turner's syndrome is reflected by low SOS but not by DXA BMD. Low QUS, which assesses the cortical bone only, supports a defect in cortical bone in Turner's syndrome. Lack of SOS correlation with age, height and hormonal therapy in Turner's syndrome suggests a primary bone defect, rather than enhanced resorption of endocrine origin.

The effects of growth hormone treatment on bone mineral density and body composition in girls with turner syndrome

BACKGROUND

Many girls with Turner syndrome (TS) are treated with GH to increase adult height. In addition to promoting longitudinal bone growth, GH has effects on bone and body composition.

OBJECTIVE

The objective was to determine how GH treatment affects bone mineral density (BMD) and body composition in girls with TS.

METHOD

In a cross-sectional study, we compared measures of body composition and BMD by dual energy x-ray absorptiometry, and phalangeal cortical thickness by hand radiography in 28 girls with TS who had never received GH and 39 girls who were treated with GH for at least 1 yr. All girls were participants in a National Institutes of Health (NIH) Clinical Research Center (CRC) protocol between 2001 and 2006.

RESULTS

The two groups were similar in age (12.3 yr, sd 2.9), bone age (11.5 yr, sd 2.6), and weight (42.8 kg, sd 16.6); but the GH-treated group was taller (134 vs. 137 cm, P = 0.001). The average duration of GH treatment was 4.2 (sd 3.2) yr (range 1-14 yr). After adjustment for size and bone age, there were no significant differences in BMD at L1-L4, 1/3 radius or cortical bone thickness measured at the second metacarpal. However, lean body mass percent was higher (P < 0.001), whereas body fat percent was lower (P < 0.001) in the GH-treated group. These effects were independent of estrogen exposure and were still apparent in girls that had finished GH treatment at least 1 yr previously.

CONCLUSIONS

Although GH treatment has little effect on cortical or trabecular BMD in girls with TS, it is associated with increased lean body mass and reduced adiposity.

Clinical practice in Turner syndrome

Turner syndrome (TS) is a common genetic disorder, resulting from the partial or complete absence of one sex chromosome, and occurring in approximately 50 per 100,000 liveborn girls. TS is associated with reduced adult height and with gonadal dysgenesis, leading to insufficient circulating levels of female sex steroids and to infertility. Morbidity and mortality are increased in TS but average intellectual performance is within the normal range. A number of recent studies have allowed new insights to be gained with respect to epidemiology, genetics, cardiology, endocrinology and metabolism. Elucidation of the effects of short stature homeobox protein deficiency has explained some of the phenotypic characteristics in TS, principally short stature. Treatment with growth hormone during childhood and adolescence allows a considerable gain in adult height, although the consequences of this treatment in the very long term are not clear. Puberty must be induced in most cases, and female sex hormone replacement therapy (HRT) is given during adult years. The optimal dose of HRT has not been established and, likewise, the benefits and drawbacks of HRT have not been thoroughly evaluated. The risks of type 2 diabetes, type 1 diabetes, hypothyroidism, osteoporosis, congenital heart disease, hypertension, ischemic heart disease, aortic dilatation and dissection, inflammatory bowel disease and celiac disease are clearly elevated, and proper care during adulthood is important. Currently no firm guidelines for diagnosis exist. In conclusion, TS is a condition associated with a number of diseases and conditions that are reviewed in the present paper. Individuals with TS need life-long medical attention.

Healthcare for adolescents with Turner syndrome

This review paper highlights important healthcare issues for adolescents with Turner Syndrome. Turner Syndrome potentially affects multiple organ systems including: cardiovascular, renal, endocrine, neurologic, gastrointestinal, skin, skeletal, auditory, and reproductive systems. Congenital and acquired cardiac defects remain the most significant health problem faced by women with Turner Syndrome.

Investigation of cardiac status and bone mineral density in Turner syndrome

This review highlights recent developments in the detection and management of congenital heart disease and osteoporosis in patients with monosomy X, or Turner syndrome (TS). Magnetic resonance angiography (MRA) using gadolinium as a contrast agent demonstrates a higher prevalence and greater diversity of congenital cardiovascular defects than previously recognized in TS. Almost 50% of girls and women with TS have marked tortuosity or ectasia of the aortic arch, suggesting that these individuals may be at greater risk for aneurysm formation or dissection and therefore require closer monitoring. MRA also reveals that major venous anomalies are common in TS, with partial anomalous pulmonary venous return and persistent left superior vena cava each found in about 13% of patients. MR imaging even without contrast is a valuable complement to routine cardiac ultrasound in detecting abnormalities of the aortic valve. Abnormal electrocardiographic findings, including prolongation of the QTc interval, have recently been documented in many individuals with TS. Conduction and repolarization abnormalities have not been associated with congenital anatomic defects and are as common in young girls as adults. The clinical significance of these electrophysiological findings is unknown at present, but attention to the ECG in TS is important, particularly in monitoring the QTc when prescribing drugs associated with QT prolongation. Patients with TS are at high risk for osteoporosis as a result of premature ovarian failure and intrinsic bone abnormalities specific to the syndrome. Low cortical bone mineral density (BMD) is apparent in prepubertal girls, and it remains low in adults, independent of estrogen treatment and other hormonal factors. The low mineralization of cortical bone in TS may be associated with a small increased fracture risk, but no treatments are known to increase cortical bone mineral content in TS. Trabecular BMD is normal in TS women who have received continuous estrogen treatment from their mid-teens, although areal densitometry scores may be misleadingly low in very small patients. However, young women with ovarian failure who have not received estrogen treatment for extended periods of time are at high risk for osteoporosis of trabecular bone of the spine, with associated compression fractures and height loss. Therefore, judicious management of estrogen therapy to prevent osteoporosis while minimizing estrogen-associated adverse events is a challenging aspect of care for girls and women with TS.

Turner syndrome in adulthood

Turner syndrome is a common genetic disorder associated with abnormalities of the X chromosome and occurs in about 50 per 100,000 liveborn girls. It is associated with reduced adult height, gonadal dysgenesis and thus insufficient circulating levels of female sex steroids and infertility. Morbidity and mortality are increased throughout the lifespan. The average intellectual performance is within the normal range. A number of recent clinical studies have given new insight particularly into the adult phase of Turner syndrome. Treatment with growth hormone during childhood and adolescence enables a considerable gain in adult height. In most cases puberty has to be induced and female sex hormone replacement therapy is given during adulthood. Type 2 diabetes is often seen, and hypertension and associated cardiovascular disorders are frequent. The proper treatments of these disorders have not been firmly established. Since the risk of cardiovascular and endocrinological disease is clearly elevated, proper care during adulthood is crucial. Cognition and social functioning are altered in Turner syndrome.

Estudio de la masa ósea en el síndrome de Turner

OBJECTIVES

To evaluate bone mass in patients with Turner syndrome by measuring metacarpal cortical thickness and bone diameter before and after treatment with oxandrolone, growth hormone (GH) and estrogens.

PATIENTS AND METHODS

We studied 42 girls with Turner syndrome divided into the following groups: group I: 31 patients aged between 3 and 15 years who were not treated before the study; group II: 15 patients treated with GH at start ages of between 5.2-14.8 years; group III: 17 patients treated with oxandrolone at start ages of between 5.3 and 15.2 years; group IV: 17 patients treated with estrogens and divided in different subgroups: IVa: seven patients treated with GH and estrogens at start ages of between 6.1 and 12.9 years; IVb: five patients treated with oxandrolone and estrogens at start ages of between 13.4 and 17.4 years, and IVc: five patients treated with oxandrolone, GH and estrogens at start ages of between 10.3 and 16.1 years. Bone mass was evaluated by a radiogrammetric method that measures the cortical thickness and bone diameter of three metacarpal bones with a magnifying glass. The results are expressed in SD according to Spanish longitudinal reference standards (Andrea Prader Center of Growth and Development) from 0.5 to 9 years of age and to Swiss standards from the age of 10 years onwards. Statistical significance was set at p < 0.05.

RESULTS

Group I (spontaneous development): cortical development was below the mean and was significantly diminished at the ages of 9, 13 and 14 years; bone diameter was decreased in relation to controls throughout the study period; group II (impact of GH treatment): cortical thickness showed a nonsignificant increase of 0.6 SD from baseline to years 3-4 of treatment and diameter increased by 0.5 SD from baseline to year 4 of treatment; group III (impact of oxandrolone): cortical thickness increased from -0.8 SD before treatment to 0.0 SD at years 2 and 3 of treatment; bone diameter increased from -1.5 SD at baseline to -1 SD at 3 years of treatment; group IV (impact of treatment with estrogens); IVa: cortical thickness and bone diameter increased; IVb: cortical thickness increased but bone diameter was unchanged; IVc: both cortical thickness and bone diameter increased.

CONCLUSIONS

The results of this study show that cortical thickness and bone diameter are decreased in untreated girls with Turner syndrome; cortical thickness was significantly decreased at the ages of 9, 13 and 14 years, while bone diameter was diminished at all ages, suggesting the presence of osteopenia in these patients. GH treatment produced a nonsignificant increase in cortical thickness and bone diameter. Oxandrolone treatment showed a positive effect on bone mass during the first few years of therapy. Because of the small number of patients, conclusions cannot be reached on the effectiveness of estrogens.

Hormonal therapies for individuals with intersex conditions: protocol for use

Hormonal therapy forms part of the treatment of every intersex condition. For some conditions, such as salt-wasting congenital adrenal hyperplasia, hormonal replacement therapy is life saving because hormones necessary for survival (cortisol and aldosterone) are replaced. In contrast, other hormones such as androgens or mineralocorticoids are secreted in excessive amounts in congenital adrenal hyperplasia due to an enzyme imbalance, and the role of hormonal therapy is to suppress the unwanted hormone excess by exerting negative feedback. For patients with one of the many causes of hypogonadism, sex hormone replacement therapy may be prescribed to stimulate sexual development: growth of a hypoplastic penis in a young boy, pubertal changes (male or female), psychosexual development, and adult sexual behavior. It has equally important and highly beneficial effects on bone mineral density. Hormonal therapy is also used to treat the unborn child. For the last 20 years, prenatal dexamethasone treatment administered to the pregnant woman has been used to prevent the development of ambiguous genitalia in females with 21-hydroxylase deficiency. Outcome studies show this treatment to be well tolerated and, in general, efficacious. Intersex conditions are, however, difficult to treat because they may intrinsically perturb complex aspects of the person's gender identity, gender-role behavior, sexual orientation, sexual functioning, and psychologic adjustment. Furthermore, decisions made about the sex of an infant by doctors and parents do not always turn out to be correct; the person may grow up feeling uncertain about his or her gender identity, or worse still, harbor a sense of outrage about their life and treatment experiences. Such a person will have definite views about hormonal therapy when the time comes and skillful counseling will be needed. A vigorous debate about ethical aspects of current medical practices relating to intersex conditions has been waged for the last 7 years between certain patient advocacy organizations and the medical profession, and is expected to continue for some time. The quality of the debate will be improved by evidence. The results of a number of long-term follow-up studies have been published, and more are expected. The published studies show mixed, but mainly encouraging, results.

Epidemiological, endocrine and metabolic features in Turner syndrome

Turner syndrome is one of the more common genetic disorders, associated with abnormalities of the X chromosome, and occurring in about 50 per 100,000 liveborn girls. Turner syndrome is usually associated with reduced adult height, gonadal dysgenesis, and thus insufficient circulating levels of female sex steroids, and infertility. A number of other signs and symptoms are seen more frequent with the syndrome. Morbidity and mortality is increased. The average intellectual performance is within the normal range. With respect to epidemiology, cardiology, endocrinology and metabolism a number of recent studies have allowed new insight. Treatment with GH during childhood and adolescence allows a considerable gain in adult height. Puberty has to be induced in most cases, and female sex hormone replacement therapy is given during adult years. The proper dose of HRT has not been established, and, likewise, benefits and/or drawbacks from HRT has not been thoroughly evaluated. Since the risk of cardiovascular and endocrinological disease is clearly elevated, proper care during adulthood is emphasized. In summary, Turner syndrome is a condition associated with a number of disease and conditions which are reviewed in present paper.

The relationship between lean body mass and bone mineral content in paediatric health and disease

INTRODUCTION

The correct interpretation of DXA data is critical to the diagnosis and management of children with suspected bone disease. This study examines the various influences on bone mineral content (BMC), as measured by dual-energy X-ray absorptiometry (DXA).

MATERIALS AND METHODS

Six hundred and forty-six healthy school children and forty-three children with chronic diseases, aged 5-18 years, had their lumbar spine and whole body measured using a Lunar DPX-L DXA scanner.

RESULTS

Stepwise linear regression identified lean body mass (LBM) as the strongest single predictor of BMC in the lumbar spine and the total body. A significant gender difference was observed in the relationship between BMC and LBM with girls having significantly more bone per unit LBM from 9 years of age in the spine and 13 years of age in the total body. To investigate the relationship between LBM and BMC in children with chronic disease, a two-stage algorithm based upon calculation of Z scores from the normative data was applied. Stage 1 assessed LBM for height and stage 2 assessed BMC for LBM. Ten children with spinal muscular atrophy had a mean LBM for height Z score of -1.8(1.4) but a mean BMC for LBM Z score of 1.2(1.3) indicating their primary abnormality was reduced muscle mass (sarcopenia) with no evidence of osteopenia. In contrast, 21 children with osteogenesis imperfecta had a mean LBM for height Z score of 0.4(1.7) but a mean BMC for LBM Z score of -2.5(1.8) indicating normal LBM for size but significantly reduced BMC for LBM (i.e. osteopenia) confirming a primary bone abnormality. A third group consisting of 12 children with low trauma fractures demonstrated little evidence of sarcopenia [mean LBM for height Z score -1.1(2.1)] but significant osteopenia [mean BMC for LBM Z score -1.9(1.5)].

CONCLUSION

The results from this study demonstrate how the relationship between height and lean body mass, and lean body mass and bone mineral content can be a useful method of diagnosing osteoporosis in children and how the relationships can be used to identify if the primary abnormality is in muscle or bone.

Importance of estrogen on bone health in Turner syndrome: a cross-sectional and longitudinal study using dual-energy X-ray absorptiometry

Osteoporosis and fractures are features in adults with Turner syndrome (TS). Using dual-energy x-ray absorptiometry, correcting bone mineral content (BMC) for height and lean mass (LTM) avoids misclassification of short children as osteopenic. Total body (TB), lumbar spine (LS), and femoral neck (FN) dual-energy x-ray absorptiometry scans were performed on 83 patients with TS (aged 4-24 yr). A prepubertal subgroup (n = 17) receiving GH was followed for 24 months. Age z-scores for height, TB BMC, LTM, the BMC/LTM ratio, and LS volumetric bone mineral density (vBMD) decreased significantly (P < 0.001) with age in prepubertal subjects (n = 51) but were constant in the combined pubertal and postmenarchal group (n = 32). Osteopenia was found in 14.5% (TB), 15.8% (LS), and 28.4% (FN) of patients. In the longitudinal subgroup, TB BMC z-scores decreased by -0.28 (0.31) in subjects remaining prepubertal (n = 11) but increased by 0.71 (0.56) in subjects entering puberty (n = 6; P = 0.007). The z-scores for height and LTM increased in both groups. Our results show a height-independent prepubertal decrease in bone mass accrual, which ceased with puberty. Optimizing bone mass in TS may require earlier induction of puberty than currently recommended. However, reduced FN volumetric bone mineral density and a dissociation of bone and muscle measures were age independent, suggesting an additional intrinsic bone defect.

Increased fracture rates in Turner's syndrome: a nationwide questionnaire survey

BACKGROUND AND OBJECTIVES

Reduced bone mineral content (BMC) and bone mineral density (BMD) have previously been reported in Turner's syndrome, although appropriate GH treatment and early induction of puberty seem to permit normal bone mass accumulation. Furthermore, an increased risk of fractures and osteoporosis have been reported in a registry study. The aim of the present study was to further characterize the risk of fractures in TS and to explore risk factors, in a historical follow-up survey based on a self-administered questionnaire.

STUDY GROUPS

The questionnaire was issued to all females with TS (n = 632) in Denmark and to 1888 randomly selected controls (C) matched for age and geographical region. A total of 322 patients (51%) and 1169 controls (62%) returned the questionnaire.

RESULTS

TS women were younger than C (30 years, range: 1-73 years vs. 34 years, range 2-82 years, P < 0.0005), smoked less often (17%vs. 27%, P < 0.0005), and had less frequent spontaneous menstruation (18%vs. 86%, P < 0.0005). In contrast, they used hormonal replacement therapy (HRT) more often (71%vs. 7%, P < 0.0005). The median age at start of HRT was 16 years (range 8-59 years) in TS vs. 42 years (range 12-53 years) in C (P < 0.0005). Above the age of 15 years, 83% of TS and 8% of C used HRT. GH had been used by 37% of TS but only 0.2% of C. Both type 1 and 2 diabetes were increased sevenfold among TS. Altogether, 77 individuals with TS had 109 fractures. The fracture risk was increased in TS [hazard ratio (HR, status) 1.35, confidence interval (CI) 1.04-1.75, P = 0.025]. Time to first fracture was reduced in TS (53 +/- 2 vs. 63 +/- 1; log-rank P = 0.03). Spontaneous menstruation was protective in females above 13 years of age (HR: 0.70, CI 0.54-0.93, P = 0.012). A history of parental fractures increased the risk (HR 1.92, CI 1.62-2.27, P < 0.001). Fractures of the forearm was more frequent among TS (P = 0.02).

CONCLUSION

The present nationwide survey, based on questionnaires, confirms an increased risk of early fractures in TS, especially in those without ovarian function and with a positive family history of fracture and osteoporosis. It thereby emphasizes the need for being vigilant with respect to BMD measurements in these patients.

Marked disproportionality in bone size and mineral, and distinct abnormalities in bone markers and calcitropic hormones in adult turner syndrome: a cross-sectional study

Most women with Turner syndrome (TS) have no gonadal activity and thus lack estrogen. Bone mineral density (BMD) is often reduced, leading to an increased risk of osteoporosis and fractures. However, growth retardation with reduced final height and other endocrine disturbances may compromise interpretation of skeletal measurements. The aim of the present study was to explore skeletal findings, bone metabolism, and calcium homeostasis in TS. Sixty women with TS (age, 37 +/- 9 yr) and 181 normal age-matched female controls were studied. Bone area (A; square centimeters), bone mineral content (BMC; grams), area-adjusted BMD (aBMD; grams/square centimeter), and volumetric BMD (vBMD; grams/cubic centimeter) were measured at lumbar spine, femoral neck, and forearm using dual energy x-ray absorptiometry. Twenty-eight percent had osteopenia, and 23% had osteoporosis, according to World Health Organization criteria. At the lumbar spine, A, BMC, aBMD, and vBMD were reduced by 18, 27, 11, and 6%, respectively; at the femoral neck, A, BMC, and aBMD were reduced by 2, 10, and 8%, respectively, whereas the 9% reduction in vBMD was insignificant (P = 0.07); and in the forearm, A, BMC, and aBMD were reduced by 53, 55, and 9%, respectively. Bone markers indicated an enhanced bone resorption (21 and 23% increase in C-terminal and N-terminal cross-linking telopeptides of type I collagen/creatinine, respectively) with unchanged (osteocalcin, procollagen I N-terminal propeptide) or reduced (54% reduction in bone alkaline phosphatase) bone formation. Plasma levels of calcium and 25-hydroxyvitamin D (26%) were reduced, and PTH levels increased (74%) in TS. IGF-I (30%), IGF binding protein 3 (18%), testosterone (50%), and SHBG (40%) were reduced in TS. In summary, A, BMC, and aBMD were found to be universally reduced in TS, whereas vBMD was slightly reduced in the spine. Increased resorption of bone was present, with normal or blunted bone formation, suggesting uncoupling or imbalance in bone remodeling. Skeletal changes may be induced by chromosome abnormalities or by secondary endocrine or metabolic changes related to a relative estrogen deficiency, testosterone deficiency, reduced IGF-I, low vitamin D status, and secondary hyperparathyroidism.

Clinical and biochemical determinants of bone metabolism and bone mass in adolescent female patients with anorexia nervosa

Among pathologies prevalent in western societies, anorexia nervosa has increased over the last decade. Its effects on bone mass need to be defined, and prognostic factors, either clinical or biochemical, could aid clinicians in individual patient management. To determine which clinical and/or biochemical parameters could be related to bone mass status in adolescent female anorexia nervosa patients, 73 female patients were classified according to different stages of their illness and studied in terms of clinical and biochemical parameters and bone densitometric mineral content at lumbar spine. Patients (age 17.2 +/- 1.7 y, mean +/- SD) with Tanner pubertal stage 5, regular menstruation for more than 3 mo before the onset of secondary amenorrhea, and diagnosed with anorexia nervosa were consecutively studied and classified in three clinical situations: I) active phase (34 patients): undernourished and amenorrheic; II) weight recovered but still amenorrheic (20 patients); III) fully recovered (19 patients). Clinical data were recorded at the time of bone density measurement, concomitant with blood sample extraction for study of IGF-I, IGF-binding protein 3 (IGFBP-3), IGFBP-1, estradiol, sex hormone-binding globulin, dehydroepiandrosterone sulfate, prealbumin, amino-terminal propeptide of procollagen III, osteocalcin, bone alkaline phosphatase, carboxy-terminal propeptide of procollagen I, amino-terminal propeptide of procollagen I, carboxy-terminal telopeptide of collagen I, 25-OH-vitamin D, 1,25(OH)(2)-vitamin D, and parathormone. In addition, a 24-h urine collection was made for cortisol, GH, deoxypyridinoline, amino-terminal telopeptide of collagen I, and calcium and creatinine content analysis. IGF-I, estradiol, and biochemical bone formation markers were higher and IGFBP-1, sex hormone-binding globulin, and biochemical bone resorption markers were lower in the weight-recovered stages (stages II and III) compared with the active phase (stage I). Bone formation markers correlated positively with body mass index SD score and IGF-I, whereas bone resorption markers correlated negatively with body mass index SD score and estradiol. Although no statistically significant differences regarding lumbar spine bone mineral density SD score values were recorded among the three stages of the illness, the proportion of osteopenic patients was clearly lower among stage III patients. The actual bone mineral density was inversely related to the duration of amenorrhea and directly related to duration of postmenarcheal menses before amenorrhea. In addition, a subset of osteopenic patients (five of 19) in the fully clinically recovered group with accelerated bone turnover was identified. Normal circulating estrogen level exposure time predicts actual bone mineral density at lumbar spine in young adolescent anorexia nervosa patients. In addition to psychiatric and nutritional interventions, estrogen-deprivation periods must be shortened to less than 20 mo. Patients remaining osteopenic at full clinical recovery require additional follow-up studies.

Aspects of the treatment of Turner syndrome

Several issues have to be considered when taking care of girls and women with Turner syndrome. During childhood, short stature is the primary concern and treatment with growth hormone (GH) is now widely used, often in conjunction with the androgen, oxandrolone. Recent studies indicate that doses used previously in the treatment of short stature have been too small. Induction of puberty should be performed at an appropriate age with reference to the peers of the patient. In adulthood, female sex hormone substitution should be offered to possibly prevent the increased morbidity seen in Turner syndrome, which consists of increased risk of fractures and osteoporosis, a clustering of diseases like ischaemic heart disease, hypertension, stroke and Type 2 diabetes, the latter entities being involved in the insulin resistance syndrome. Furthermore, hypothyreosis are often seen and the risk of Type 1 diabetes may also be increased. Congenital malformations of the heart are frequently seen in Turner syndrome, possibly increasing the risk of dissecting aorta aneurism. Liver enzymes are often elevated in Turner syndrome and there may be an increased risk of cirrhosis of the liver. Mortality does seem to be increased in Turner syndrome and women with the 'pure' 45,X karyotype do seem to be most severely affected. In the clinical practice of Turner syndrome, a careful monitoring of glucose and bone metabolism, weight, thyroid function and blood pressure should be performed. A cardiovascular risk profile should be determined and the patient informed concerning risks and benefits from sex hormone replacement therapy. Based on the available literature, sex hormone replacement therapy is highly recommended, although at present there are no longitudinal data documenting the long-term positive effect of sex steroid substitution. However, hypogonadism is expected to explain at least part of the decreased lifespan found in Turner syndrome. Since general physicians encounter Turner patients infrequently, it is recommended that the care and treatment of Turner syndrome is centralised.

Early initiation of growth hormone treatment allows age-appropriate estrogen use in Turner's syndrome

Because estrogen (E) accelerates skeletal maturation it can decrease final height attainable with GH therapy in girls with Turner's syndrome (TS). Nonetheless, as age-appropriate E administration does have psychobehavioral benefits for such patients, we asked whether E treatment in TS could occur without adverse impact on final adult height if GH therapy were started at an earlier age. Near adult height (NAH) was assessed in 344 girls with TS, who had received both GH and E and were followed in the National Cooperative Growth Study database. The groups were divided into quartiles based on age at initiation of GH (2-10, 10-12, 12-14, and 14-18 yr). The longest total and E-free period of GH treatment occurred in the girls who had started treatment in the youngest quartile (mean age, 8.2 +/- 1.5 (SD) yr); they were also exposed to E at the youngest age (12.7 +/- 1.6 yr). Although the girls in the youngest group received E at an earlier age, they had a significantly greater increase (1.8 +/- 0.8) in Lyon height SD score at NAH over Lyon predicted adult height than those in the oldest GH-treated group (0.8 +/- 0.6), which first received E at 15.9 +/- 1.3 yr. Multiple linear regression equations for gain in Lyon height SD score and in height (cm) showed greater increments with a longer period of E-free GH therapy. All four GH age groups had the same NAH, but the youngest quartile was youngest at NAH and likely still having more growth potential. Comparable data were found in 127 TS girls with spontaneous puberty. In conclusion, girls with TS starting GH at an early age have a greater gain in Lyon SD score at NAH compared with those starting later, even though they received E at a younger age. If GH therapy were started early, E treatment could be initiated at a younger, more age-appropriate time without compromising adult height.