Fracture rate in women with oestrogen deficiency - Comparison of Turner syndrome and premature ovarian insufficiency

Characterization of Turner Syndrome-associated Diabetes Mellitus

CONTEXT

Diabetes mellitus (DM) risk factors in Turner syndrome (TS) may include autoimmunity, obesity, β-cell dysfunction, genetic predisposition, and insulin resistance (IR).

OBJECTIVE

This work aimed to evaluate glucose tolerance and DM risk factors in adults with TS.

METHODS

A single-center study with 2 phases was conducted to determine the prevalence of DM and to assess DM risk markers comparing women with TS with and without impaired glucose tolerance (IGT). The study took place at a tertiary referral center, University College Hospitals. A total of 106 women with TS (age range, 18-70 years) undergoing annual health surveillance underwent oral glucose tolerance tests (OGTTs), with additional samples for autoimmunity and genetic analysis. Main outcome measures included glucose tolerance, insulin, autoimmune, and single-nucleotide variation (SNV) profile.

RESULTS

OGTT screening showed that among those without a previous DM diagnosis, 72.7% had normal glucose tolerance, 19.5% had IGT, and 7.6% were newly diagnosed with DM. OGTT identified more cases of DM than glycated hemoglobin A1c sampling alone. Women with IGT or DM were older, with higher body mass index and IR. No association was found between autoimmune markers glutamic acid decarboxylase (GAD), islet antigen-2, and zinc transporter 8, risk karyotypes, or selected SNVs and DM. In DM cases, GAD positivity was associated with requirement for insulin therapy. The median age of onset of the diagnosis of DM was 36 years (range, 11-56 years).

CONCLUSION

In the spectrum of DM subtypes, TS-associated DM lies between type 1 and type 2 DM with features of both. Key factors include weight and IR. Assessing C-peptide or GAD antibodies may aid future insulin requirement.

Bone mineral density: Comparison between women under hormone replacement therapy with Turner syndrome or idiopathic premature ovarian insufficiency

CONTEXT

Turner syndrome (TS) is characterized by short stature and premature ovarian insufficiency (POI). The main long-term complication of POI is osteoporosis, which can be prevented by hormone replacement therapy (HRT).

OBJECTIVE

The objective of our study was to compare initial bone mineral density (BMD) and progression between TS and idiopathic POI patients under HRT.

METHODS

A single-center retrospective study was conducted between 1998 and 2018. All women had undergone at least two bone densitometry assessments at least 2 years apart.

RESULTS

Sixty-eight TS patients and 67 idiopathic POI patients were included. Mean age at initial assessment was 27 years (IQR, 21-35.5 years) in TS patients and 31.5 years (IQR, 23-37 years) in idiopathic POI patients (P=0.1). Lumbar and femoral neck BMD were lower in the TS group than in the idiopathic POI group (respectively 0.89g/cm2 versus 0.95g/cm2, P=0.03; 0.70g/cm2 versus 0.77g/cm2, P<0.0001). Mosaic karyotype was associated with better BMD in TS patients while history of growth hormone treatment had no impact on BMD. Over time, a significant gain in vertebral BMD was observed in TS patients versus a loss of BMD in idiopathic POI patients (P=0.0009).

CONCLUSION

TS patients had a lower BMD at baseline than idiopathic POI patients, at both spinal and femoral levels. Over time, on HRT, a significant gain in vertebral BMD was observed in patients with TS, compared with a loss of BMD in patients with idiopathic POI. We hypothesized that earlier initiation and longer duration of HRT played an important role in this finding. Long-term prospective follow-up to assess the incidence of fractures in TS would be useful.

Primary ovarian insufficiency: update on clinical and genetic findings

Primary ovarian insufficiency (POI) is a disorder of insufficient ovarian follicle function before the age of 40 years with an estimated prevalence of 3.7% worldwide. Its relevance is emerging due to the increasing number of women desiring conception late or beyond the third decade of their lives. POI clinical presentation is extremely heterogeneous with a possible exordium as primary amenorrhea due to ovarian dysgenesis or with a secondary amenorrhea due to different congenital or acquired abnormalities. POI significantly impacts non only on the fertility prospect of the affected women but also on their general, psychological, sexual quality of life, and, furthermore, on their long-term bone, cardiovascular, and cognitive health. In several cases the underlying cause of POI remains unknown and, thus, these forms are still classified as idiopathic. However, we now know the age of menopause is an inheritable trait and POI has a strong genetic background. This is confirmed by the existence of several candidate genes, experimental and natural models. The most common genetic contributors to POI are the X chromosome-linked defects. Moreover, the variable expressivity of POI defect suggests it can be considered as a multifactorial or oligogenic defect. Here, we present an updated review on clinical findings and on the principal X-linked and autosomal genes involved in syndromic and non-syndromic forms of POI. We also provide current information on the management of the premature hypoestrogenic state as well as on fertility preservation in subjects at risk of POI.

Factors associated with low bone mineral density in Turner syndrome: a multicenter prospective observational study

Turner syndrome (TS) is associated with a high risk of fracture due to low bone mineral density (BMD). While hypogonadism is known to play a role in decreasing BMD, other factors have not been studied well. Focusing on diet, exercise, and bone metabolism markers, the present, multicentric, prospective, observational study aimed to identify factors contributing to decreased BMD in TS. In total, 48 patients with TS aged between 5 and 49 years comprising a pre-pubertal group (n = 9), a cyclical menstruation group (n = 6), and a hormone replacement therapy (HRT) group (n = 33) were enrolled. The cyclical menstruation group and the HRT group were referred to collectively as the post-pubertal group. The bone mineral apparent density (BMAD) Z-score was higher in the pre-pubertal group than in the post-pubertal group (-0.3 SD vs. -1.8 SD; p = 0.014). Within the post-pubertal group, the median BMAD Z-score was -0.2 SD in the cyclical menstruation group and -2.3 SD in the HRT group (p = 0.016). Spearman's rank correlation revealed no correlation between the BMAD Z-score and bone metabolism markers. No significant relationship was observed between the BMAD Z-score and either the vitamin D sufficiency rate or the step sufficiency rate. A negative correlation was found between BMAD Z-score and serum sclerostin in the pre-pubertal group and serum FSH in the post-pubertal group. In conclusion, the present study found no relationship between the vertebral BMAD Z-score and diet or exercise habits in TS, indicating that estrogen deficiency is the chief reason for low BMD in TS.

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.

Pubertal induction in Turner syndrome without gonadal function: A possibility of earlier, lower-dose estrogen therapy

Delayed and absent puberty and infertility in Turner syndrome (TS) are caused by primary hypogonadism. A majority of patients with TS who are followed at hospitals during childhood will not experience regular menstruation. In fact, almost all patients with TS need estrogen replacement therapy (ERT) before they are young adults. ERT in TS is administered empirically. However, some practical issues concerning puberty induction in TS require clarification, such as how early to start ERT. The present monograph aims to review current pubertal induction therapies for TS without endogenous estrogen production and suggests a new therapeutic approach using a transdermal estradiol patch that mimics incremental increases in circulating, physiological estradiol. Although evidence supporting this approach is still scarce, pubertal induction with earlier, lower-dose estrogen therapy more closely approximates endogenous estradiol secretion.

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.

Secondary Osteoporosis

Osteoporosis is a global public health problem, with fractures contributing to significant morbidity and mortality. Although postmenopausal osteoporosis is most common, up to 30% of postmenopausal women, > 50% of premenopausal women, and between 50% and 80% of men have secondary osteoporosis. Exclusion of secondary causes is important, as treatment of such patients often commences by treating the underlying condition. These are varied but often neglected, ranging from endocrine to chronic inflammatory and genetic conditions. General screening is recommended for all patients with osteoporosis, with advanced investigations reserved for premenopausal women and men aged < 50 years, for older patients in whom classical risk factors for osteoporosis are absent, and for all patients with the lowest bone mass (Z-score ≤ -2). The response of secondary osteoporosis to conventional anti-osteoporosis therapy may be inadequate if the underlying condition is unrecognized and untreated. Bone densitometry, using dual-energy x-ray absorptiometry, may underestimate fracture risk in some chronic diseases, including glucocorticoid-induced osteoporosis, type 2 diabetes, and obesity, and may overestimate fracture risk in others (eg, Turner syndrome). FRAX and trabecular bone score may provide additional information regarding fracture risk in secondary osteoporosis, but their use is limited to adults aged ≥ 40 years and ≥ 50 years, respectively. In addition, FRAX requires adjustment in some chronic conditions, such as glucocorticoid use, type 2 diabetes, and HIV. In most conditions, evidence for antiresorptive or anabolic therapy is limited to increases in bone mass. Current osteoporosis management guidelines also neglect secondary osteoporosis and these existing evidence gaps are discussed.

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.

New insights into the diagnosis and management of bone health in premature ovarian insufficiency

Premature ovarian insufficiency (POI), defined as a loss of ovarian function before the age of 40 years, is a life-changing diagnosis that has numerous long-term consequences. Musculoskeletal complications, including osteoporosis and fractures, are a key concern for women with POI. The risk of bone loss is influenced by the underlying etiology of POI, and the degree and duration of estrogen deficiency. A decline in muscle mass as a result of estrogen and androgen deficiency may contribute to skeletal fragility, but has not been examined in women with POI. This article aims to review musculoskeletal health in POI; summarize the traditional and novel modalities available to screen for skeletal fragility and muscle dysfunction; and provide updated evidence for available management strategies.

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.