Turner Syndrome, Insulin Sensitivity and Growth Hormone Treatment

Hyperglycemia in Turner syndrome: Impact, mechanisms, and areas for future research

Turner syndrome (TS) is a common chromosomal disorder resulting from complete or partial absence of the second sex chromosome. Hyperglycemia, ranging from impaired glucose tolerance (IGT) to diabetes mellitus (DM), is common in TS. DM in individuals with TS is associated with an 11-fold excess in mortality. The reasons for the high prevalence of hyperglycemia in TS are not well understood even though this aspect of TS was initially reported almost 60 years ago. Karyotype, as a proxy for X chromosome (Xchr) gene dosage, has been associated with DM risk in TS - however, no specific Xchr genes or loci have been implicated in the TS hyperglycemia phenotype. The molecular genetic study of TS-related phenotypes is hampered by inability to design analyses based on familial segregation, as TS is a non-heritable genetic disorder. Mechanistic studies are confounded by a lack of adequate TS animal models, small and heterogenous study populations, and the use of medications that alter carbohydrate metabolism in the management of TS. This review summarizes and assesses existing data related to the physiological and genetic mechanisms hypothesized to underlie hyperglycemia in TS, concluding that insulin deficiency is an early defect intrinsic to TS that results in hyperglycemia. Diagnostic criteria and therapeutic options for treatment of hyperglycemia in TS are presented, while emphasizing the pitfalls and complexities of studying glucose metabolism and diagnosing hyperglycemia in the TS population.

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.

Cardiovascular considerations in management of patients with Turner syndrome

Turner syndrome (TS) is a chromosomal disorder that affects 25-50 per 100,000 live born females. Patients with TS face a heavy burden of cardiovascular disease (congenital and acquired) with an increased risk of mortality and morbidity compared to the general population. Cardiovascular diseases are a major cause of death in females with TS. Approximately 50% of TS patients have a congenital heart abnormality, with a high incidence of bicuspid aortic valve (BAV), coarctation of the aorta (CoA) and generalised arteriopathy. Frequently, females with TS have systemic hypertension, which is also a risk factor for progressive cardiac dysfunction and aortopathy. This paper aims to provide an overview of the cardiovascular assessment, management and follow up strategies in this high-risk population of TS patients.

Increased Prevalence of Beta-Cell Dysfunction despite Normal HbA1c in Youth and Young Adults with Turner Syndrome

INTRODUCTION

Adult women with Turner syndrome (TS) have a high prevalence of diabetes and β-cell dysfunction that increases morbidity and mortality, but it is unknown if there is β-cell dysfunction present in youth with TS. This study aimed to determine the prevalence of β-cell dysfunction in youth with TS and the impact of traditional therapies on insulin sensitivity (SI) and insulin secretion.

METHODS

Cross-sectional, observational study recruited 60 girls with TS and 60 healthy controls (HC) matched on pubertal status. Each subject had a history, physical exam, and oral glucose tolerance test (OGTT). Oral glucose and c-peptide minimal modeling was used to determine β-cell function.

RESULTS

Twenty-one TS girls (35%) met criteria for prediabetes. Impaired fasting glucose was present in 18% of girls with TS and 3% HC (p value = 0.02). Impaired glucose tolerance was present in 23% of TS girls and 0% HC (p value <0.001). The hemoglobin A1c was not different between TS and HC (median 5%, p = 0.42). Youth with TS had significant reductions in SI, β-cell responsivity (Φ), and disposition index (DI) compared to HC. These differences remained significant when controlling for body mass index z-score (p values: 0.0006, 0.002, <0.0001 for SI, Φ total, DI, respectively).

CONCLUSIONS

β-Cell dysfunction is present in youth with TS compared to controls. The presence of both reduced insulin secretion and SI suggest a unique TS-related glycemic phenotype. Based on the data from this study, we strongly suggest that providers employ serial OGTT to screen for glucose abnormalities in TS youth.

Insulin Sensitivity and Pancreatic β-Cell Function in Ecuadorian Women With Turner Syndrome

Objective: To assess insulin sensitivity and pancreatic β-cell function in an adult population of Ecuadorian individuals with Turner syndrome (TS). Design and Methods: This was a cross-sectional correlational study conducted in TS subjects (>20 years old; n = 38). A standard 2-h oral glucose tolerance test was performed in both women with TS and the reference group. Glucose, lipids, insulin, and C-peptide concentrations were measured. Homeostasis Model Assessment (HOMA) of Insulin Resistance, Quantitative Insulin Sensitivity Check Index, McAuley, Matsuda, and Belfiore indices were calculated to evaluate the degree of insulin resistance (IR). The pancreatic β-cell function was assessed using HOMA-β, basal C-Peptide Index (CPI), and CPII at 120'. Results: A higher prevalence of impaired glucose tolerance was found in TS subjects compared with the reference group. Although significant differences were found for glucose concentrations at 60' and 120' (but not at 0'), only the baseline insulin concentrations differed significantly between the two groups. The values of the IR indices were statistically different between study and reference groups. A significant number of TS subjects diagnosed with IR were differently classified according to the index applied. The concentrations of C-peptide at 0' and 120' of TS subjects were similar to those of the control group. In contrast, the CPI and CPII values in the study group were significantly lower than those in the control group. Conclusion: It is impossible to select the best surrogate method for the assessment of IR in women with TS. The CPI and CPII values could be preferable to other indices to assess the pancreatic β-cell function in TS subjects. Our findings suggest that IR and pancreatic β-cell dysfunction could be independent events in women with TS, and both conditions seem to be caused by the disease per se. Our results imply that early screening and intervention for TS would be therapeutic for TS women.

Glucose Metabolism in Turner Syndrome

Turner syndrome (TS) is one of the most common female chromosomal disorders. The condition is caused by complete or partial loss of a single X chromosome. Adult patients with TS have a high prevalence of diabetes mellitus (DM). Deranged glucose metabolism in this population seems to be genetically triggered. The traditional risk factors for DM in the general population may not play a major role in the pathogenesis of DM in patients with TS. This review focuses on the latest research studies pertaining to abnormalities of glucose metabolism in TS. We extensively review the available evidence pertaining to the influence of insulin secretion and sensitivity, obesity, autoimmunity, lifestyle, growth hormone, and sex hormone replacement therapy on the occurrence of DM in these patients.

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.

Cardiometabolic and vascular risks in young and adolescent girls with Turner syndrome

BACKGROUND

Turner syndrome (TS) is the most common chromosomal abnormality in females and is associated with several co-morbidities. It commonly results from X monosomy which is diagnosed on a 30 cell karyotype. Congenital heart disease is a clinical feature in 30% of cases. It is becoming evident that TS patients have an increased risk of cardiovascular and cerebrovascular diseases.

SCOPE OF REVIEW

This review provides a detailed overview of the literature surrounding cardiometabolic health in childhood and adolescent TS. In addition, the review also summarises the current data on the impact of growth hormone (GH) therapy on cardiometabolic risk in paediatric TS patients.

MAJOR CONCLUSIONS

Current epidemiological evidence suggests that young women and girls with TS have unfavourable cardiometabolic risk factors which predispose them to adverse cardiac and cerebrovascular outcomes in young adulthood. It remains unclear whether this risk is the result of unidentified factors which are intrinsic to TS, or whether modifiable risk factors (obesity, hypertension, hyperglycaemia) are contributing to this risk.

GENERAL SIGNIFICANCE

From a clinical perspective, this review highlights the importance of regular screening and pro-active management of cardiometabolic risk from childhood in TS cohorts and that future research should aim to address whether modification of these variables at a young age can alter the disease process and atherosclerotic outcomes in adulthood.

Insulin resistance in adolescents with Turner syndrome is comparable to obese peers, but the overall metabolic risk is lower due to unknown mechanism

PURPOSE

An increased risk of insulin resistance, hypertension and liver dysfunction is related to obesity (Ob), but may be also present in normal-weight Turner syndrome (TS) patients. The aim of the study was to compare metabolic risk in adolescents with TS and Ob.

METHODS

The study included 21 non-obese with TS (all receiving human recombinant growth hormone, 17/21 estrogen/estrogen-progesterone), and 21 age-matched Ob girls (mean age 13.9 years). Glucose and serum insulin levels were assessed fasting and in 120' of standard oral glucose tolerance test. Levels of triglycerides (TG), total cholesterol (TC), low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol, alanine aminotransferase (ALT), FGF19, FGF21 and FGF23 levels were measured fasting.

RESULTS

Mean BMI SDS was significantly lower in TS patients (0.1 vs 4.8 SD, p < 0.001). The mean systolic and diastolic blood pressure was significantly lower in TS patients (102.6 vs 124.2 mmHg, p < 0.001 and 67.1 vs 76.5 mmHg, p = 0.02). There were no differences concerning mean fasting, and post-load glucose (4.5 vs 4.3, 5.1 vs 5.8 mmol/L), and insulin (14.97 vs 17.19 and 69.3 vs 98.78 μIU/mL) levels, HOMA-IR (3.02 vs 3.4), TC (4.05 vs 4.4 mmol/L), TG (1.25 vs 1.37 mmol/L), ALT (26.9 vs 28.3 IU/L), FGF19 (232.8 vs 182.7 pg/mL), and FGF23 (12.3 vs 17.5 pg/mL) levels. Mean LDL (2.05 vs 2.7 mmol/L, p = 0.003) and FGF21 (293.9 vs 514.7 pg/mL, p = 0.007) levels were significantly lower, and HDL (1.7 vs 1.2 mmol/L, p < 0.001) level higher in TS group.

CONCLUSIONS

Insulin resistance in adolescents with TS on growth hormone treatment is comparable to Ob patients, but overall metabolic risk factors seem to be lower.

The influence of hormonal replacement and growth hormone treatment on the lipids in Turner syndrome

AIM

Women with Turner syndrome (TS) have a risk of developing cardiovascular diseases. We assessed the lipid and carbohydrate metabolism in TS-women in the context of current hormone replacement therapy (HRT) and growth hormone (GH) treatment during childhood.

METHODS

The information were collected from medical documentation and anamnesis of 165 TS-women (24.9 ± 7.7 yr) between 1995 and 2011. The patients underwent a pituitary-gonadal axis assessment together with measurements of total cholesterol (TC), high- (HDL) and low- (LDL) density lipoproteins, triglycerides (TG), and glucose levels.

RESULTS

Only 58% of women were using HRT. No differences were found in the levels of the lipid components and glucose in women who were undergoing HRT compared to those without it. Compared to TS-women without (n  =  113), prior GH treatment in 34 TS-women positively influenced the lipid parameters: TC 5.0 ± 1.1 versus 4.6 ± 0.9 mmol/l (p = 0.03), HDL 1.5 ± 0.5 versus 1.4 ± 0.4 mmol/l (p > 0.05), LDL 3.3 ± 0.9 versus 2.9 ± 0.7 mmol/l (p = 0.03), and TG 1.1 ± 0.6 versus 0.8 ± 0.3 g/l (p = 0.009), respectively.

CONCLUSIONS

(1) HRT does not affect lipid metabolism in TS-women. (2) The use of GH in TS-children favorably influences their lipid profile in adulthood.

Transitions in endocrinology: treatment of Turner's syndrome during transition

Transition in health care for young patients with Turner's syndrome (TS) should be perceived as a staged but uninterrupted process starting in adolescence and moving into adulthood. As a condition associated with high risk of short stature, cardiovascular diseases, ovarian failure, hearing loss and hypothyroidism, TS requires the attention of a multidisciplinary team. In this review paper, we systematically searched the relevant literature from the last decade to discuss the array of problems faced by TS patients and to outline their optimal management during the time of transfer to adult service. The literature search identified 233 potentially relevant articles of which 114 were analysed. The analysis confirmed that all medical problems present during childhood should also be followed in adult life. Additionally, screening for hypertension, diabetes mellitus, dyslipidaemia, and osteoporosis is needed. After discharge from the paediatric clinic, there is still a long way to go.

Turner syndrome and metabolic derangements: another example of fetal programming

BACKGROUND AND AIM

Turner syndrome (TS) patients have an increased risk of weight gain and metabolic syndrome. To date, it is unknown what factors are involved in this metabolic process, even though it is recognized that TS patients are frequently born small-for-gestational age. The aim of this study was to evaluate the correlation between lipid and glucose profiles with being overweight and birth weight and length in TS patients.

STUDY DESIGN

This was a cross-sectional study.

SUBJECTS AND OUTCOME MEASURES

Serum glucose, insulin (HOMA-IR), total cholesterol, and triglycerides were measured in 64 patients with TS. Data regarding birth weight and length and current body mass index (BMI) were also evaluated.

RESULTS

Total cholesterol showed a significant negative correlation with birth weight and a positive correlation with BMI; triglycerides showed significant negative correlation with birth weight and length and a positive correlation with BMI; and HOMA-IR showed a significant negative correlation with birth weight and length. Low birth weight and a high BMI were predictive for 28% of total cholesterol and triglycerides; and low birth weight for 22% of HOMA-IR.

CONCLUSIONS

Lipid profile was correlated with a high current BMI and low birth weight and length in TS patients and glucose profile only with low birth weight. Thus far, growth retardation may play a role in metabolic derangements in this group of patients, being considered another example of fetal programming.

Turner Syndrome

Turner syndrome is a neurogenetic disorder characterized by partial or complete monosomy-X. It is associated with certain physical and medical features, including estrogen deficiency, short stature, and increased risk for several diseases, with cardiac conditions being among the most serious. The cognitive-behavioral phenotype associated with the syndrome includes strengths in verbal domains with impairments in visuospatial, executive function, and emotion processing. Less is known regarding psychosocial and psychiatric functioning in Turner syndrome, but essential aspects of psychotherapeutic treatment plans are suggested. Future investigations should include continued genetic studies and determination of candidate genes for physical and cognitive features. Multimodal, interdisciplinary studies are essential for identifying optimal, syndrome-specific interventions for improving the lives of individuals who have Turner syndrome.

Spinal cord stimulation in the treatment of post-stroke patients: current state and future directions

A decrease in cerebral blood flow (CBF) and brain metabolic activity are well-known complications of stroke. Spinal cord stimulation (SCS) is successfully being used for the treatment of several low-perfusion syndromes. The aim of this chapter is to describe the data that support the effect of SCS on CBF and the use of SCS in the treatment of stroke and cerebral low perfusion syndromes. In addition, we present our relevant studies. Since April 1995, we have assessed 49 non-stroke patients. The following parameters were measured pre- and post-stroke: (1) CBF in healthy contralateral tissue by single photon emission computed tomography (SPECT), (2) systolic and diastolic velocity in the middle cerebral artery (MCA) by transcranial Doppler, (3) blood flow quantification in the common carotid artery (CCA) by color Doppler, and (4) glucose metabolism in healthy contralateral tissue by positron emission tomography (PET). Our results showed that during cervical SCS there was a significant (p < 0.001) increase in systolic (> or =21%) and diastolic (>26%) velocity in the MCA, and CCA blood flow (> or =51%) as well as glucose metabolism (44%). We concluded that cervical SCS (cSCS) can modify CBF and brain metabolism. Its potential role in the management of stroke and low-perfusion syndromes is further investigated by experimental studies and reports describing clinical experience. Appropriate clinical trials are warranted.