Bulent O Yildiz

Hacettepe University · Department of Endocrinology

Aging is associated with several changes in the endocrine system, possibly due to altering hormone secretion patterns, disordered feedback-feedforward networks, low sensitivity of tissues to hormone action, and reduced bioavailability of hormones. Overall, aging-related hormonal changes appear to worsen the frailty of aging, as they are associated...

Background There is a lack of data on the prevalence of PCOS and its phenotype in many geographic regions. Siberia is a unique region of the Russian Federation with a multi-raced population living in similar geographic and socio-economic conditions for centuries. Therefore, we considered this population optimal for epidemiological research. Object...

Purpose of review: The aim of this review is to understand how anti-Müllerian hormone (AMH) contributes to ovulatory dysfunction in polycystic ovarian syndrome (PCOS). Recent findings: In the last few years, new findings have emerged on AMH and its role on the central nervous system causing ovulatory dysfunction. Summary: Anovulation is a prom...

The multifaceted interaction between coronavirus disease 2019 (COVID-19) and the endocrine system has been a major area of scientific research over the past two years. While common endocrine/metabolic disorders such as obesity and diabetes have been recognized among significant risk factors for COVID-19 severity, several endocrine organs were ident...

Introduction: Polycystic ovary syndrome (PCOS) is a common hormonal, metabolic, and reproductive disorder with a heterogeneous phenotype. As the exact etiology of PCOS is still unclear, available pharmacotherapies are mostly directed towards alleviating symptoms and associated metabolic abnormalities. Areas covered: Herein, we present an overvie...

Polycystic ovary syndrome (PCOS) is one of the most common reproductive health problems of women, causing irregular periods and potential infertility amongst other challenging symptoms. Effective treatment remains a significant challenge and is largely achieved through hormonal medication and lifestyle changes. This third edition covers the aetiolo...

Coronavirus Disease 2019 (COVID-19) is characterized with a wide range of clinical presentations from asymptomatic to severe disease. In patients with severe disease, the main causes of mortality have been acute respiratory distress syndrome, cytokine storm and thrombotic events. Although all factors that may be associated with disease severity are...

Purpose COVID-19 pandemic has far-reaching psychosocial implications for chronic health conditions. We aimed to investigate whether COVID-19 associated social isolation affects lifestyle and weight control in women with polycystic ovary syndrome (PCOS). Methods We conducted an online survey involving 232 women with PCOS and 157 healthy controls on...

Metabolic dysfunction, although not included in the diagnostic criteria, is very common in polycystic ovary syndrome (PCOS), especially in overweight/obese patients. Because metabolic disorders may not be as noticeable and/or disturbing as the other features of PCOS, it is important for physicians to inform and evaluate the patients in this regard....

Understanding of gustatory coding helps to predict, and perhaps even modulate the ingestive decision circuitry, especially when eating behaviour becomes dysfunctional. Preclinical research demonstrated that glucagon like peptide 1 (GLP-1) is locally synthesized in taste bud cells in the tongue and that GLP-1 receptor exists on the gustatory nerves...

The diagnosis of polycystic ovary syndrome (PCOS) remains challenging due to limited data regarding normative cut-offs for the diagnostic features in different subpopulations. We aim to conduct a systematic review, build a comprehensive repository of de-identified individual participant data (IPD), and define normative ranges and diagnostic cut-off...

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women of reproductive age that is associated with eating disorders and disordered eating. No data is available regarding taste function in women with PCOS. The aim of this study was to assess taste function and eating behavior in patients with PCOS compared to healthy women a...

Sport is historically designated by the binary categorization of male and female that conflicts with modern society. Sport’s governing bodies should consider reviewing rules determining the eligibility of athletes in the female category as there may be lasting advantages of previously high testosterone concentrations for transwomen athletes and cur...

A correction to this paper has been published: https://doi.org/10.1007/s40279-021-01467-0

Polycystic ovary syndrome (PCOS) is a common hormonal, metabolic and reproductive disorder. Women with PCOS at reproductive age have increased risk and prevalence of prediabetes and diabetes and have multiple risk factors for cardiometabolic disease and other comorbidities such as obstructive sleep apnoea, endometrial cancer and mood disorders, whi...

Hirsutism is defined as excess growth of body or facial terminal (coarse) hair in females, in a male-like pattern. In addition to its possible association with conditions such as polycystic ovary syndrome (PCOS) and the associated risk of cardiometabolic diseases and infertility, hirsutism has a significant negative impact on a woman’s self-esteem...

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder affecting 6–10% of the reproductive age women worldwide. It is a complex multifactorial syndrome with polygenic inheritance and epigenetic alterations. PCOS is characterized by clinical and/or biochemical hyperandrogenism (HA), ovulatory dysfunction (OD), and polycystic ovarian...

obesity represents a major health problem worldwide and is associated with increased prevalence of numerous health-related conditions, including diabetes, hypertension, cardiovascular disease, some forms of cancer and musculoskeletal disorders, among others. Studies that have examined the impact of physical exercise combined with energy restriction...

Changes that COVID-19 induced in endocrine daily practice as well as the role of endocrine and metabolic comorbidities in COVID-19 outcomes were among the striking features of this last year. Aim of this statement is to illustrate the major characteristics of the response of European endocrinologists to the pandemic including the disclosure of the...

The hypoestrogenic period after menopause and associated metabolic imbalance might facilitate the onset of non-alcoholic fatty liver disease (NAFLD) and its progression. The prevalence of NAFLD increases in patients experiencing premature ovarian insufficiency, as well as surgical or natural menopause. The postmenopausal period is characterized by...

Background: Transgender people using hormone treatment require lifelong medical care. Although cross-sex hormone treatment (CSHT) is usually considered safe, serious adverse events may occur. Here we report a case of deep vein thrombosis associated with estradiol treatment in an otherwise healthy young transgender woman. Case Presentation: A 21-yea...

Polycystic ovary syndrome (PCOS) is a complex disorder associated with obesity, sleep apnea, and disordered eating. We aimed to assess whether COVID19 related social isolation affects lifestyle and weight control in women with PCOS. We performed an online survey including 232 women with PCOS and 157 healthy controls on isolation characteristics, we...

PurposeThe current study aimed to determine the publication outcome of abstracts presented at the 16th European Congress of Endocrinology (ECE 2014).Methods All presentations were collected with the web scraping - Python coding from the official website and converted into Google Scholar and PubMed search links with coding. A particular interface wa...

BackgroundCOVID-19 has completely changed our daily clinical practice as well as our social relations. Many organs and biological systems are involved in SARS-Cov-2 infection, either due to direct virus-induced damage or to indirect effects that can have systemic consequences. Endocrine system is not only an exception but its involvement in COVID-1...

Polycystic ovary syndrome (PCOS) is a common endocrine disorder in reproductive-aged women, characterized by hyperandrogenism, oligo/anovulation, and polycystic ovarian morphology. Combined oral contraceptives (COCs), along with lifestyle modifications, represent the first-line medical treatment for the long-term management of PCOS. Containing low...

Introduction Polycystic ovary syndrome (PCOS) is the most common endocrine disorder of reproductive aged women. Overweight and obesity commonly accompany the syndrome at the clinic and are significant concerns for women with PCOS. Areas covered Herein, we provide an overview of the relevant literature on weight management strategies in women with...

Background and Objective Obesity has been reported as a risk factor for adverse outcomes in COVID-19. However, available studies presenting data on obesity prevalence in patients with COVID-19 have conflicting results. The objective of this systematic review and meta-analysis is to evaluate the prevalence of obesity in these patients and to stratif...

This systematic review aimed to assess variations on the clinical presentation and treatment outcomes of patients with PCOS belonging to different ethnicities. A search was performed for studies comparing various clinical aspects of PCOS in two or more different ethnic groups. After the screening of 2264 studies, 35 articles were included in the fi...

Obesity represents a major health problem worldwide and is associated with increased prevalance of numerous health-related conditions, including diabetes, hypertension, cardiovascular disease, some forms of cancer and musculoskeletal disorders among others. Studies that have examined the impact of physical exercise combined with energy restriction...

Context Polycystic ovary syndrome is the most common endocrine disorder of women in reproductive age and is associated with reproductive, endocrine, metabolic, cardiovascular and psychological outcomes. All these disorders are thought to be affected by central mechanisms which could be a major contributor in pathogenesis of PCOS. Evidence Acquisit...

Background: Limited available animal and human data suggest an association between dysbiosis of gut microbiota and PCOS. We aimed to determine whether gut microbiota in lean women with PCOS shows any alterations compared to healthy women. Materials and methods: Twenty-four lean patients with PCOS phenotype A according to the Rotterdam 2003 diagn...

Context Polycystic ovary syndrome (PCOS) is a common and complex endocrine disorder. Emerging animal and human data point out to various changes in microbiota that could be linked with the syndrome. However, the effects of therapeutic approaches on gut microbial composition in women with PCOS remain unknown. Objective We aimed to assess whether gu...

Research Question This study aims to investigate potential differences between lean women with and without PCOS regarding fat content in liver, vertebrae, paraspinal muscles, pancreas, subcutaneous (SCAT) and visceral adipose tissue (VAT) areas by using magnetic resonance imaging – proton density fat fraction (MRI-PDFF), a novel, noninvasive, opera...

Polycystic ovary syndrome (PCOS) is a common endocrine disorder with heterogenous clinical manifestations. The evidence indicates that PCOS is associated with long-term health risks including type 2 diabetes, metabolic syndrome, obstructive sleep apnea, endometrial cancer, and mood disorders. Although cardiometabolic risk factors are more common am...

Polycystic ovary syndrome (PCOS) is the most prevalent endocrine-metabolic disorder affecting 6–10% of reproductive-aged women worldwide. The features of PCOS are clinical and/or biochemical hyperandrogenism (HA), ovulatory dysfunction (OD) and polycystic ovarian morphology (PCOM). There are three different diagnostic criteria sets and the syndrome...

IntroductionTargeting better glycated hemoglobin (HbA1c) and blood pressure (BP) goals may endanger older adults with type 2 diabetes mellitus (T2DM). Overtreatment of T2DM and hypertension is a trending issue, although undertreatment is still common. We investigated the rates and predictors of overtreatment and undertreatment of glycemia and BP in...

Introduction: Polycystic ovary syndrome (PCOS) is a common endocrine disorder with heterogenous clinical manifestations. Current evidence suggests that women with PCOS exhibit an unfavorable metabolic profile which may pose them at increased risk for cardiovascular events later in life. Areas covered: Herein, we present a review of the existing lit...

Study question: What are the best practices for undertaking epidemiologic and phenotypic studies in polycystic ovary syndrome (PCOS)? Summary answer: Best practices for the undertaking of epidemiologic and phenotypic studies in PCOS are outlined. What is known already: Currently methodologies used for studies of PCOS epidemiology and phenotype...

Unwanted sexual hair growth has a considerable negative impact on a woman's self-esteem and quality of life. Excessive growth of terminal hair in women in a man-like pattern is defined as hirsutism and affects up to 1 in 7 women. Androgens secreted by the ovary and adrenal are the main regulator of physiological and pathological alterations of skin...

Purpose Polycystic ovary syndrome (PCOS) is the most common endocrine disorder of women of reproductive age. The aim of the current study was to assess muscle mechanical function in PCOS and its relationship with hormonal and metabolic features of the syndrome. Methods The study included 44 women with PCOS, all having clinical or biochemical hyper...

Context: Polycystic ovary syndrome (PCOS) is associated with an increased cardiometabolic risk that might not necessarily translate into adverse cardiovascular outcome later in life. Recently, alterations in gut microbial composition have been reported in the syndrome. Microbiota dependent metabolite trimethylamine N-oxide (TMAO) and its precursor...

PURPOSE: Polycystic ovary syndrome (PCOS) is the most common endocrine disorder of women of reproductive age. The aim of the current study was to assess muscle mechanical function in PCOS and its relationship with hormonal and metabolic features of the syndrome. METHODS: The study included 44 women with PCOS, all having clinical or biochemical hyp...

Research question: What are the potential differences between lean women with and without polycystic ovary syndrome (PCOS) in fat content in liver, vertebrae, paraspinal muscles, pancreas, subcutaneous (SCAT) and visceral adipose tissue (VAT)? Magnetic resonance imaging proton density fat fraction (PDFF) was used to establish these differences. Thi...

Research question: Is anti-Müllerian hormone (AMH) a valid tool to diagnose polycystic ovary syndrome (PCOS) according to different subsets of criteria among an unselected group of women? Design: In this cross-sectional study, AMH concentrations were measured in an unselected group of women. The ability of AMH to diagnose PCOS according to Natio...

Background: Metabolic syndrome (MetS) is an important public health concern associated with an increased risk for cardiovascular disease and type 2 diabetes. Despite its global significance, the prevalence of MetS in Azerbaijan is unknown. The purpose of this study was to examine the prevalence of MetS and its relation to physical activity (PA) an...

Purpose: To provide practice recommendations for the diagnosis and management of hypoparathyroidism in adults Methods: Key questions pertaining to the diagnosis and management of hypoparathyroidism were addressed following a literature review. We searched PubMed, MEDLINE, EMBASE and Cochrane databases from January 2000 to March 2018 using keywords...

Aim: Prevalence rates of gestational diabetes mellitus (GDM) show considerable variation among different countries and regions of the world. The primary aim of this study was to determine the nationwide prevalence and predictors of GDM in Turkey. Methods: We conducted prospective nationwide screening among pregnant women. Between August 2016 and...

The metabolic syndrome (MetS) comprises individual components including central obesity, insulin resistance, dyslipidaemia and hypertension and it is associated with an increased risk of cardiovascular disease (CVD) and type 2 diabetes mellitus (T2DM). The menopause per se increases the incidence of MetS in aging women. The effect(s) of menopause o...

Background: Currently, exogenous hormone replacement is used in many men with hypogonadism without clear organic cause. This study examines the contribution of modifiable health behaviors, i.e., physical activity and weight control, to the maintenance of testosterone levels with aging. Methods: In a cross-sectional study of 2994 healthy men aged 50...

Study Question What is the recommended assessment and management of women with polycystic ovary syndrome (PCOS), based on the best available evidence, clinical expertise, and consumer preference? Summary Answer International evidence‐based guidelines including 166 recommendations and practice points, addressed prioritized questions to promote cons...

Study question: What is the recommended assessment and management of women with polycystic ovary syndrome (PCOS), based on the best available evidence, clinical expertise and consumer preference? Summary answer: International evidence-based guidelines, including 166 recommendations and practice points, addressed prioritized questions to promote...

Study question: What is the recommended assessment and management of women with polycystic ovary syndrome (PCOS), based on the best available evidence, clinical expertise, and consumer preference? Summary answer: International evidence-based guidelines including 166 recommendations and practice points, addressed prioritized questions to promote...

Objective(s): To analyze whether first-degree relatives (FDR) of patients with polysystic ovary syndrome (PCOS) have an increased risk of insulin resistance and glucose intolerance. Design: Systematic review and meta-analysis. Setting: None. Patient(s): Parents and siblings of women with and without PCOS. Intervention(s): Search of PubMed...

Objective: To formulate clinical consensus recommendations for screening depression, anxiety, health-related quality of life (HRQoL), and disordered eating symptoms in women with polycystic ovary syndrome (PCOS) and review prevalence based on phenotypes and ethnicity, changes over time, etiology, and impact of treatment. Design: Systematic revie...

Objective: To provide an evidence-based assessment of metabolic syndrome, hypertension, and hyperlipidemia in first-degree relatives of women with polycystic ovary syndrome (PCOS). Design: Systematic review and meta-analysis. Setting: Not applicable. Patient(s): Mothers, fathers, sisters, and brothers of women with and without PCOS. Interve...

Background/aim: Isotretinoin, the drug of choice for severe acne, might be associated with a decrease in insulin sensitivity. Adiponectin is an adipose tissue-derived protein that increases insulin sensitivity. In this study, we aimed to investigate adiponectin levels in postadolescent severe acne and the effect of isotretinoin on adiponectin leve...

This paper represents an international collaboration of paediatric endocrine and other societies (listed in the Appendix) under the International Consortium of Paediatric Endocrinology (ICPE) aiming to improve worldwide care of adolescent girls with polycystic ovary syndrome (PCOS)1. The manuscript examines pathophysiology and guidelines for the di...

Background and objective: Polycystic ovary syndrome (PCOS) has been reported to be associated with the development of obstructive sleep apnea (OSA). The objective of this meta-analysis is to assess the relationship between PCOS and OSA. Methods: A literature search was conducted to identify studies linking PCOS with the risk of OSA. Studies in w...

Purpose: To detect differences in global brain volumes and identify relations between brain volume and appetite-related hormones in women with polycystic ovary syndrome (PCOS) compared to body mass index-matched controls. Methods: Forty subjects participated in this study. Cranial magnetic resonance imaging and measurements of fasting ghrelin, l...

STUDY QUESTION What is the reported overall prevalence of polycystic ovary syndrome (PCOS) according to the criteria of the National Institutes of Health (NIH), Rotterdam or the Androgen Excess and PCOS Society (AE-PCOS Society)? SUMMARY ANSWER The reported overall prevalence of PCOS (95% CI) according to diagnostic criteria of the NIH, Rotterdam...

Polycystic ovary syndrome (PCOS) affects 5–20% of women of reproductive age worldwide. The condition is characterized by hyperandrogenism, ovulatory dysfunction and polycystic ovarian morphology (PCOM) — with excessive androgen production by the ovaries being a key feature of PCOS. Metabolic dysfunction characterized by insulin resistance and compe...

Background: Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in reproductive aged women and is characterized by two of the following three features: oligoovulation or anovulation, clinical and/or biochemical signs of hyperandrogenism, or polycystic ovaries. Summary: It has been demonstrated that PCOS includes a complex numb...

Polycystic ovary syndrome (PCOS) is a common and complex endocrine disorder, often accompanied and complicated by insulin resistance, glucose intolerance and obesity. Gut, brain and metabolism are highly related with each other in obesity and diabetes as well as in PCOS. Central nervous system regulates food intake through complex interactions of h...

Oral contraceptives are the mainstay of long-term PCOS treatment, but have potential adverse cardiometabolic effects. In a randomized controlled trial comparing oral contraceptive use and structured exercise in women with PCOS and overweight on a calorie-restricted diet, androgen excess was ameliorated with oral contraceptive use and structured exe...

Polycystic ovary syndrome (PCOS) is a common and complex genetic disorder that develops under varying degrees of hyperandrogenemic and hyperinsulinemic conditions that cause phenotypic variability ranging from mild hirsutism to anovulation and infertility. In addition to increased risk of reproductive disability, PCOS is associated with metabolic d...

Periodontal disease is a chronic inflammatory disease of the jaws and is more prevalent in obesity. Local and systemic oxidative stress may be an early link between periodontal disease and obesity. The primary aim of this study was to detect whether increased periodontal disease susceptibility in obese individuals is associated with local and syste...

Insulin therapy is often associated with adverse weight gain. This is due, at least in part, to changes in energy balance and insulin's anabolic effects. Adverse weight gain increases the risk of poor macrovascular outcomes in people with diabetes and should therefore be mitigated if possible. Clinical studies have shown that insulin detemir, a bas...

BACKGROUND: Little is known about the role of advanced glycation end products (AGEs) and their receptor (RAGE) in diabetic cardiovascular complications. Therefore, we aimed to evaluate the association of serum soluble RAGE (sRAGE) levels and left ventricular diastolic dysfunction in patients with type 2 diabetes. METHODS: Our study consisted of 40...

Polycystic ovary syndrome (PCOS) is a common reproductive and metabolic disorder. Patients with PCOS present with clinical signs of androgen excess (ie, hirsutism and acne), menstrual irregularities, and infertility. Combined oral contraceptive (OC) pills are the first-line medical therapy for the long-term management of PCOS. Containing a combinat...

Background Increased adrenocortical production appears to be associated with acne and hirsutism in acne and polycystic ovary syndrome (PCOS). However, the aetiological role of androgens in the pathogenesis of acne per se is far from being clear.Objective We aimed to evaluate adrenocortical function in women with post-adolescent severe acne in compa...

Background: There is evidence for differences between endocrinologists and other specialists in their approach to diagnosis and management of the polycystic ovary syndrome (PCOS). Objective: A mailed survey consisting of a simple questionnaire aiming to understand current practice for diagnosis and management of the PCOS by specialists across Eu...

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder of women of reproductive age and combined oral contraceptives (OCs) are often the first---line treatment of the syndrome by improving hyperandrogenism and regulating menstrual cycles. Oral contraceptives have some cardiovascular and metabolic effects that varies among different...