Preface

Polycystic ovary syndrome (PCOS) is a major health problem. It is a heterogeneous hormone-imbalance disorder that occurs in reproductive-aged women worldwide and is characterized by hyperandrogenism, ovulatory process dysfunction and polycystic ovaries.

PCOS is affected by various factors and there are no unique diagnostic criteria in different regions due to the heterogeneity of its clinical manifestations and endocrine system changes. Therefore, it is often difficult to accurately diagnose women with PCOS, as the signs and symptoms of PCOS can vary among individuals. Although PCOS is usually diagnosed during the early reproductive years, its precise pathogenesis remains unclear. An increasing number of studies have demonstrated that the insulin signaling pathway has an important role in the pathophysiology of PCOS, including phosphatidylinositol 3-kinase and protein kinase B signaling, which is critically implicated in insulin resistance, androgen secretion, obesity and follicular development. PCOS manifests as defective ovarian steroid biosynthesis and hyperandrogenemia, and 50%–70% of women with PCOS exhibit insulin resistance and are hyperinsulinemic, indicating that insulin resistance and hyperinsulinism may have an important role in the pathophysiology of PCOS.

This book provides a comprehensive overview of the current state of the art in PCOS research to benefit the population of women with PCOS. It is my hope that this book is meaningful to the clinicians who care for women with PCOS and to the researchers who investigate the complexities of this disease. We sincerely thank all the authors for their contributions to our book. At last, we hope that this book is meaningful to the clinicians who care for women with PCOS and to the researchers who investigate the complexities of this disorder.

> **Dr. Zhengchao Wang** Provincial Key Laboratory for Developmental Biology and Neurosciences, College of Life Sciences, Fujian Normal University, Fuzhou, China

Section 1
