PCOS Phenotypes and Classification: Characteristics of PCOS in China
A Science-Backed Analysis of PCOS Subtypes, Chinese Epidemiological Features, and the Clinical Significance of PCOS Phenotyping
In our previous article, we introduced what PCOS is, its causes, and its health impacts. This article provides a deeper analysis of the characteristics of PCOS in China, PCOS phenotyping, and the clinical significance of subtype classification.
1. Characteristics of PCOS in China
The epidemiological features of PCOS in China can be summarized as "three highs and one low" — high prevalence, high proportion of hyperandrogenemia, high rate of secondary metabolic syndrome, and low clinical awareness.
High Prevalence: The prevalence of PCOS among women of reproductive age is 5%–10%, meaning that 1–2 out of every 10 women of childbearing age are PCOS patients. This incidence rate far exceeds the combined incidence of all malignancies (400–500 per 100,000, or 0.4%–0.5%).
High Proportion of Hyperandrogenemia: The prevalence of hyperandrogenemia among Chinese PCOS patients is approximately 85%. Under the influence of excess androgens — particularly testosterone — the ovaries of PCOS patients exhibit reduced or absent ovulation. Obesity, especially abdominal obesity, is closely associated with hyperandrogenemia.
High Rate of Secondary Metabolic Syndrome: PCOS patients are a high-risk population for impaired glucose tolerance (IGT) and type 2 diabetes. Research indicates that the underlying cause of insulin resistance in PCOS patients is a reduction in insulin-dependent receptor tyrosine phosphorylation levels.
Low Clinical Awareness: Weight management in PCOS patients is challenging, endocrine therapy outcomes are often suboptimal, and the medical community generally considers PCOS a benign but incurable condition. These factors contribute to patients either losing confidence in treatment or not taking the condition seriously.
2. PCOS Phenotyping and Classification
PCOS phenotyping is based on the following clinical features:
- Oligoovulation or anovulation (OA)
- Clinical or biochemical evidence of hyperandrogenism (HA)
- Polycystic ovarian morphology (PCO) on ultrasound
- Exclusion of other known causes of androgen excess
By combining the first three clinical features, the 2011 Chinese PCOS diagnostic standard — tailored to the metabolic characteristics of Asian populations — designates menstrual irregularity as a mandatory condition, using OA as a diagnostic prerequisite. This classification system includes phenotypes A, B, and D.
Research shows that the prevalence of PCOS phenotypes A, B, C, and D in the Chinese population is 29%, 19%, 37%, and 15%, respectively [3].
Considering patient prognosis and long-term management, the Chinese PCOS standard places greater emphasis on metabolic status. In addition to diagnostic criteria, it proposes a clinical subtyping system based on:
- Presence or absence of obesity and central obesity.
- Presence or absence of impaired glucose tolerance, diabetes, or metabolic syndrome (MS).
- Presence or absence of hyperandrogenism — distinguishing classic PCOS (menstrual irregularity with hyperandrogenism, with or without PCO) from non-hyperandrogenic PCOS (menstrual irregularity with PCO only). Classic PCOS patients exhibit more severe metabolic disturbances, while non-hyperandrogenic PCOS is comparatively milder [4].
3. Clinical Significance of PCOS Phenotyping
01. Guiding Lifestyle Modification
As classic PCOS phenotypes, types A and B carry increased risks of obesity, insulin resistance, and metabolic syndrome compared to type D and the general population. However, lifestyle intervention remains the foundational treatment for all PCOS patients — whether obese or non-obese — including dietary modification, exercise, and behavioral therapy. Weight control through lifestyle adjustment in PCOS patients helps improve outcomes in assisted reproductive technology (ART) treatments.
02. Predicting Ovarian Response and ART Outcomes
Different PCOS phenotypes exhibit varying ovarian responses and risks of ovarian hyperstimulation syndrome (OHSS) during controlled ovarian hyperstimulation (COH). In in vitro fertilization (IVF) treatment, it is essential to identify different PCOS subtypes, perform pretreatment before assisted reproduction, and adjust medication protocols appropriately to individualize ovulation induction strategies.
03. Strengthening Pregnancy Monitoring
Women with PCOS face increased risks of gestational diabetes mellitus, hypertensive disorders of pregnancy, and associated maternal complications during pregnancy, as well as elevated risks of preterm delivery and small-for-gestational-age (SGA) infants. These pregnancy-related risks are particularly pronounced in hyperandrogenic PCOS phenotypes. Therefore, during follow-up of pregnant PCOS patients, clinicians should pay closer attention to pregnancy complications in classic PCOS phenotypes.
04. Emphasizing Long-Term Management
A 10-year follow-up of different PCOS phenotypes revealed a significant reduction in androgen levels. After 15 years of follow-up, waist circumference increased markedly. After 20 years, ovarian volume decreased in phenotypes A, C, and D. Over the 20-year follow-up period, PCOS women showed decreased androgen levels and ovarian volume, increased ovulatory cycles, and milder symptoms. The proportion of classic PCOS (especially type A) declined, and some patients no longer met PCOS diagnostic criteria. However, as a lifelong chronic condition, metabolic diseases in PCOS increase with age. Therefore, the focus of long-term management should be on the prevention and control of metabolic complications.
Accurately identifying whether a PCOS patient has the hyperandrogenemic phenotype has significant implications for subsequent diagnosis and treatment. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) for measuring hormone levels in PCOS patients is increasingly recommended by the industry as the preferred method for precise hormone profiling.
References
[1] Chinese Expert Consensus on Ketogenic Diet Intervention for Polycystic Ovary Syndrome (2018 Edition). Journal of Clinical Medicine in Practice, 2018, 23(1): 1–4.
[2] Lin J, et al. Diagnosis, Phenotyping, and Clinical Significance of Polycystic Ovary Syndrome. Chinese Journal of Practical Gynecology and Obstetrics, 2019, 35(3): 267–271.
[3] Xue S, Yang G. Advances in Diagnosis and Treatment of Polycystic Ovary Syndrome. Chinese Journal of Endocrinology and Metabolism, 2020, 36(1): 88–92.
[4] Diagnostic Criteria for Polycystic Ovary Syndrome. National Health Industry Standard of the People's Republic of China, WS 330-2011.
PCOS Phenotypes · PCOS Classification · PCOS Subtypes · PCOS in China · Hyperandrogenism PCOS · PCOS Metabolic Syndrome · PCOS Diagnosis · Classic PCOS · Non-Hyperandrogenic PCOS · PCOS Long-Term Management · LC-MS/MS Hormone Testing · Ovarian Hyperstimulation Syndrome · Assisted Reproductive Technology · Women's Health · In Vitro Diagnostics · VirtueDx
