Prevalence of polycystic ovary syndrome under NIH criteria among the tenth-grade Chinese schoolgirls in Guangzhou area: a cross-sectional epidemiological survey.

BACKGROUND: Polycystic ovary syndrome (PCOS) is currently considered to have a peri-adolescence onset and continuously influence the reproductive and metabolic health of the patients, while the diagnostic criteria among adolescent population haven't been universally unified till now. This survey seeks to preliminarily evaluate the prevalence of PCOS in the tenth grade schoolgirls in Guangzhou area under NIH criteria and analyze the clinical features of adolescents with PCOS. METHODS: The cross-sectional epidemiological survey was carried out among the tenth grade schoolgirls in Guangzhou area by the method of cluster sampling. The contents of this survey included the questionnaire, physical exams and serum measurements. Until now, totally 1294 girls underwent this survey and 1095 serum samples were restored. 235 non-hirsute (mFG < 6), postmenarcheally 2-year girls were randomly selected as the control group, among which the cut-off value of biochemical hyperandrogenemia was set accordingly. The prevalence of PCOS among this population was preliminarily evaluated according to the NIH criteria. RESULTS: Along with the increase of gynecological age, the menstruations of girls was becoming more regular and the incidence of oligomenorrhea or amenorrhea was declining. Even among those who were less than 2 years after menarche, those whose menstrual cycle were longer than 90 days accounted for lower than 5%. The 95th percentile of mFG score was 6 among the girls who were < 2 years after menarche, and 5 among the girls who were > 2 years after menarche. Among the 235 healthy girls, the 95th percentile values of Testosterone (T), Free androgen index (FAI) and Androstenedione (A2) were 2.28 nmol/mL, 4.37, and 5.20 nmol/mL respectively. Based on the NIH criteria, the prevalence of PCOS in this survey was 3.86%. The prevalence of adolescent PCOS tend to slightly increase with age and gynecological age, but the difference was not statistically significant. The prevalence of PCOS among obese girls was markedly higher than that in lean girls. CONCLUSION: Based on the NIH criteria, the prevalence of PCOS among the tenth grade schoolgirls in Guangzhou area was 3.86%. The diagnosis of hyperandrogenism among adolescents should also be based on both clinical and biochemical parameters.