Causes of primary amenorrhea: a report of 295 cases in Thailand.

AIMS: The aim of this study was to determine the prevalence of etiologic causes of primary amenorrhea in Thailand. METHODS: A retrospective study was performed using 295 complete medical records of women with primary amenorrhea who attended the Gynecologic Endocrinology Clinic, Department of Obstetrics and Gynecology, Faculty of Medicine Siriraj Hospital, Mahidol University, Thailand from September 1992 to February 2009. RESULTS: The three most common causes of primary amenorrhea were Müllerian agenesis (39.7%), gonadal dysgenesis (35.3%), and hypogonadotropic hypogonadism (9.2%). Amongst 88 cases of gonadal dysgenesis, 59 cases (67.0%) incurred abnormal karyotype including 45X (n=21), mosaic (n=31), and others (n=7). CONCLUSIONS: The present study has currently been the largest case series of primary amenorrhea. Müllerian agenesis is the most prevalent cause in our study, while gonadal dysgenesis is the most common cause in the largest-scale study in the USA. Hence, racial, genetic and environmental factors could play roles in the cause of primary amenorrhea.