a prospective study of etiology of primary amenorrhea with especial evaluation for non classic congenital adrenal hyperplasia due to 21 hydroxylase deficiency

amenorrhea, an absence of menses is a symptom that generally brings teenagers for evaluation. this study was undertaken to determine the etiology of primary amenorrhea with especial concern to non classic congential adrenal hyperplasia (nc-cah)-due 21 hydroxylase deficiency among female adolescents refered to clinics of pediatric endocrinology of tehran and iran university of medical sciences and private office. one hundred and five female adolescents were studied. all patients were examined by pediatric endocrinologist.routine lab tests, fsh, lh, prolactin, t4, tsh, 17-hydroxyprogesterone and in some cases acth stimulation test for screening of nc-cah due to 21 oh deficiency were performed. chromosmal analysis, sonography of the ovaries and ct scan or mri of the brain was performed in some of them. forty-three patients (41%) had ypergonaldotropic hypogonadism and sixty two patiens (59%) ahd hypogonadotropic hypogonadism. turner’s syndrome and constitutional delay of puberty were the most common causes of primary amenorrhea in our study. the frequency of primary amenorrhea in our study. the frequency of primary amenorrhea due to 21-oh deficient nc-cah was 6.6% in overall (105 cases). this study shows that in a population with high incidence of consanguineous marriages, some rare genetic disorders such as 21 oh deficient nc-cah are relatively common