amenorrhea primary amenorrhea http://id.loc.gov/authorities/subjects/sh85004216 http://purl.obolibrary.org/obo/HP_0000786 RJ478.5.A43 Primary amenorrhea can be diagnosed in children by age 14 if no secondary sex characteristics, such as enlarged breasts and body hair, are present. In the absence of secondary sex characteristics, the most common cause of amenorrhea is low levels of FSH and LH caused by a delay in puberty. Gonadal dysgenesis, often associated with Turner's Syndrome, or premature ovarian failure may also be the cause. If secondary sex characteristics are present, but menstruation is not, primary amenorrhea can be diagnosed by age 16. A reason for this occurrence may be that a person phenotypically female but has a Y chromosome, a situation known as androgen insensitivity syndrome. If undescended testes are present, they are often removed after puberty (~21 years of age) due to the increased risk of testicular cancer. In the absence of undescended testes, an MRI can be used to determine whether or not a uterus is present. Müllerian agenesis causes around 15% of primary amenorrhea cases. If a uterus is present, outflow track obstruction may be the cause of primary amenorrhea. primary amenorrhoea