[Primary amenorrhea in adolescent girls. Incidence of isolated delayed menarche].

In its strict meaning, primary amenorrhea is defined as the absence of any menstruation in a young girl without genital malformations who has reached her complete morphological development. Twenty-four cases corresponding to this definition, with bone ages of at least 15 years, breasts for at least 2 years, and adult type pubic hair were examined. In only 10 could a cause be found: anorexia nervosa, slight hyperandrogenism, acquired intracranial lesion. The other 14 girls, mean age of 16.2 +/- 1.4 years, were considered as presenting with simple delayed menarche. They were not given treatment, although 4 of them had been given steroids in artificial cyclical form previously. The 8 who were followed finally spontaneously developed normal cycles at a mean age of 17.6 +/- 2.8 years, one not until 24 years. Such data should lead to avoiding unnecessary treatments.