Chapter 4 AMENORRHEA: PRIMARY

Primary amenorrhea is defined as the absence of menses by 16 years of age in the presence of normal growth and secondary sexual characteristics or lack of menses by 14 years of age in the absence of secondary sexual characteristics. In the classification of primary amenorrhea, hypogonadism refers to gonads that are not functioning, and this condition is associated with a hypoestrogenic state; eugonadism refers to gonads that maintain normal steroidogenesis, and this condition is associated with a well-estrogenized state. An evaluation of breast development can be used to determine a patient’s estrogen status. The pelvic examination then further narrows the potential causes by determining the presence or absence of a normal mullerian system.

The most common cause of primary amenorrhea is primary ovarian failure resulting from gonadal dysgenesis, most commonly as a result of Turner syndrome. The second most common cause of primary amenorrhea is congenital absence of the uterus and vagina, followed by idiopathic hypogonadotropic hypogonadism. Another cause of secondary amenorrhea involves eating disorder. The incidences of eating disorders such as anorexia and bulimia are highest during the adolescent years. Anorexia nervosa has a prevalence of 1% in the United States. The so-called female athlete triad—characterized by disordered eating, osteoporosis or osteopenia, and amenorrhea in the setting of excessive exercise—overlaps with eating disorders.

The first step in the evaluation of primary amenorrhea (Fig. 4-1) is documentation of the history and a physical examination. If secondary sexual characteristics are not present, follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels should be measured. FSH and LH levels lower than 5 IU/L indicate hypogonadotropic hypogonadism. If the FSH level exceeds 20 IU/L and the LH level exceeds 40 IU/L, hypergonadotropic hypogonadism is present; in that case, karyotype analysis is indicated.