A 14-year-old girl is brought to the office by her mother because she has not started menstruating. She is otherwise healthy and has no chronic medical conditions. The patient takes no daily medications and does not use tobacco, alcohol, or illicit drugs. She is not sexually active. Her mother and older sister underwent menarche at age 13. Height is at the 15th percentile and weight is at the 20th percentile for age. Vital signs are normal. Physical examination shows normal heart sounds without murmur. There is no breast development or axillary hair. The abdomen is soft, nontender, and nondistended. Pelvic examination reveals normal external female genitalia and no pubic hair. Ultrasound confirms the presence of a uterus. Which of the following is the best next step in management of this patient?

Question

A 14-year-old girl is brought to the office by her mother because she has not started menstruating.  She is otherwise healthy and has no chronic medical conditions.  The patient takes no daily medications and does not use tobacco, alcohol, or illicit drugs.  She is not sexually active.  Her mother and older sister underwent menarche at age 13.  Height is at the 15th percentile and weight is at the 20th percentile for age.  Vital signs are normal.  Physical examination shows normal heart sounds without murmur.  There is no breast development or axillary hair.  The abdomen is soft, nontender, and nondistended.  Pelvic examination reveals normal external female genitalia and no pubic hair.  Ultrasound confirms the presence of a uterus.  Which of the following is the best next step in management of this patient?

Quizplus · Accepted Answer

Explanation: 11ec25c8_d669_883c_bc81_f7fd8f01dacf_MD0003_00 This patient has primary amenorrhea, the absence of menarche in girls age ≥13 with no secondary sexual characteristics (or girls age ≥15 with secondary sexual characteristics [eg, axillary/pubic hair]). Initial evaluation is with a pelvic ultrasound to determine the presence or absence of a uterus. In those with a uterus (such as this patient), the best next step is an FSH level, which helps distinguish between central and peripheral causes of amenorrhea in the hypothalamic-pituitary-ovarian (HPO) axis. Central causes of amenorrhea (ie, hypothalamic, pituitary) have a low to normal FSH level due to either decreased GnRH (hypothalamic) or decreased FSH production/secretion (anterior pituitary). Peripheral causes of amenorrhea (ie, ovarian) have a high FSH level. High FSH levels occur due to a lack of ovarian estrogen and inhibin production; a lack of feedback inhibition to the hypothalamus and pituitary results in constant FSH production. Anatomic defects (eg, imperforate hymen) are also a peripheral cause of amenorrhea but do not affect the HPO axis and, therefore, are associated with normal FSH levels. Based on the FSH level, additional testing for specific etiologies is performed (eg, karyotype analysis, MRI of pituitary). (Choice A) Absent breast development indicates a lack of estrogen; an estrogen level provides no additional information. (Choice C) A GnRH stimulation test is not performed in evaluation of primary amenorrhea because it cannot distinguish between hypothalamic and pituitary etiologies and provides no additional information. (Choice D) In contrast to this patient, those without a uterus undergo karyotype analysis to evaluate for male (eg, androgen insensitivity [46,XY]) and female anatomic (eg, müllerian agenesis [46,XX]) causes of amenorrhea. Karyotype analysis is also performed in patients with a uterus and high FSH level to evaluate for Turner syndrome (45,XO). (Choice E) MRI of the pituitary is performed in patients with a uterus and low/normal FSH levels to evaluate for pathologic causes (eg, pituitary mass). In contrast, those with a high FSH level do not require an MRI of the pituitary. (Choice F) This patient could have reassurance and observation if she had primary amenorrhea with secondary sexual characteristics, as this is normal until age 15. Educational objective: Primary amenorrhea is the absence of menarche in girls age ≥13 with no secondary sexual characteristics. In patients with a uterus, the best next step is an FSH level test, which distinguishes between central (low/normal FSH) and peripheral (high FSH) causes of amenorrhea. References: Evaluation and management of adolescent amenorrhea. (http://www.ncbi.nlm.nih.gov/pubmed/20840249)

A 14-Year-Old Girl Is Brought to the Office by Her