A 19-year-old collegiate gymnast comes to the clinic for evaluation of absent menstrual pe… — USMLE Step 2 CK

A 19-year-old collegiate gymnast comes to the clinic for evaluation of absent menstrual periods for the past 10 months. Menarche occurred at age 13, and her menses were previously regular, occurring every 28 to 30 days. She trains approximately 25 hours per week and follows a strict, calorie-restricted diet to maintain her competition weight. Four weeks ago, she sustained a tibial stress fracture. She does not use tobacco, alcohol, or illicit drugs. She is not sexually active. Vital signs show a blood pressure of 94/60 mm Hg and a heart rate of 52/min. Her BMI is $17.8 \text{ kg/m}^2$ . Physical examination is unremarkable except for fine, downy hair over her face and arms. Pelvic examination reveals normal female external genitalia and a normal appearing cervix.

Laboratory studies show:

Test	Result
$\beta$ -hCG, serum	Negative
Follicle-stimulating hormone	$2.1 \text{ mIU/mL}$
Luteinizing hormone	$0.8 \text{ mIU/mL}$
Prolactin	$8 \text{ ng/mL}$
Thyroid-stimulating hormone	$1.4 \text{ }\mu\text{U/mL}$
Estradiol	$15 \text{ pg/mL}$

A dual-energy x-ray absorptiometry (DEXA) scan reveals a Z-score of $-2.2$ at the lumbar spine. The patient is anxious about her bone health and requests a prescription to "fix her hormones." She states she must maintain her current training intensity for an upcoming championship. Which of the following is the most appropriate next step in the management of this patient?

Multidisciplinary intervention focusing on increased caloric intake and modified exerciseAnswer
B
Prescription of combined oral contraceptive pills
C
Initiation of transdermal estradiol and cyclic oral micronized progesterone
D
Administration of a bisphosphonate (e.g., alendronate)
E
Measurement of serum testosterone and dehydroepiandrosterone sulfate (DHEA-S)

Answer

The correct approach is a multidisciplinary intervention focusing on increased caloric intake and modified exercise.

This patient presents with classic signs of functional hypothalamic amenorrhea (FHA) due to relative energy deficiency in sport, part of the female athlete triad (low energy availability, menstrual dysfunction, and low bone mineral density). Her extreme exercise and caloric restriction suppress the hypothalamic-pituitary-ovarian axis, resulting in low GnRH pulsatility and subsequently low FSH, LH, and estradiol levels. The primary and most effective initial treatment for FHA is a multidisciplinary approach involving a physician, dietitian, and mental health professional to increase caloric intake and optimize energy availability. This restores normal hypothalamic function, leading to the resumption of spontaneous menses and improvement in bone mineral density.

Step-by-Step Solution

Interpret the clinical presentation and laboratory findings.

The patient has a low BMI, an intense exercise regimen, secondary amenorrhea, and low gonadotropins with low estradiol. This is classic for functional hypothalamic amenorrhea (FHA) secondary to relative energy deficiency in sport (the female athlete triad).

Establishing the etiology of the secondary amenorrhea is necessary to guide appropriate therapy.

Evaluate the patient's bone health status.

The DEXA scan shows a Z-score of -2.2, confirming low bone mineral density (osteopenia/osteoporosis) secondary to prolonged hypoestrogenism, complicated by a recent stress fracture.

Determining the severity of complications from FHA informs the urgency and modality of treatment.

Select the most appropriate initial management for FHA.

The primary, most effective treatment is reversing the energy deficit through multidisciplinary nutritional and psychological intervention.

Restoring energy availability naturally reactivates the hypothalamic-pituitary-ovarian axis, which is superior to pharmacologic therapy for restoring both menses and bone mineral density.

Key Concept

The initial management of functional hypothalamic amenorrhea (female athlete triad) is a multidisciplinary approach to increase energy availability. Combined oral contraceptives are contraindicated for bone protection because oral estrogen suppresses hepatic IGF-1, a critical hormone for bone formation.

Estimated Time:1m 30s

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