Review Question - QID 108597

This patient is an athlete who presents with primary amenorrhea, fatigue, feeling cold, and low body mass, which together suggest functional hypothalamic amenorrhea (HA). FSH and estrogen levels are the next best tests and would be low due to increased corticotropin releasing hormone and subsequently decreased pulsatile GnRH.

HA can cause both primary and secondary amenorrhea. In this patient with thelarche, adrenarche, and a growth spurt but no menarche, it is likely that her hypothalamic function was disrupted after puberty began. She is at risk for the “female athlete triad”:

1. Hypothalamic amenorrhea
2. Eating disorder
3. Osteoporosis due to the loss of estrogenic bone protection

In this patient, there is also some suggestion of an eating disorder, as constipation, fatigue, thinning hair, and borderline tachycardia may be due to inadequate food/fluid intake and nutritional deficiency. HA is also associated with severe stress and chronic illness. HA is ultimately a diagnosis of exclusion, so this patient’s diagnostic workup should ultimately include all of the listed answer choices to rule out other common causes of amenorrhea. However, a low FSH with low estrogen would be most useful. A progesterone challenge test is a more indirect way to yield the same conclusion. In a woman with a functioning hypothalamic system and a patent outflow tract, progesterone will stimulate shedding of the endometrium. If no withdrawal bleed occurs, a progesterone + estrogen challenge test can be performed. A resulting withdrawal bleed would indicate a problem with the hypothalamic system, as in HA. Of note, an elevated FSH with a low estrogen would suggest a diagnosis of premature ovarian insufficiency or menopause, as these conditions would be due to decreased ovarian production of estrogen with resulting lack on inhibition on pituitary secretion of FSH.

Incorrect Answers:
Answer 1: A pelvic exam may be performed to look for an imperforate hymen or transverse vaginal septum, which often presents with hematocolpos or cryptomenorrhea, respectively, and cyclic abdominal pain. They are relatively common causes of primary amenorrhea and would not affect other pubertal development such as thelarche or adrenarche. Though it is possible for this patient to have either anomaly, her risk factors and physical exam suggest HA instead.

Answer 2: Prolactin level is useful for diagnosing a hyperprolactinemia as the cause of primary amenorrhea. It is most commonly due to a functioning pituitary adenoma, which may cause symptoms such as galactorrhea, headache, and bitemporal vision loss from compression of the optic chiasm (late stage presentation). Evaluation includes brain MRI, and surgical resection may be required. Though this patient has migraines, they seem to be longstanding. Furthermore, headaches from a pituitary adenoma should not cause aura.

Answer 3: TSH levels would be high in hypothyroidism, which could present with some of this patient’s symptoms: cold intolerance, constipation, fatigue, and hair thinning. It could also lead to primary amenorrhea. However, it generally causes weight gain rather than weight loss, and the patient’s other symptoms and age make HA more likely.

Answer 4: Decreased GnRH pulsatility is the underlying cause of this patient’s amenorrhea, but because GnRH is scarce in the peripheral circulation, has a short half-life, and fluctuates widely, it is not routinely tested. Treatment with pulsatile GnRH infusions is one option for patients with HA and infertility.

Bullet Summary:
Functional hypothalamic amenorrhea is associated with low body weight and excessive exercise. It results from elevated CRH, which causes decreased GnRH pulsations and subsequently low FSH, LH, and estrogen.