Master the board step 3

Master the Boards: USMLE Step 3
Hypothalamic-Pituitary Failure
This is the diagnosis when there are no sexual characteristics but the uterus is
normal on ultrasound and FSH levels are low. It may be due to stress, excessive
exercise, or anorexia nervosa. Kallmann syndrome is the likely diagnosis
when the case also describes anosmia (hypothalamus doesn’t produce GnRH).
CNS imaging (CT head) will rule out a brain tumor.
Management involves estrogen and progesterone replacement for development
of secondary sexual characteristics.
Secondary Amenorrhea
This is diagnosed when one of the following conditions presents:
··
Regular menses are replaced by an absence of menses for 3 months.
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Irregular menses are replaced by an absence of menses for 6 months.
Steps in the Workup of Secondary Amenorrheap
Steps in the Workup
1. Pregnancy Test
(ß-hCG)
2. Thyrotropin (TSH) (rule
out hypothyroidism)
3. Prolactin (rule out
elevation)
4. Progesterone
Challenge Test (PCT)
5. Estrogen–Progesterone
Challenge Test (EPCT)
Next Step in Management
An elevated TRH in primary hypothyroidism → ↑ prolactin.
Treat hypothyroidism with thyroid replacement for rapid restoration of menstruation
If elevated:
1) Review medications: Antipsychotics and antidepressants have antidopamine side effect
→ ↑ prolactin
2) CT or MRI of head to rule out pituitary tumor
– Tumor < 1 cm: give bromocriptine (dopamine agonist)
– Tumor > 1 cm: treat surgically
3) If the cause of elevated prolactin is idiopathic, treat with bromocriptine.
• Positive PCT: Any withdrawal bleeding is diagnostic of anovulation.
– Treatment: Cyclic progesterone to prevent endometrial hyperplasia. Clomiphene
ovulation induction is done if pregnancy is desired.
• Negative PCT: Inadequate estrogen or outflow tract obstruction
• 3 weeks of oral estrogen followed by 1 week of progesterone
• Positive EPCT: Any withdrawal bleeding is diagnostic of inadequate estrogen. Next step is
to get an FSH level.
– ↑ FSH is ovarian failure. Y chromosome mosaicism may be the cause if patient is < 25
years. Order a karyotype for confirmation.
– ↓ FSH is hypothalamic–pituitary insufficiency. Order a brain CT/MRI to rule out
a tumor. Give estrogen-replacement therapy to prevent osteoporosis and cyclic
progestins to prevent endometrial hyperplasia.
• Negative EPCT: Diagnostic of an outflow tract obstruction or endometrial scarring
(e.g., Asherman syndrome). Order a hysterosalpingogram to identify the lesion.
Management: Adhesion lysis followed by estrogen stimulation of the endometrium. An
inflatable stent prevents re-adhesion of the uterine walls.
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