Master the board step 3

Master the Boards: USMLE Step 3
Anovulation classically
presents with a history of
amenorrhea followed by
unpredictable bleeding
(prolonged unopposed
estrogen stimulates the
endometrium). Consider
the following diagnoses:
• Polycystic ovary
syndrome (PCOS)
• Hypothyroidism
• Pituitary adenoma
• Elevated prolactin
• Medications (e.g.,
antipsychotics,
antidepressants)
··
Anovulation → no corpus luteum production of progesterone → unopposed
estrogen → hyperplastic endometrium and irregular bleeding →
predisposition to endometrial cancer.
··
Increased testosterone: ↑LH levels → ↑theca cell production of androgens
→ hepatic production of SHBG is suppressed → ↑total testosterone and
↑free testosterone.
··
Ovarian enlargement: Ultrasound shows a necklacelike pattern of multiple
peripheral cysts (20–100 cystic follicles in each ovary). ↑androgens → multiple
follicles in various stages of development, stromal hyperplasia, and a
thickened ovarian capsule → bilaterally enlarged ovaries.
Diagnostic Testing
··
LH:FSH ratio = 3:1 (normal is 1.5:1).
··
Testosterone level is mildly elevated.
··
Pelvic ultrasound shows bilaterally enlarged ovaries with multiple subcapsular
small follicles and increased stromal echogenicity.
Treatment
··
Oral contraceptive pill treats irregular bleeding and hirsutism. The progestin
component prevents endometrial hyperplasia.
··
Spironolactone may also be used to suppress hair follicles.
··
Clomiphene citrate or human menopausal gonadotropin (HMG) is the
treatment of choice for infertility.
··
Metformin enhances ovulation and manages insulin resistance.
Adrenal or Ovarian Tumor
This is the diagnosis when the question describes rapid onset hirsutism and
virilization without a family history. DHEAS is markedly elevated in an adrenal
tumor; testosterone is markedly elevated in an ovarian tumor. The next
step is to order an ultrasound (adnexal mass) or CT (adrenal mass).
Management involves surgical removal of the tumor.
Congenital Adrenal Hyperplasia
(21-Hydroxyolase Deficiency)
This is the diagnosis when the question describes gradual-onset hirsutism
without virilization in the second or third decade that is associated with
menstrual irregularities and anovulation. Serum 17-hydroxyprogesterone
level is markedly elevated. Precocious puberty with short stature is common.
Family history may be positive.
Management involves corticosteroid replacement, which will arrest the signs
of androgenicity and restore ovulatory cycles.
478