2 OB/GYN NBME Form 1 Questions..

[ilovemed1]

Could anyone please explain the following 2 questions? I am having trouble figuring them out/understanding them.. thank you!

1) "A 20-year-old woman comes to the physician because of a 3-year history of mild-to-moderate hair growth over her face, breasts, and lower abdomen that has become slightly worse during the past 2 years. She has no history of serious illness and takes no medications. Menses occur at regular 28-day intervals. Examination shows excessive hair growth over the upper lip, chin, lower abdomen, and pubic area. Three days after the onset of her menstrual period, serum studies show"

Follicle-stimulating hormone 10 mIU/mL
Luteinizing hormone 12 mIU/mL
Dehydroepiandrosterone sulfate 1.5 μg/mL (N=0.5–5.4)
17α-Hydroxyprogesterone 25 ng/dL (N=20–300)
Testosterone 2.8 nmol/L (N<3.5)

a) decrease aromatase
b) inc testosterone (wrong)
c) dec progest
d) inc estrogen
e) inc 5a reductase activity

from what i have read, i think E is the correct answer but im not sure why..

2) "A 27-year-old primigravid woman at 34 weeks' gestation comes to the physician because of a 1-day history of severe anxiety, sweating, and a rapid heartbeat. She is oriented to person and time but not to place. Her temperature is 37.8°C (100°F), pulse is 130/min, respirations are 27/min, and blood pressure is 160/100 mm Hg. The thyroid gland is nontender and diffusely enlarged on palpation. Deep tendon reflexes are 4+; there is4+ clonus at the ankles."

Laboratory studies show:
Hemoglobin 13 g/dL
Hematocrit 39%
Leukocyte count 12,000/mm3
Platelet count 250,000/mm3

In addition to β-adrenergic blocking agent therapy, which of the following is the most appropriate next step in management?

a) cephalosporin
b) levothyroxine (I read on a different site that this may be the answer....i dont get why though)
c) potassium iodide
d) ptu
e) irradiation of the thyroid

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[justin1390]

I'll tackle the first one a bit. I am confused in general as to the diagnosis. They are obviously pointing toward a picture of virilization. The problem is that this isn't a prototypical LH/FSH of 3:1 for a PCOS picture. Perhaps it's because she is having a period? But that in itself is confusing because these women will often have irregular periods. She is regular. What you can expect is an elevated total and free testosterone level in a PCOS picture. Since her level is normal, we can say this doesn't fit PCOS very well. Estrogen may be normal or slightly decreased in PCOS. And so we have to turn to other options.

Other DDx in this question could be hyperthecosis (lots of virilization with marked increase in androgens) or an androgen producing tumor (would also have lots of androgens, likely irregular periods). So that leads us to what I think the dx is, which is increase alpha-5-reductaste activity. This is actually a naturally occurring phenomena in some women which leads to disturbing (to them) virilization. However, there are no hormonal abnormalities. If you remember, alpha-5-reductase converts testosterone into dihydrotestosterone, which is 3 times more potent in hair follicles than testosterone. So I agree with you, I think this woman has a benign increase in peripheral A-5-R activity.

 

[J ROD]

Second one sounds like thyroid storm. Since levothyroxine threats hypo and not hyper thyroid. I am not going to say that one. I would go either PTU or Potassium Iodide. From what I have read, PTU is not generally used in 2nd and 3rd trimester. But would probably be a better choice than the iodine in pregnancy.

So, I believe Methimazole is favored over PTU at this stage of the game in her pregnancy, but I think it would still be appropriate to use in the case of "the storm".

 

[ilovemed1]

Thank you that was a great explanation! I really appreciate it. @J DUB so I had put potassium iodide and got it wrong..when i read someone had put levo i was like...no that definitely cant be right..i couldnt justify using it (unless its some negative feedback sort of thing??) or PTU (as its unfavorable like you said). I'll go with PTU.