NBME 11: Drug to Suppress Precautious Puberty?

[MonsterHospital]

A 5 y.o girl developing breasts and scant pubic hair is given an IV bolus of Gn-RH that induces a marked serum increase in LH 1 hr later. What drug can be given to stop previous puberty?

a)leuprolide
b) tamoxifen
c)spironolactone
d) ketoconazole
e) testosterone
f) progesterone
g) ACTH
h) hydrocortisone

My guess is leuprolide given in a constant (non-pulsatile) fashion. Is this right? Also, could someone explain the significance of them giving her a bolus of GnRH and it spiking her LH? I didn't really use that bit of info to arrive at my answer, but I felt it was relevant.

---

Members don't see this ad.

 

[MrBeauregard]

I answered leuprolide on that one and I'm pretty sure it was correct, although I wouldn't mind some confirmation from someone else (I didn't buy expanded feedback on NBME 11). I also rationalized it similarly: non-pulsatile administration of leuprolide will eventually decrease LH/FSH secretion. As for the IV bolus of GnRH to look for a spike in serum LH: if I remember correctly from my endocrinology block, an IV bolus of GnRH can differentiate true precocious puberty (meaning a hypophyseal origin) from another cause precocious puberty. In order for the adenohypophysis to secrete LH/FSH, it must have been previously sensitized to the activity of GnRH from the hypothalamus. Administering an IV bolus and seeing a rise in serum LH confirms that the adenohypophysis has, in fact, been exposed to GnRH before and is thus able to secrete LH/FSH in response to GnRH. Had the test not elicited a rise in serum LH, it would mean that the precocious puberty was not "true", but was instead the result of some other non-pituitary pathology.

If anyone sees that I am completely incorrect, please correct the above explanation.

 

[Valadi]

Leuprolide is all I've seen peds or peds/endo guys use for true precoc puberty. MBs explanation for the GnRH test is what I remember as well.