Pituitary tumor question

[Phloston]

Uworld has in one of its explanations that an LH/FSH-secreting tumor results in hypogonadism.

I'm a bit confused by this. Could someone please explain.

If the tumor were instead GnRH-secreting, then I could understand that continual secretion would ultimately decrease gonadotroph secretion (similar to leuprolide / goserelin), but we're talking LH or FSH.

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[islandCrazy]

Does this question speak about down-regulation or desensitization of the FSH and LH receptors?

 

[Phloston]

Does this question speak about down-regulation or desensitization of the FSH and LH receptors?

The question didn't have anything to do with LH/FSH, but one of the incorrect answers (with subsequent explanation) discussed that a gonadotrophic tumor of the pituitary, although rare, results in "hypogonadism and mass effect."

I can understand a mass effect of a prolactinoma, for instance, causing secondary hypogonadism, but we're talking an LH-/FSH-secreting tumor itself.

 

[Charles_Carmichael]

The question didn't have anything to do with LH/FSH, but one of the incorrect answers (with subsequent explanation) discussed that a gonadotrophic tumor of the pituitary, although rare, results in "hypogonadism and mass effect."

I can understand a mass effect of a prolactinoma, for instance, causing secondary hypogonadism, but we're talking an LH-/FSH-secreting tumor itself.

Could they have meant hypogonadism due to mass effect, as in compression and destruction of LH/FSH-secreting cells (by the tumor) leads to hypogonadism?

Btw, I don't think that the mass effect of a prolactinoma is the main cause for secondary hypogonadism. The high levels of prolactin produced by the tumor will cause hypogonadism (by suppressing release of GnRH). Symptoms due to the mass effect caused by a pituitary tumor would include things like bitemoral hemianopia from compressing the optic chiasm, etc.

 

[Phloston]

Could they have meant hypogonadism due to mass effect, as in compression and destruction of LH/FSH-secreting cells (by the tumor) leads to hypogonadism?

Btw, I don't think that the mass effect of a prolactinoma is the main cause for secondary hypogonadism. The high levels of prolactin produced by the tumor will cause hypogonadism (by suppressing release of GnRH). Symptoms due to the mass effect caused by a pituitary tumor would include things like bitemoral hemianopia from compressing the optic chiasm, etc.

I agree with the latter, but the mass effect normally affects gonadotrophs first regardless.

UWorld also has it where you can't C+P or PrntScr, but it basically just showed a table with the various pituitary tumors, their relative % occurrences and then their symptoms, and "hypogonadism, mass effect" was in the Sx cell for pituitary gonadotroph tumors.

It's probably not worth it to over-think it anyway.

 

[gravitywave]

the hypogonadism is due to mass effect in gonadotrophic tumors, since most dont make functional hormones anyway - recall that LH and FSH have subunits and that it's much more frequent to see these messed up cells making subunits alone as opposed to fully formed hormones. you can see hypergonadism from FSH secreting tumors but it's quite rare. most commonly, there are no hormonal effects at all unless the tumor is large enough to start compressing the pituitary stalk.

prolactinomas are known for hypogonadism (among other things) because it's much more common for them to produce PRL in an unregulated fashion, even when microadenomas. they can of course cause pituitary disfunction via mass effect as well.