why LH, FSH are high in PCOS?

[MudPhud20XX]

I am still having trouble understanding PCOS. I get that you have high estrogen due to fat cells making estrogen, then why would you still get high LH and FSH?

Also, why would using clomiphene work since it will still result in increased LH and FSH by blocking estrogen at hypothalamus.

Many thanks in advance.

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[solitarius]

Pretty sure FSH is low.

 

[MudPhud20XX]

Pretty sure FSH is low.

Check FA 14 page 581, they are all up.

 

[solitarius]

Yeah, well PCOS is a situation where the LH/FSH ratio is too high.

So either FSH is high but LH is higher or FSH is low but LH high. Anyway, Sattar says that estrone operates on the pituitary to suppress FSH. And Sattar is The Man.

 

[Macaroon_Berry]

Yeah, well PCOS is a situation where the LH/FSH ratio is too high.

So either FSH is high but LH is higher or FSH is low but LH high. Anyway, Sattar says that estrone operates on the pituitary to suppress FSH. And Sattar is The Man.

It can't be fsh is higher. To diagnose it you need LH:FSH >2 if I remember correctly

 

[solitarius]

It can't be fsh is higher. To diagnose it you need LH:FSH >2 if I remember correctly

My understanding of PCOS is that it's a high LH/FSH ratio that is exacerbated (i.e., somewhat positive reinforcement) over time with more LH and less FSH.

I didn't mean to imply that FSH is shut off completely.

 

[aspiringmd1015]

regardless, the ratio is elevated. sattar explains the mechanism well enough, and goljan says something similar.

 

[worldbeater]

LH and FSH are increased, due to lack of feedback inhibition of progesterone and estrogen.

Progesterone and estrogen are decreased, which causes the lack of feedback inhibition to their corresponding LH and FSH, cause those values to rise.

 

[Phloston]

I am still having trouble understanding PCOS. I get that you have high estrogen due to fat cells making estrogen, then why would you still get high LH and FSH?

Also, why would using clomiphene work since it will still result in increased LH and FSH by blocking estrogen at hypothalamus.

Many thanks in advance.

PCOS is due to GnRH dysregulation secondary to insulin resistance. That's why obesity is the biggest risk factor. When an obese woman with PCOS drops the weight, the problem often goes away.

Insulin resistance --> altered GnRH pulsation --> increased LH/FSH ratio --> LH spike occurs (high LH) before follicles are adequately matured (low FSH) --> anovulation + cysts

If you see this as an arrow-question on the USMLE, LH is up and FSH is down.

If you start getting into the specifics of how estrogen and testosterone feedback impact the LH/FSH you're overthinking it. The hormonal problem starts with GnRH dysregulation due to insulin resistance, so whilst estrogen + testosterone still exert negative feedback, the normal effect is disrupted.

From UpToDate:

"The serum concentration of follicle stimulating hormone (FSH) may be normal or low in PCOS, leading to an elevated LH/FSH ratio compared with normally cycling, early follicular phase young control women. However, neither an elevated serum LH concentration nor an increased LH/FSH ratio is part of the diagnostic criteria for PCOS. (See "Diagnosis of polycystic ovary syndrome in adults".)"