Mehl. PCOS + progesterone test 03-24 (1)

Question 1

M. High BMI female ->?

Answer 1

insulin resistance.

Question 2

M. Insulin resistance causes what GnRH changes? LH, FSH?

Answer 2

abnormal GnRH pulsation -> leads to incr. LH and decr. FSH.

This is often truncated as just saying there’s an incr. LH/FSH ratio. Some students think FSH is also ­incr. but it’s just the ratio that is increased­. That’s wrong. FSH is low.

Question 3

M. LH normally acts on ….? what effect normal?

Answer 3

LH normally acts on the theca lutein cells of the ovaries to make androgens. Since LH is ­high, we get hirsutism.

Question 4

M. FSH normally does what? what we have?

Answer 4

FSH normally stimulates follicular development. Since FSH is decr., we have poor follicular development, leading to failure of a Graafian follicle to rupture during ovulation. The unruptured follicle is retained as a follicular cyst.

Question 5

M. Failure of ovulation is called anovulation. This term is exceedingly HY on USMLE. It presents as a female with irregular periods.

Answer 5

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Question 6

M. Anovulation is a broader term than PCOS, as it can be due to other conditions as well, such as? 2

Answer 6

hypothyroidism and Cushing syndrome.

Question 7

M. But when you hear the word “anovulation” alone, it is usually used as synonymous for the same mechanism as PCOS – i.e., high-BMI female who has irregular periods due to abnormal GnRH pulsation causing an incr.­ LH/FSH ratio, with the decr. FSH causing failure of follicular rupture.

Answer 7

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Question 8

M. So high-BMI female + irregular periods = ?

Answer 8

anovulation till proven otherwise.

Question 9

M. Anovulation (high BMI + irregular periods) + hirsutism =?

Answer 9

PCOS.

Question 10

M. In clinical practice, part of the PCOS diagnosis requires ????

Answer 10

requires ultrasounds showing 11+ cysts bilaterally (Amsterdam criteria). But USMLE doesn’t assess this. You just need to know anovulation + hirsutism = PCOS

Question 11

M. Normally when a follicle ruptures, the remnant is called the corpus luteum, which secretes progesterone.

Answer 11

Progesterone inhibits growth of endometrium; estrogen stimulates growth of endometrium.

Question 12

!!!M. Women who have anovulation have what levels of progesterone?

Answer 12

decr. progesterone production because they don’t form a corpus luteum.

This means they have INCREASED­ estrogen in comparison to progesterone. We call this unopposed estrogen. This is one of the highest yield phrases for USMLE.

Question 13

M. Unopposed estrogen means incr­ risk of ???

Answer 13

Unopposed estrogen means incr.­ risk of endometrial hyperplasia and, in turn, ­incr. risk of endometrial carcinoma.

Question 14

M. The Q can give you a high-BMI female who’s post-menopausal + has vaginal bleeding. Answer is just straight-up endometrial biopsy. Student asks how we know it’s endometrial cancer. My response is, if she’s overweight, this implies she was probably overweight in the past, which implies she’s had history of anovulatory cycles and endometrial hyperplasia, leading to ­ endometrial cancer risk.

Answer 14

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Question 15

M. All patients have risk for what?

Answer 15

Because insulin resistance is the basis for PCOS, patients are at ­incr. risk of developing type II diabetes.

Question 16

M. As mentioned above, hypothyroidism and Cushing syndrome are also HY causes of anovulation on USMLE.

Answer 16

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Question 17

M. ­ Incr. Glucocorticoids in Cushing syndrome can cause insulin resistance and anovulation, where the diagnosis can appear like PCOS.

The difference is PCOS is idiopathic in response to high BMI – i.e., it is not caused by a known secondary etiology like Cushing syndrome, even though the presentations can be similar.

Answer 17

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Question 18

M. Hypothyroidism leads to ­incr. thyroid-releasing hormone (TRH), which stimulates prolactin, which causes abnormal GnRH pulsation. Even though this is the mechanism, the caveat I issue is that USMLE does not directly assess this, and it is infinitely more important you know that the mechanism for prolactin secretion is decr. dopamine, or overt dopamine-2 receptor antagonism (i.e., for severance of pituitary stalk Qs)

Answer 18

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Question 19

M. test.
Progesterone withdrawal test is the process of giving progesterone followed by seeing if bleeding occurs following its withdrawal. It can be used to help diagnose the cause of oligo- or amenorrhea.

Answer 19

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Question 20

M. test. As discussed earlier, menses are caused by the presence of progesterone followed by its withdrawal.

Answer 20

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Question 21

M. test. If bleeding occurs (i.e., positive progesterone withdrawal test), it means???

Answer 21

It means estrogen levels are normal and the endometrial lining builds up just fine, and that anovulation is the cause of the irregular menses.

Question 22

M. test.

In PCOS, for instance, since we don’t have a corpus luteum and progesterone secretion, we don’t have the sequence of “progesterone present followed by withdrawal,” so we can’t get regular menses. However, since estrogen levels are normal in PCOS, the endometrial lining can grow without a problem, so if progesterone is given exogenously, followed by its withdrawal, we will see bleeding.

Answer 22

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Question 23

M. test.

In conditions like Turner (where estrogen is low) or Asherman (scarred uterus that can’t grow), giving progesterone won’t induce bleeding since the endometrial lining hasn’t developed.

The bleeding will only occur if estrogen is present in normal amounts to allow for endometrial growth, where the administration, followed by withdrawal, of exogenous progesterone essentially induces forced menses.

Answer 23

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