Few qs + mnemonic

Discussion in 'Step I' started by medstu2006, May 28, 2008.

  1. medstu2006

    medstu2006 Senior Member

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    I have 2 questions from the Endocrine system.

    How does Cushing's syndrome lead to amenorrhea?

    21-alpha-hydroxylase def is the most common adrenal steroid def. It causes female pseudohermaphroditism. Now, even 11-beta-hydroxylase def also dec testosterone levels. So does 11-beta-hydroxylase def also cause female pseudohermaphroditism? I think it does, but it doesn't specifically state in FA p.277. What do you think?

    Mnemonic:
    I've made a mnemonic for the primary brain tumors on FA p. 392.

    Adult peak incidence:
    Glia's Men Show (Schwannoma) Oligo's Pit.
    I couldn't come up with something better. If someone has a better mnemonic, let me know.

    Childhood peak incidence:
    Pile the Medulla UpIn (Epen.-Ependymoma) He-man's Cranium.
     
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  3. agranulocytosis

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    It does. The block will cause the substrates proximal to block to all increase and result in an adrenogenital syndrome.

    As for Cushing's, I believe only Cushing's Disease causes amenorrhea because of excessive ACTH from the pituitary, but Syndrome due to exogenous corticosteriods won't cause amenorrhea.
     
  4. TRKATK

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    How does excess acth cause amenorrhea.. trying to think this one through
     
  5. alpha06

    alpha06 Senior Member
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    Mechanism is like that of PCOS (In Cushing's, you have increased androgen levels):

    http://www.emedicine.com/MED/topic2173.htm

    "A proposed mechanism for anovulation and elevated androgen levels suggests that, under the increased stimulatory effect of luteinizing hormone (LH) secreted by the anterior pituitary, stimulation of the ovarian theca cells is increased. In turn, these cells increase the production of androgens (eg, testosterone, androstenedione). Because of a decreased level of follicle-stimulating hormone (FSH) relative to LH, the ovarian granulosa cells cannot aromatize the androgens to estrogens, and this inability leads to decreased estrogen levels and consequent anovulation."


    11BH def does not cause a decrease in testosterone, therefore it does not cause female pseudohermaphrodism. Look at the diagram more closely...
     
  6. medstu2006

    medstu2006 Senior Member

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    Inc ACTH would inc estrogen levels also, inhibiting LH, FSH.
     
  7. medstu2006

    medstu2006 Senior Member

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    11BH def causes inc in testosteone. Female pseudohermaphrodism is a result of high testosterone levels.
     
  8. agranulocytosis

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    The ACTH will overstimulate the zona fasiculata and reticularis, with the reticularis producing the adrenal androgens. It's similar to the adrenogenital syndromes in that excessive production of adrenal androgens will result in virilization in females and precocious puberty in males.
     
  9. TRKATK

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    thanks that made sense guys!:thumbup:

    but wiki says "Cushing's Disease/Syndrome can also cause amenorrhoea due to excessive amounts of cortisol in the blood stream."

    -what would be the mechanism of that?

    I would think excessive cortisol feedsback and :. shuts off acth :. no overstimulation of the adrenal cortex.
     
  10. Lany

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    Amennorhea in this matter is due to "increase in androgens" not specific to ACTH even though high ACTH results in increasing androgens.

    1) cushing disease (pit. adenoma) - (inc. ACTH)
    2) ectopic acth (from small cell ca.) - (inc. ACTH)
    3) primary adrenal hyperplasia - (dec. ACTH)
    4) anabolic steriods (dec. ACTH)

    .. can cause virilization -> amenorrhea

    Exogenous glucocorticosteriods (dec. ACTH) - no virilization? (not sure on this)

    1) androgens interfere with normal follicular development and ovulation altering the normal hormonal profile of the menstrual cycle.

    2) androgens are converted to estrogens by aromatase (in fat), however, the failure to develop a follicle and te subsequent corpus luteum at the ovulation eliminates progesterone production and eventual withdrawal bleeding when the corpus luteum regresses. High levels of androgen may cause endometrial atrophy. (http://www.mcl.tulane.edu/ob-gyn/clinical/reproendo/amenorrhea1.pdf)
     
  11. Lany

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    generalizing alot here.

    estrogen stimulates/inhibits LH/FSH at diff. phases while progesterone plays a role under the ACTH tree also counteracting it.

    Female pseudohermaphrodism is caused by increase in androgens at fetal period (by mother or fetus) and its rare. And logically, it is possible under both 21, and 11 def.
     
  12. agranulocytosis

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    Agreed :thumbup: I was just answering the OP's question specific to Cushing's.

    As for Syndrome vs Disease, this is my reasoning: cortisol's effects are primarily on blood glucose, sodium/potassium balance, immune function, increasing sensitivity to catecholamines, etc. I really don't recall anything regarding sex hormones being directly controlled by cortisol. However, we do know that Cushing's is associated with hirsuitism and virilization, so the only way I can correlate the two is the incidental correlation between ACTH and increased sex hormones (via Disease).

    But I could just be talking out of my ass and I missed something real big about this subject, so who knows. Plus, I doubt anything this detailed is really that significant, especially when the main diagnostic effect of excessive ACTH is hyperpigmentation.
     

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