1. This forum is for support and discussion only. Please promote test prep materials/services (including AMAs) in the Special Offers subforum only. Thanks!
    Dismiss Notice

NBME 3 is evil

Discussion in 'Step I' started by BrisketAttack, Jun 1, 2008.

  1. BrisketAttack

    2+ Year Member

    Joined:
    Jun 1, 2008
    Messages:
    199
    Likes Received:
    0
    Status:
    Medical Student
    This question on NBME 3 has me going nuts:

    What will increase serum aldosterone concentration in an experimental subject?

    -administration of ACE inhibitor
    -increased Na intake
    -inhibiting ACTH secretion
    -IV 0.9% saline
    -Water restriction

    Any help would be greatly appreciated.
     
  2. Jbienven

    Jbienven Senior Member
    7+ Year Member

    Joined:
    Oct 7, 2004
    Messages:
    178
    Likes Received:
    0
    Status:
    Resident [Any Field]


    I just took the stupid thing. I put water restriction.
     
  3. BrisketAttack

    2+ Year Member

    Joined:
    Jun 1, 2008
    Messages:
    199
    Likes Received:
    0
    Status:
    Medical Student
    I put the same answer, but I don't understand the mechanism at all. It just sounded good. That's not gonna cut it on the real exam. i just got lucky.
     
  4. DragonWell

    Moderator Emeritus 10+ Year Member

    Joined:
    Nov 20, 2004
    Messages:
    1,682
    Likes Received:
    9
    Status:
    Attending Physician
    I can see the water restriction-> hypovolemia-> inc aldosterone reasoning, but I also think that technically the answer could be the ACE. I think Goljan even talks about "aldosterone escape" in patients on an ACE...eventually the aldosterone "breaks through", which is why an ACE + spironolactone is better than just an ACE. I don't know if this is specific to CHF or universal w/ ACE therapy, though.

    This may be reading into the question, though.

    http://www.medscape.com/viewarticle/521164_3
     
  5. VPDcurt

    VPDcurt 2K Member
    10+ Year Member

    Joined:
    Jul 20, 2004
    Messages:
    2,644
    Likes Received:
    23
    Status:
    Attending Physician
    It's definitely water restriction and not an ACE. Mineralocorticoid escape generally occurs in the presence of ECF volume expansion - a condition not stated or even remotely suggested by the simple stem of this question. A major stimulus for aldosterone secretion is the RAA via decreased blood volume.
     
  6. Mr. Freeze

    Mr. Freeze Not right. (in the head)
    10+ Year Member

    Joined:
    Apr 22, 2005
    Messages:
    1,355
    Likes Received:
    2
    Status:
    Resident [Any Field]
    Think I got tripped up because at the time I didn't see much difference between water restriction and increased salt intake. Got some work to do I guess.
     
  7. osli

    osli Senior Member
    5+ Year Member

    Joined:
    Oct 13, 2005
    Messages:
    1,279
    Likes Received:
    6
    Status:
    Medical Student
    Aldosterone retains salt... not what you want if you've eaten too much of it. Increased salt intake would decrease aldosterone levels.

    The reason it rises in hypovolemia (after water deprivation) is that by retaining salt you also retain water, helping to offset the low-volume situation that triggered the aldosterone release.
     
  8. Mr. Freeze

    Mr. Freeze Not right. (in the head)
    10+ Year Member

    Joined:
    Apr 22, 2005
    Messages:
    1,355
    Likes Received:
    2
    Status:
    Resident [Any Field]
    I looked at it, incorrectly, like decreasing water would increase relative [Na] and I guess failed to see the volume component of renin regulation. In looking at it now, what I did was confuse the macula densa mechanism with renin regulation. Just giving away points. ****!!!!!!!!:mad:
     
  9. MAO

    MAO

    Joined:
    Jun 1, 2008
    Messages:
    2
    Likes Received:
    0
    Status:
    Medical Student
    increased Na+ intake -->cause hypervolemia -->inhibit renin and increase ANP

    water restriction -->hypovolemia-->activate renin angiotensin system --> increase aldosterone
     
  10. hippocampus

    hippocampus Senior Member
    5+ Year Member

    Joined:
    Jun 4, 2005
    Messages:
    286
    Likes Received:
    0
    what is aldosterone escape?

    what MAO wrote, it this all happening in the ECF compartment?
     
  11. DragonWell

    Moderator Emeritus 10+ Year Member

    Joined:
    Nov 20, 2004
    Messages:
    1,682
    Likes Received:
    9
    Status:
    Attending Physician
    The way I understand it, there are actually two definitions. In a pt with Conn's Syndrome, aldosterone escape refers to the fact that even with greatly increased aldosterone levels, the BP will stabilize at an elevated level due to natriuresis. This definition is explained here.

    The other definition which is the one that I mentioned in the post above has to due with the fact that even though patients are put on an ACE, it is possible for their aldosterone levels to eventually increase in spite of the med.

    Nice explanation here.
     
  12. MAO

    MAO

    Joined:
    Jun 1, 2008
    Messages:
    2
    Likes Received:
    0
    Status:
    Medical Student
    increased Na+ intake--> increased Na+ filtered in the bowmans space (increased Na+ load) -->70% of it is reabsorbed in PCT ( since amount filtered is more ,the AMOUNT reabsorbed is also more, though % reabsorbed is still 70%) -->along with it water is also reabsorbed -->ECF volume increase.

    i hope now it makes sense.........................
     

Share This Page