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Old 06-13-2011
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Question Primary adrenal insuficiency and Darrow Yannet Diagram

Can some one explain why we also gain in ICF with loss of aldosterone?
see following fig.
I thought that with losing both salt and water it should remain same

Primary adrenal insuficiency and Darrow Yannet Diagram-photo2427.jpg
click image to enlarge
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Old 06-13-2011
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pretty simple actually, dec aldosterone means dec retention of Na and H2O right?

so what does that mean as far as your urine fluid is concerned? ur losing hypertonic urine (more Na in urine than H2O as compared to normal tonicity of the serum) and thats the same thing as saying Hyponatremia (dec Na in serum due to Inc loss in the Urine)

so remember this, Primary aldosterone insuffieciency is the same thing as? Addison's dx...

1) addison's 2) loops 3) 21-OH deficiency ......all = dec Plasma Osm

so since there is dec in Plasma Osm (part of ECF)....where do u think the water(which is drank etc) is going to displace? Thats right into the ICF from the ECF(from serum to into cells), why? ICF osmolarity is higher(has more Na) and H2O always moves from low osm to high osm to balance everything out......(its vice versa for solutes such in normal diffusion go from high conc to low conc with their gradient) but remember that normally there is NO diffusion of Na and Glucose in the ICF only in the compartments of ECF.....ONLY H2O and Urea can move in between ICF and ECF.....

also the height on that diagram = osmolarity and the width = fluid volume

hope I didn't totally confuse you.....haha
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Old 06-13-2011
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exactly u made more dificult for me as each prof do
anyway i appreciate it
urine blood urea 21 Oh etc...OMg
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let me take a second whack at it....

since serum osm is normally not changed in a normal person urinating this means that the urine is isotonic (equivalent loss of h2o and Na) as compared to serum

now since you have 2 compartments as far as body water is concerned:
A) ICF
B) ECF ---which is further divided into 1)vascular and 2)interstitial
**normally both of the ICF and ECF are in equilibrium, meaning that fluid doesn't move in or out of the compartments due to their equal Osmolarities, if you decrease osmolarity of one compartment the Fluid moves opposite....from low Osm to High OSM...(more on this below quoting your example)

Aldosterone fxn = reabsorb water + Na from urine in kidney

Aldosterone insufficiency = aldosterone not working meaning no reabsorption of water and Na from urine, the same thing as saying MORE LOSS of Na and water in urine (though Na loss > water loss)

now since Na loss is > water loss in urine this means that the urine is HYPERTONIC (more Na per water ratio) as compared to the serum, the same thing as saying that the Serum is Hypotonic (less Na per water) as compared to Urine....

since serum is more Hypotonic than urine and the reason is Increased Na loss > than water loss in urine.....so hypotonic serum = Hyponatremic serum (less Na in serum b/c you peed it out) AKA Decreased Serum (ECF) Osm.

FOR YOUR EXAMPLE
A) in this case you decrease Osm of ECF (same thing as saying more water per solute)....so naturally to equilibrate the water will move from ECF to ICF, from dec Osm to High ICF Osm, the movement of fluid is caused by a pathologic reason Primary Aldosterone insufficiency due to the fact that it decreases ECF/Serum Osm....

I mean I tried to baby this as much as I could, sorry if this is still going over your head! hope this helps
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Old 06-13-2011
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Quote:
Originally Posted by IKR123 View Post
exactly u made more dificult for me as each prof do
anyway i appreciate it
urine blood urea 21 Oh etc...OMg
What he meant by was urea, like Na is important in determining Osm, as is glucose (there is an equation: Osm= Na + glucose / 18 + urea/2.8)

21 Oh deficiency you will result in no aldosterone production.
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thanks Patel....I should have caught that, thanks for clarifying it though
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ok lemme see if i can make it any easier for u to understand this.
here we go...

ICF has more K....right? ok and
ECF has more Na, urea and glucose...

lets just look at ICF-K and ECF-Na

Normally Aldosterone retains Na and h2o and excretes K:
so now:

so When we don't have aldosterone and our ECF osmolarity will DECREASE cuz we aren't retaining Na whereas our ICF osmolarity will INCREASE cuz we havent excreted our K...so now..OSMOSIS comes into play: h20 goes from low solute concentration ---> high solute concentration

THEREFORE...our ICF volume increases

lemme know if this helped!!!!
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Old 06-14-2011
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ya that sounds nice but i m afraid i have not studied all electrolytes in detail
anyway somehow its pretty good explanation
but why in above diagram ICF volume osmolarity is going down? then

Last edited by INCOGNITO; 06-14-2011 at 11:43 AM.
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well that swhen you look at it as a whole... when i was explaining to u i was comparing the osmolarities of ICF and ECF and thats the reason why h2o will go from low to high but as a WHOLE the osmolarities will drop in both comparments.

get it!
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