Nephrogenic Diabetes Insipidus & Lithium & Diuretic Confusion! - USMLE Forums
USMLE Forums Logo
USMLE Forums         Your Reliable USMLE Online Community     Members     Posts
Home
USMLE Articles
USMLE News
USMLE Polls
USMLE Books
USMLE Apps
Go Back   USMLE Forums > USMLE Step 1 Forum

USMLE Step 1 Forum USMLE Step 1 Discussion Forum: Let's talk about anything related to USMLE Step 1 exam


Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 05-22-2012
numbndumb's Avatar
USMLE Forums Master
 
Steps History: 1+CK+CS+3
Posts: 529
Threads: 57
Thanked 284 Times in 152 Posts
Reputation: 294
Kidney Nephrogenic Diabetes Insipidus & Lithium & Diuretic Confusion!

hi guys, i m so totally confused about this.

First of all Lithium causes nephrogenic diabetes insipidus right? Then i read somewhere that prolonged use of thiazides and loop diuretics impairs lithium clearance hence causing it to accumulate.

Then again i read that hydrochlorthiazide is used to treat nephrogenic diabetes insipidus????? This is where my brain failed to think any more. I just dont get it. Please help me clear this concept people! thanks
Reply With Quote Quick reply to this message



  #2  
Old 05-22-2012
USMLE Forums Veteran
 
Steps History: 1+CK+CS
Posts: 257
Threads: 49
Thanked 75 Times in 50 Posts
Default

True Lithium causes DI and it is treated with amiloride.
Its also true that chronic loops n thiazides can cause Lithium toxicity,both of them are 2 separate things!

And yes Nephrogenic DI is treated with Thaizides, as far as i remember from what raymon said, in the beginning there will be loss of Na and water, but then Aldosterone senses it(the loss in water n Na) and starts reabsorbing more Na and water and so treats Nephrogenic DI. (Correct me if i am wrong!)
Reply With Quote Quick reply to this message
The above post was thanked by:
numbndumb (05-22-2012)
  #3  
Old 05-22-2012
USMLE Forums Master
 
Steps History: 1+CK+CS
Posts: 1,406
Threads: 118
Thanked 647 Times in 409 Posts
Reputation: 657
Default

Quote:
Originally Posted by vna.rao22 View Post
True Lithium causes DI and it is treated with amiloride.
Its also true that chronic loops n thiazides can cause Lithium toxicity,both of them are 2 separate things!

And yes Nephrogenic DI is treated with Thaizides, as far as i remember from what raymon said, in the beginning there will be loss of Na and water, but then Aldosterone senses it(the loss in water n Na) and starts reabsorbing more Na and water and so treats Nephrogenic DI. (Correct me if i am wrong!)
oh so thiazides help diabetes insipidus by basically stimulating aldosterone to make up for the defect in adh action?
ive never really understood why thiazides help in nephrogenic diabetes insipidus.
__________________
"inflammable means flammable!? What a country."
Reply With Quote Quick reply to this message
The above post was thanked by:
numbndumb (05-22-2012)
 
  #4  
Old 05-22-2012
USMLE Forums Master
 
Steps History: 1+CK+CS
Posts: 1,406
Threads: 118
Thanked 647 Times in 409 Posts
Reputation: 657
Default

Quote:
Originally Posted by numbndumb View Post
First of all Lithium causes nephrogenic diabetes insipidus right? Then i read somewhere that prolonged use of thiazides and loop diuretics impairs lithium clearance hence causing it to accumulate.
lithium acts like Na+
so we dont want to give a loop that acts on the PCT because thats where most Na+ is reabsorbed, and we will see a reabsorption of lithium too.
hence, do not use thiazides.

what we do want to use is a K+-sparing diuretic, since it acts on the PCT.
the drug of choice is umm amiloride i think.
__________________
"inflammable means flammable!? What a country."
Reply With Quote Quick reply to this message
  #5  
Old 05-22-2012
USMLE Forums Addict
 
Steps History: Not yet
Posts: 114
Threads: 23
Thanked 20 Times in 18 Posts
Reputation: 39
Default

lithium cause dame to the tubule so net result is nephrogenic diabetes the treatment is by thiazide hydrochlorthiazides why? bcz it makes the urine hyperosmolar by increase excretion of electrolyte( lead to hyporkalemia hypoantremia hypomagnesiia so the urine become hyperosmolar concetrated so ir will decrease from 11 L to 3 liters
Reply With Quote Quick reply to this message
  #6  
Old 05-22-2012
USMLE Forums Master
 
Steps History: 1+CK+CS
Posts: 1,406
Threads: 118
Thanked 647 Times in 409 Posts
Reputation: 657
Default

Quote:
Originally Posted by cage92 View Post
lithium cause dame to the tubule so net result is nephrogenic diabetes the treatment is by thiazide hydrochlorthiazides why? bcz it makes the urine hyperosmolar by increase excretion of electrolyte( lead to hyporkalemia hypoantremia hypomagnesiia so the urine become hyperosmolar concetrated so ir will decrease from 11 L to 3 liters
i have no idea what you just said but it sounds right because in my FA i have annotated "increases urine concentraion".

i dont see how its making the urine concentrated though if its reabsorbing sodium, and calcium.

loops dont reabsorb calcium so shouldnt they be better at concentrating the urine?
__________________
"inflammable means flammable!? What a country."
Reply With Quote Quick reply to this message
  #7  
Old 05-22-2012
numbndumb's Avatar
USMLE Forums Master
 
Steps History: 1+CK+CS+3
Posts: 529
Threads: 57
Thanked 284 Times in 152 Posts
Reputation: 294
Default

Quote:
Originally Posted by Dr.NickRiviera View Post
lithium acts like Na+
so we dont want to give a loop that acts on the PCT because thats where most Na+ is reabsorbed, and we will see a reabsorption of lithium too.
hence, do not use thiazides.

what we do want to use is a K+-sparing diuretic, since it acts on the PCT.
the drug of choice is umm amiloride i think.
I thought loops acted on the thick ascending limb of the loop and thiazides on the DCT and K sparing in the collecting ducts???

this whole thing is so crazy! lol
Reply With Quote Quick reply to this message
  #8  
Old 05-22-2012
USMLE Forums Addict
 
Steps History: Not yet
Posts: 135
Threads: 3
Thanked 73 Times in 48 Posts
Reputation: 83
Default

Quote:
lithium acts like Na+
so we dont want to give a loop that acts on the PCT because thats where most Na+ is reabsorbed, and we will see a reabsorption of lithium too.
hence, do not use thiazides.

what we do want to use is a K+-sparing diuretic, since it acts on the PCT.
the drug of choice is umm amiloride i think.
what?

Quote:
I thought loops acted on the thick ascending limb of the loop and thiazides on the DCT and K sparing in the collecting ducts???
that's the way I remember it too.
__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
You can't confuse the confused!
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Reply With Quote Quick reply to this message
The above post was thanked by:
mycoplasma (05-22-2012)
  #9  
Old 05-22-2012
USMLE Forums Master
 
Steps History: 1+CK+CS
Posts: 1,406
Threads: 118
Thanked 647 Times in 409 Posts
Reputation: 657
Default

yea, thiazides do work in the DCT. i dont know why i said PCT.

you know what, diuretics inhibit sodium reabsorption, so why do any even cause a problem with lithium then.
hmm i dont know why i have that written down in my book.

ok, yea i have no idea why we cant use loops or thiazides but we prefer to use amiloride.

good thing i came across this thread, now i can know the truth!

anybody know?

so far all i know is lithium acts like sodium, and the DOC for lithium-induced nephrogenic diabetes insipidus is amiloride.
__________________
"inflammable means flammable!? What a country."
Reply With Quote Quick reply to this message
  #10  
Old 05-22-2012
numbndumb's Avatar
USMLE Forums Master
 
Steps History: 1+CK+CS+3
Posts: 529
Threads: 57
Thanked 284 Times in 152 Posts
Reputation: 294
Default

Quote:
Originally Posted by Dr.NickRiviera View Post
yea, thiazides do work in the DCT. i dont know why i said PCT.

you know what, diuretics inhibit sodium reabsorption, so why do any even cause a problem with lithium then.
hmm i dont know why i have that written down in my book.

ok, yea i have no idea why we cant use loops or thiazides but we prefer to use amiloride.

good thing i came across this thread, now i can know the truth!

anybody know?

so far all i know is lithium acts like sodium, and the DOC for lithium-induced nephrogenic diabetes insipidus is amiloride.
yeah i thought amiloride was the DOC for lithium induced DI too but i came across this question in UW where they said the appropriate management is stop the lithium n give hydrochlorthiazide! thats so weird right?
Reply With Quote Quick reply to this message
  #11  
Old 05-22-2012
USMLE Forums Master
 
Steps History: 1+CK+CS
Posts: 1,406
Threads: 118
Thanked 647 Times in 409 Posts
Reputation: 657
Default

Quote:
Originally Posted by numbndumb View Post
yeah i thought amiloride was the DOC for lithium induced DI too but i came across this question in UW where they said the appropriate management is stop the lithium n give hydrochlorthiazide! thats so weird right?
whats the question ID
__________________
"inflammable means flammable!? What a country."
Reply With Quote Quick reply to this message
  #12  
Old 05-22-2012
numbndumb's Avatar
USMLE Forums Master
 
Steps History: 1+CK+CS+3
Posts: 529
Threads: 57
Thanked 284 Times in 152 Posts
Reputation: 294
Default

Quote:
Originally Posted by Dr.NickRiviera View Post
whats the question ID
umm im doing UW(2009) offline so i dnt knw the question ID. Im thinking may be they got rid of this question now!
Reply With Quote Quick reply to this message
  #13  
Old 05-22-2012
USMLE Forums Master
 
Steps History: 1+CK+CS
Posts: 1,406
Threads: 118
Thanked 647 Times in 409 Posts
Reputation: 657
Default

Quote:
Originally Posted by numbndumb View Post
umm im doing UW(2009) offline so i dnt knw the question ID. Im thinking may be they got rid of this question now!
yea ive gone through uworld 1.5x and i dont remember such a question
they must have removed it.

thiazides are the treatment for nephrogenic diabetes insipidus, i agree.
but for lithium-induced nephrogenic diabetes insipidus, im pretty sure the DOC is amiloride.

why? i dont know lol.
__________________
"inflammable means flammable!? What a country."
Reply With Quote Quick reply to this message
  #14  
Old 05-23-2012
numbndumb's Avatar
USMLE Forums Master
 
Steps History: 1+CK+CS+3
Posts: 529
Threads: 57
Thanked 284 Times in 152 Posts
Reputation: 294
Default

Quote:
Originally Posted by Dr.NickRiviera View Post
yea ive gone through uworld 1.5x and i dont remember such a question
they must have removed it.

thiazides are the treatment for nephrogenic diabetes insipidus, i agree.
but for lithium-induced nephrogenic diabetes insipidus, im pretty sure the DOC is amiloride.

why? i dont know lol.
LOL, yeah that's what ive concluded too!
Reply With Quote Quick reply to this message
  #15  
Old 05-23-2012
USMLE Forums Scout
 
Steps History: Step 1 Only
Posts: 17
Threads: 0
Thanked 14 Times in 11 Posts
Reputation: 24
Default

Amiloride blocks the ENaC-channels, preventing Lithium from being trapped within the collecting duct cells causing further damage. At least that's how I understand it.
Reply With Quote Quick reply to this message



  #16  
Old 05-23-2012
USMLE Forums Addict
 
Steps History: Not yet
Posts: 135
Threads: 3
Thanked 73 Times in 48 Posts
Reputation: 83
Default

Quote:
Amiloride blocks the ENaC-channels, preventing Lithium from being trapped within the collecting duct cells causing further damage. At least that's how I understand it.
Lithium and Na+ are both reabsorbed in the distal tubules/collecting ducts via the ENaC channels. So when amiloride blocks ENaC, wouldn't that mean both Na+ and Li+ would increase in the lumen?
__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
You can't confuse the confused!
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Reply With Quote Quick reply to this message
  #17  
Old 05-23-2012
USMLE Forums Scout
 
Steps History: Step 1 Only
Posts: 17
Threads: 0
Thanked 14 Times in 11 Posts
Reputation: 24
Default

The collecting duct cells have ENaC channels and a basolateral sodium pump, which Lithium does not act on. Just like in excitable tissue: Lithium mimics the role of sodium by permeating the sodium channels, but they're not pumped out by the Na/K-ATPase, and accumulate inside the cell.

EDIT:
I suppose the rest of the mechanism is the same: sodium (and lithium) initially lost in urine –> ECF volume contraction –> increased oncotic pressure in peritubular capillaries –> increased proximal reabsorption of sodium and consequently also water.

Does that sound reasonable?

Last edited by Romaeus; 05-23-2012 at 07:41 AM.
Reply With Quote Quick reply to this message
  #18  
Old 05-23-2012
USMLE Forums Addict
 
Steps History: Not yet
Posts: 114
Threads: 23
Thanked 20 Times in 18 Posts
Reputation: 39
Default

guys why you are confused i gave you the correct answer and i am sure
Reply With Quote Quick reply to this message
  #19  
Old 05-23-2012
USMLE Forums Addict
 
Steps History: Not yet
Posts: 135
Threads: 3
Thanked 73 Times in 48 Posts
Reputation: 83
Default

Quote:
First of all Lithium causes nephrogenic diabetes insipidus right? Then i read somewhere that prolonged use of thiazides and loop diuretics impairs lithium clearance hence causing it to accumulate.

Then again i read that hydrochlorthiazide is used to treat nephrogenic diabetes insipidus????? This is where my brain failed to think any more. I just dont get it. Please help me clear this concept people! thanks
Well I ended up looking this up, cuz it was bothering me just a lil bit.

What I got was that Li+ and Na+ are very similar. They're both mostly absorbed in the the proximal tubules via the same channels. In normal circumstances only a little Li+ is reabsorbed in the distal tubules, using the ENaC that normally absorbs Na+. While the Na+ reabsorbed by this channel is pumped out using the Na+/K+ ATPase at the basolateral membrane, the Li+ reabsorbed uses the Na+/H+ exchanger to get out of the cell.

Prolonged thiazides block the reabsorption of Na+/Cl- in the distal tubule, so the decrease in [Na+] in serum would eventually increase reuptake of Na+ in the proximal tubule, coincidentally this would also result in an increased reabsorption of Li+ in the proximal tubules. Consequently there'll be accumulation of Li+ in the serum which worsens lithium toxicity if already present (lithium toxicity is too much lithium in blood)

But, if the patient has lithium induced DI (where lithium is damaging the principal cells of the late nephron), thiazides by indirectly increasing Li+ reabsorption in the proximal tubule would result in decreased Li+ reaching the distal tubules/collecting ducts. This would mean decreased reaborption of lithium in the late distal tubule/collecting ducts, and less damage to those cells by lithium.

Basically amiloride acts the same way, inhibiting absorption of lithium in the late part of the nephron.

Hope that helps, and please correct any mistakes.
__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
You can't confuse the confused!
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Reply With Quote Quick reply to this message
The above post was thanked by:
numbndumb (05-23-2012)
  #20  
Old 05-23-2012
numbndumb's Avatar
USMLE Forums Master
 
Steps History: 1+CK+CS+3
Posts: 529
Threads: 57
Thanked 284 Times in 152 Posts
Reputation: 294
Default

Quote:
Originally Posted by slowpoke View Post
Well I ended up looking this up, cuz it was bothering me just a lil bit.

What I got was that Li+ and Na+ are very similar. They're both mostly absorbed in the the proximal tubules via the same channels. In normal circumstances only a little Li+ is reabsorbed in the distal tubules, using the ENaC that normally absorbs Na+. While the Na+ reabsorbed by this channel is pumped out using the Na+/K+ ATPase at the basolateral membrane, the Li+ reabsorbed uses the Na+/H+ exchanger to get out of the cell.

Prolonged thiazides block the reabsorption of Na+/Cl- in the distal tubule, so the decrease in [Na+] in serum would eventually increase reuptake of Na+ in the proximal tubule, coincidentally this would also result in an increased reabsorption of Li+ in the proximal tubules. Consequently there'll be accumulation of Li+ in the serum which worsens lithium toxicity if already present (lithium toxicity is too much lithium in blood)

But, if the patient has lithium induced DI (where lithium is damaging the principal cells of the late nephron), thiazides by indirectly increasing Li+ reabsorption in the proximal tubule would result in decreased Li+ reaching the distal tubules/collecting ducts. This would mean decreased reaborption of lithium in the late distal tubule/collecting ducts, and less damage to those cells by lithium.

Basically amiloride acts the same way, inhibiting absorption of lithium in the late part of the nephron.

Hope that helps, and please correct any mistakes.
great! thanks for that
Reply With Quote Quick reply to this message



Reply

Tags
Pathology-, Pharmacology-, Renal-

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the USMLE Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Medical School
Choose "---" if you don't want to tell. AMG for US & Canadian medical schools. IMG for all other medical schools.
USMLE Steps History
What steps finished! Example: 1+CK+CS+3 = Passed Step 1, Step 2 CK, Step 2 CS, and Step 3.

Choose "---" if you don't want to tell.

Favorite USMLE Books
What USMLE books you really think are useful. Leave blank if you don't want to tell.
Location
Where you live. Leave blank if you don't want to tell.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
Hypokalemia and nephrogenic diabetes inspidus? aiminghigh USMLE Step 2 CK Forum 1 04-06-2012 10:10 AM
Why we use a diuretic in nephrogenic DI! drmdshah USMLE Step 1 Forum 3 06-09-2011 02:04 PM
Diabetes Insipidus Diagnosis jackat1000 USMLE Step 1 Mnemonics 0 07-25-2010 09:57 AM
Treatment for nephrogenic diabetes insipidus? lemontea88 USMLE Step 1 Forum 8 04-07-2010 07:33 AM

RSS Feed
Find Us on Facebook
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.

USMLE® & other trade marks belong to their respective owners, read full disclaimer
USMLE Forums created under Creative Commons 3.0 License. (2009-2014)