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 Prerenal vs Intrarenal(ATN) BUN:Cr Ratio  



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Author4 Posts
  #1

In Prerenal Azotemia, the BUN: Cr ratio is > 20
In Intrarenal or ATN, the BUN: Cr ratio is <10

WHY??? What causes this?




  #2

in prerenal RF the kidney reabsorptive power is preserved>>>in this situatiom the kidney attempts to increase body fluids by increasing reabsorption of BUN.

in intrarenal RF the kidney can nt reabsorb BUN....as the problem is in the tubular cells.


in both conditions the Cr reabsorpion is not changed ( i dont know why )



that what i know .......hpoe this help cool


  #3

dr.wad wrote:
in prerenal RF the kidney reabsorptive power is preserved>>>in this situatiom the kidney attempts to increase body fluids by increasing reabsorption of BUN. in intrarenal RF the kidney can nt reabsorb BUN....as the problem is in the tubular cells. in both conditions the Cr reabsorpion is not changed ( i dont know why ) that what i know .......hpoe this help cool


Yes, thats how I remember it too:

In prerenal: Body thinks dehydration so it HOLDS ON to H20, Na, and BUN. So there is an INCREASE in BUN. BUN:Cr ratio > 20

In intrarenal: Kidney problem, so can't reab. Na, and can't reab BUN, so DECREASED BUN. BUN: Cr ratio < 10

But, what I can't remember is.. WHY is BUN only involved but NOT creatinine?


  #4

Because the Creat clearance for all the practical purposes is close to 1. so almost everything is excreted & the remaining is Secreted,there is no reabsorption.so If the Kidneys are functioning well, it will be cleared unless there is severe dehydration in which Creat levels will rise as well.
Hope this helps.






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