BUN:Cr in Contrast-induced nephropathy

[Metaform]

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Labs for contrast nephropathy resemble that of prerenal azotemia, does that also mean the BUN:Cr in contrast nephropathy is also >20? would seem so right? seems to me even though its a cause of ATN, all the labs including BUN:Cr should look like prerenal azotemia

 

[ASAPRocky]

ya.

but in board exams, and in real life, i have never used the BUN:Cr ratio and have never had a problem.

 

[NRAI2001]

Labs for contrast nephropathy resemble that of prerenal azotemia, does that also mean the BUN:Cr in contrast nephropathy is also >20? would seem so right? seems to me even though its a cause of ATN, all the labs including BUN:Cr should look like prerenal azotemia

I thought that the dye causes pre-renal vasoconstriction that later leads to ATN? Gonna have to look that up... good question

 

[Metaform]

afferent arteriole vasoconstriction = hypoperfusion = the very definition of prerenal azotemia.

i just wanted to confirm if the BUN:Cr values are the same since google failed me. on another note I think BUN:Cr are quite helpful in solving questions because they help you narrow down the DDx somewhat.

Actually I think trying to classify these things is a double edged sword that can be helpful yet also be paradoxical pain in the ass b/c NSAID induced nephropathy can technically be any one of those. According to MTB , NSAIDs also cause AIN minus the eosinophills, but are also a cause of pre renal azotemia, and ATN. so wtf

 

[Myxedema]

In order to have a BUN/Cre ratio of >20, there must be adequate proximal tubule function. Since contrast material damages the proximal tubule, BUN/Cre would be <20.