FENa question

[tomtom1287]

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Hey guys,
This is a question from kaplan qbank.
can some one please explain why fractional excretion of filtered na is increased in this situation with reduced gfr where there is no increase in urine Na excretion? Wouldn't urine na excretion increase when there is an increase in FENa?

Thanks for the help

 

[shouldigomd]

Where does it say no increase of urine Na? I saw no mention of urine Na... only FENa.

Renal insufficiency you can almost always assume elevated FENa which is a marker for renal problems. Reduced GFR further backs the point.

 

[tomtom1287]

Where does it say no increase of urine Na? I saw no mention of urine Na... only FENa.

Renal insufficiency you can almost always assume elevated FENa which is a marker for renal problems. Reduced GFR further backs the point.

sorry, that part was cropped out. please look at option E

 

[hbslax4]

His GFR is down and so he also has lower urine output so he may not be excreting more Na+ overall, however he likely has ATN so we can clearly say the proportion of filtered Na being excreted (FENa) is increased. Hopefully that makes sense.


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[GODinyou99er]

"For ease of recall, one can just remember the fractional excretion of sodium is the clearance of sodium divided by the glomerular filtration rate (i.e. the "fraction" excreted)."- WIKI

DECREASE GFR....INCREASE Fe NA

 

[tomtom1287]

"For ease of recall, one can just remember the fractional excretion of sodium is the clearance of sodium divided by the glomerular filtration rate (i.e. the "fraction" excreted)."- WIKI

DECREASE GFR....INCREASE Fe NA

In Pre renal failure, there is decreased GFR but decreased FENa as well. I'm a bit confused

 

[shouldigomd]

In Pre renal failure, there is decreased GFR but decreased FENa as well. I'm a bit confused

In pre-renal failure the kidney itself is not damaged. Prolonged dehydration can result in eventual kidney damage (ATN) and FENa will increase