ATN elevated or decreased BUN: Cr? Error in Pathoma?

[Jonari]

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On page 126 when talking about ATN, at bullet point C - Dr. Sattar says that there is decreased BUN:Cr because epithelium isn't intact so we're not reabsorbing - makes sense.

On the next page, at bullet point E - he mentions there is elevated B:C?

Not sure what I'm missing here...😕

 

[withrye]

Decreased ratio of BUN:Cr, but both are increased in absolute numbers. If normal is 15:1, the new numbers for ATN might be 30:3. The ratio is now 10:1, but the absolute numbers have gone up.

 

[Jonari]

Decreased ratio of BUN:Cr, but both are increased in absolute numbers. If normal is 15:1, the new numbers for ATN might be 30:3. The ratio is now 10:1, but the absolute numbers have gone up.

Crap, you're right. I read it wrong...goodness, I need to slow down and read better. Can you give your input on the old thread I bumped up about the myglobin/crush injury, please? Thanks.

 

[FIREitUP]

Crap, you're right. I read it wrong...goodness, I need to slow down and read better. Can you give your input on the old thread I bumped up about the myglobin/crush injury, please? Thanks.

i think it's the same concept. you are filtering much less, but the amount that you are filtering is getting less reabsorbed, thus you have a large FeNa. Since your GFR is decreased, you get a buildup of solutes in the blood and an increase in TBNa and TBH2O. Don't hold me to this, though, I just started studying renal path yesterday haha