NBME 22 Answers : Block 3 : #29 = A 45-year-old man with end-stage renal failure is ...

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submitted by skraniotis(6),

Undialyzed renal failure leads to metabolic acidosis, and as a result bicarb gets depleted as it tries to buffer the accumulation of organic acids.

bubbles Thanks for the explanation! Do you know why Mg would not be a potential answer? Phosphate also accumulates in those with undialyzed renal failure, so I was thinking that maybe magnesium as a divalent cation would complex with PO3 (in a mechanism similar to Ca). +

nwinkelmann From the little bit of research I just did (because I didn't learn anything about dialysis at my medical school), ESRD can be associated with either low or high Mg levels, so the dialysate can cause either increased or decreased Mg levels depending on the patient's serum content, therefore I don't think based on this question, would could determine if removal of dialysis would lead to elevated or decreased magnesium. The end of the first article seems to favor ESRD leading to hypermagnesemia, so if that's the case, then removal of dialysis would cause Mg to increase as well. https://www.karger.com/Article/FullText/452725 and https://www.karger.com/Article/FullText/485212 +1

hyperfukus why is it that we aren't learning this stuff and they r just throwing it on step there's barely a blurb in FA about ckd/eskd +

hyperfukus does uremia potentially have to do with this? +

medulla ESRD and not getting dialysis -> he is uremic -> met acidosis -> dec bic +2

angelaq11 @medulla this is the best and simplest explanation. I got it wrong and chose Mg, wish I had made that connection. +