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Chronic renal failure

Discussion in 'Step I' started by aspiringmd1015, Jul 28, 2015.

  1. aspiringmd1015

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    why does po4 build up, but ca2+ become lower? simply just bc of vitamin D? but that would effect both ca2+ and po4 absorption in the gut. why is ca2+ being preferentially lost in the urine and gut? could it be bc you cant secrete + so you lose the paracellular absorption of ca2+ in the TAL?
     
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  3. pathologyDO

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    Po4 binds calcium in serum. You lose serum free calcium when phosphate levels increase. Is there another reason? Maybe, but that's one explanation
     
  4. aspiringmd1015

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    right, drives it into tissues, mets calcification and the whole shish kabob, so in that case ca2+ and po4 would both have to be high initially, adn then po4 would lower serum ca2+, but with CRF you lose vit D activation, so you should be losing po4 in your gut along w/ca2+
     
  5. pathologyDO

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    You also lose the ability to excrete phosphate, so although you take up less in the gut the degree of decreased excretion is greater, so phosphate is still high
     
  6. aspiringmd1015

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    where in the tubules is p04 excreted? i know most i think 85% of po4 is reabsorbed in the PCT, but dont know where its excreted
     
  7. aspiringmd1015

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    side question: what's the stimulus for EPO release? is it hypoxia, hypoxemia, or what?
     

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