Great series on the topic! I have one quick question - why is the phosphate level low in this syndrome? Is it due to vitamin D being suppressed from the high Ca (so intestinal reabsorption of phosphate is minimized)? Low PTH usually means less phosphate excretion by the kidneys - so that would bring phosphate levels up - but are the intestinal loses due to low vitamin D more prominent, so that overall we have low phosphate? Thanks for any info :)
Actually, PTH causes increased excretion of phosphate in the kidneys! I like to remember this with thinking of PTH as Phosphate Trashing Hormone (got that from the Clinical Problem Solvers!)
@@decodingdx8285 Hello! Thanks for the response! Yes, that's what I thought: PTH = promotes phosphate excretion via kidneys, so a LOW PTH state (like in this syndrome) it would mean LESS phosphate excretion, right? So the low phosphate in this syndrome comes from decreased reabsorption in the GI tract due to low vitamin D, correct?
@@tszlachetka Thank you for so gently correcting me, as I misread your initial question! Yes, I think your thought process is on the right track. Low PTH = less VitD activation = less absorption of both Ca & Phos from the GI tract. I'm not sure if this pathophys has been studied in detail, but another thing that crosses my mind is that calcium & phos love to stick together. For example, we know that in CKD and tumor lysis syndrome, elevated phos levels lead to hypocalcemia. So in calcium alkali syndrome, the excess calcium would also drive the 3Ca + 2PO4 -> Ca3(PO4)2, thus binding up some phosphate.
Best vid on this topic i've found thx
👍👍
Great series on the topic! I have one quick question - why is the phosphate level low in this syndrome? Is it due to vitamin D being suppressed from the high Ca (so intestinal reabsorption of phosphate is minimized)? Low PTH usually means less phosphate excretion by the kidneys - so that would bring phosphate levels up - but are the intestinal loses due to low vitamin D more prominent, so that overall we have low phosphate? Thanks for any info :)
Actually, PTH causes increased excretion of phosphate in the kidneys! I like to remember this with thinking of PTH as Phosphate Trashing Hormone (got that from the Clinical Problem Solvers!)
@@decodingdx8285 Hello! Thanks for the response! Yes, that's what I thought: PTH = promotes phosphate excretion via kidneys, so a LOW PTH state (like in this syndrome) it would mean LESS phosphate excretion, right? So the low phosphate in this syndrome comes from decreased reabsorption in the GI tract due to low vitamin D, correct?
@@tszlachetka Thank you for so gently correcting me, as I misread your initial question! Yes, I think your thought process is on the right track. Low PTH = less VitD activation = less absorption of both Ca & Phos from the GI tract. I'm not sure if this pathophys has been studied in detail, but another thing that crosses my mind is that calcium & phos love to stick together. For example, we know that in CKD and tumor lysis syndrome, elevated phos levels lead to hypocalcemia. So in calcium alkali syndrome, the excess calcium would also drive the 3Ca + 2PO4 -> Ca3(PO4)2, thus binding up some phosphate.