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Old 09-22-2011
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Default 2ary hyperparathyroidism

Can someone explain why in case of seconadry hyperpaprathyroidism the labs shows hyperphosphatemia if PTH increse due to decreased calcium (becasue of renal failure). As we know PTH is Phosphate Trashing Hormone!
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Old 09-23-2011
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Originally Posted by montre View Post
Can someone explain why in case of seconadry hyperpaprathyroidism the labs shows hyperphosphatemia if PTH increse due to decreased calcium (becasue of renal failure). As we know PTH is Phosphate Trashing Hormone!
Thanks
In secondary hyperparathyroidism, it is due to renal failure which is unable to excrete phosphate through kidney. Remember, PTH is a phosphate trashing hormone because PTH inhibits the reabsorbtion of phosphate from kidney, which happens in primary hyperparathyroidism because kidney is fine. Here, kidney is not excreting phosphate so PTH has nothing to do with it and phosphate inc in blood.

Hope it helps you.
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Old 09-23-2011
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Just to help clarify,

Kidney is not responding to to PTH, which means PTH is not being recognize by the kidney, therefore, Ca (decrease ) is not reabsorb, Phosphate (increase ) is not being excreted, but PTH (increase ) and most of the time, PTH increase, ALP goes up!

PTH by itself thinks is her problem, so it goes up! to try to compensate, and yet kidney is not responding...
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Old 09-23-2011
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Simply it is because of RF- kidney can not break down and remove phosphate. Parathyroids trash phosphate but kidneys can't get rid of it. The increased PO4 stimulaltes parathyroids & makes them overactive.
Have to remember that parathyroids respond to increased PO4 and decreased Ca. (Also pt. in ESRF are hypocalcemic as well & this stimulates PTH)
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Old 09-25-2011
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In Chronic kidney dz turned Renal failure the GFR is decreased so there is phosphate retention and decreased phosphate excretion leading to hyperphosphatemia. decreased formation of calcitrol due to renal failure leads to decreased intestinal calcium absorption,leading to hypocalcemia and PTH increases to compensate what we call sec.hyperPTism
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Old 09-25-2011
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Interesting to graps this concept good, i just got few question regarding this... silly mistakes...

Ca Decrease Po4 Increase PTH Increase and 1,25oh Decrease... in Chronic Renal Failure.
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