Kidney and increased PTH question...

[CatsandCradles]

Hi guys, I have a kidney question.

I was wondering about this, suppose that there is a tumor causing the parathyroid gland to go crazy and give off tons and tons of PTH.

I know that PTH will increase plasma phosphate, inhibit phosphate reabsorption and phosphate ecxretion.

And I also know that the kidneys will excrete H+ bound to phosphate as H2PO4....And I know that the kidneys also needs to secrete H+ to reform and recover HCO3.

So if there's a ton of PTH causing there to be an abnormally high amount of phosphate to be filtered...

What will this do to the patient's pH? I can't seem to put things together here. I know that HC03 is important when your pH drops below normal. So if the H+ that the kidney is secreting is being taken up more than normal because of all the phosphate...does this mean the person's pH is going to drop through the floor? Or will it not affect pH cause the H will also be excreted from the kidneys as H2P04?

Sorry for all the confusion and
Thanks a million!

C&C

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[Bill_252001]

PTH is associated with calcium regulation, never heard Phosphate being regulated by PTH, although I am not yet a med student.

 

[beastmaster]

PTH is associated with calcium regulation, never heard Phosphate being regulated by PTH, although I am not yet a med student.

hahahahahahaaha.... Ok, in exchange for the good laugh I just had, I'll answer the question.

Hyperparathyroidism, by excreting more phosphate and bicarb proximally, would produce a hypokalemic (exchanged for H+) hyperchloremic (exchanged for bicarb) mild metabolic acidosis with a high urine pH. It's called renal tubular acidosis.

 

[sistermike]

PTH is associated with calcium regulation, never heard Phosphate being regulated by PTH, although I am not yet a med student.

You weren't totally off -- I assume you learned this in an undergrad bio class. I, too, am an undergrad student and took my two semesters of A&P and although we learned what the poster said below me... PTH (Parathyroid Hormone) does work to increase blood calcium. Aside from the calcium though, PTH also targets the intestines, kidneys, and of course the bones.

 

[Droopy Snoopy]

Hi guys, I have a kidney question.
I was wondering about this, suppose that there is a tumor causing the parathyroid gland to go crazy and give off tons and tons of PTH.
I know that PTH will increase plasma phosphate, inhibit phosphate reabsorption and phosphate ecxretion.
And I also know that the kidneys will excrete H+ bound to phosphate as H2PO4....And I know that the kidneys also needs to secrete H+ to reform and recover HCO3.
So if there's a ton of PTH causing there to be an abnormally high amount of phosphate to be filtered...
What will this do to the patient's pH? I can't seem to put things together here. I know that HC03 is important when your pH drops below normal. So if the H+ that the kidney is secreting is being taken up more than normal because of all the phosphate...does this mean the person's pH is going to drop through the floor? Or will it not affect pH cause the H will also be excreted from the kidneys as H2P04?
Sorry for all the confusion and
Thanks a million!
C&C

By decreasing bicarbonate reabsorption you decrease pH, important because acidification of plasma causes a conformation change in Ca-binding proteins causing them to release Ca (one of the many ways PTH increases plasma Ca). It's not drastic however. You're not going to go around treating alkalotic patients with PTH, or have someone overnight develop massive parathyroid tumors that make pH "drop through the floor"; rather compensatory mechanisms will gradually come into effect.

 

[likhary]

you right, but What will this do to the patient's pH? I can't seem to put things together here. I know that HC03 is important when your pH drops below normal. So if the H+ that the kidney is secreting is being taken up more than normal because of all the phosphate...does this mean the person's pH is going to drop through the floor? Or will it not affect pH cause the H will also be excreted from the kidneys as H2P04?