Step II Primary Hypophosphatemia

[cheruka]

primary hypophosphatemia, lab results will show decreased serum calcium, low serum phosphate, elevated (not decreased) alkaline phosphatase, as well as increased PTH.
Can someone tell me why would there be low calcium with hypophosphatemia?
Thanks!

 

[Leonid Rogozov]

This might be wrong (not a med student) but here it goes: Doesn't it have something to do with the osteoclasts not sending calcium and phosphates into the blood (instead osteoblasts sends alkaline phosphatase) while the body tries to compensate by releasing PTH?

Studying for histology right now. Wanted to see if I'm synthesizing info well. ^^

 

[EM4Reals]

Thats wrong. Primary hypophosphatemia causes high phosphate levels (not low) with low calcium. Vitamin D deficiency would cause hypocalcemia with hypophosphatemia. I dont know where you're getting your info from.

 

[Leonid Rogozov]

Thats wrong. Primary hypophosphatemia causes high phosphate levels (not low) with low calcium. Vitamin D deficiency would cause hypocalcemia with hypophosphatemia. I dont know where you're getting your info from.

Umm...

http://en.wikipedia.org/wiki/Hypophosphatemia

It may be wiki but I think they get their 'hypos' and 'hypers' right.

 

[EM4Reals]

Ahhh.....I miss read your post. I thought you were talking about hypoparathyroidism! My bad! (I even copied hypophosphatemia...doh)

 

[EM4Reals]

So my guess for you actual question is that hyperphosphatemia is a trigger for release of PTH, so my guess is that during hypophosphatemia PTH levels are low? causing low calcium? Thats my best guess!

 

[Leonid Rogozov]

Ahhh.....I miss read your post. I thought you were talking about hypoparathyroidism! My bad! (I even copied hypophosphatemia...doh)

No worries. 👍

 

[Leonid Rogozov]

So my guess for you actual question is that hyperphosphatemia is a trigger for release of PTH, so my guess is that during hypophosphatemia PTH levels are low? causing low calcium? Thats my best guess!

I'm thinking hereditary rickets?

 

[EM4Reals]

Yeah that seems like the most reasonable cause.

 

[cheruka]

So, do you expect to see any difference between lab values caused by x-linked hypophosphatemia (primary) vs. hypophosphatemia caused by refeeding syndrome? It seems to me that both should have low phosphate but normal calcium and PTH.

 

[Leonid Rogozov]

So, do you expect to see any difference between lab values caused by x-linked hypophosphatemia (primary) vs. hypophosphatemia caused by refeeding syndrome? It seems to me that both should have low phosphate but normal calcium and PTH.

K+ and Mg+ levels should be falling in refeeding syndrome whereas they aren't affected by x-linked hypophosphatemia.