TOPIC DISCUSSION

A recent quiz page in Kidney International Oct 2010 issue talks about a very interesting case of someone with hypophosphatemia and hyperphosphaturia, with normal calcium and Vitamin D levels.
A nice table shows the breakdown of someone with hypophosphetemia and loss of Phos via urine

If there is hypercalcemia along with it:- think of primary parathyroidism and post transplant parathyroid disease or pthrp production or hypocalciuric hypercalcemia.

If there is normocalcemia along with it:- only acquired disease is oncogenic osteomalacia. genetic causes are FGF23 mutation or PHEX mutation.  Usually all of them are associated with elevated FGF23 levels.
If the FGF23 are low think HHRH

If there is hypocalcemia think Barter's, Fanconi syndrome or other RTAs.

It is interesting that people are now measuring FGF23 levels to help dilenate different disorders of calcium and phosphate.  Take a look at this case in KI.

http://www.ncbi.nlm.nih.gov/pubmed/20877382