Aminoaciduria in rickets

[Phloston]

Why is there aminoaciduria in rickets?

Apparently it's not related to hyperPTH effects and is related to the calcium disturbance (i.e., it's not seen in XD familial hypophosphatemic rickets, where calcium is normal).

http://www.ncbi.nlm.nih.gov/pubmed/10584465

Anyone have insight?

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[Mleechu]

I am not sure but low vit D can cause hyper PTH > bone resorption > hydroxyproline levels go up (due to bone loss) > appears in urine?

 

[Transposony]

Nobody knows. So, it unlikely to be asked on USMLE.
However, it seems to be associated with PCT dysfunction leading to to RTA type 2 scenario.
Different studies deny a direct causative relation to PTH or Vitamin D levels since 1,25(OH)2D3 normally opposes the aminoaciduric effect of PTH.
It may be related to low levels of Carbonic anhydrase due to induction of an endogenous inhibitor protein of the cyclic AMP-dependent protein kinase exclusively in the kidney in vitamin D deficiency.

 

[Phloston]

Thanks, guys.