[lemontea88]

I faced a question on this on USMLE Rx. Their answer is Calcium, which I totally disagree on because I though its an Ammonium Magnesium Phosphate stone?

I tried googling but couldn't really get anything.

What do you guys think?

 

[DrSeddik]

I think you are correct. But first, staghorn is a morphological rather than a chemical discription, as cystine stones may also cause staghorn calculi, but much less frequently.

Also struvite stones contain variable amounts of calcium beside ammonium, phosphate and magnesium, so it depends on the choices you have, but generally, saying calcium stones means either calcium phosphate or calcium oxalate

 

[khanar]

staghorn calculus means a stone that is found in the pelvis and extends to one or more calyces

It can be any type of renal stones but most commonly a struvite stone.
That question in USMLERx if it said that calcium is more common than struvite then it's 100% wrong.