Editing Kidney stone disease (section)

===Size===
[[File:Staghorn Kidney Stone 08779.jpg|thumb|Radiograph showing a large staghorn calculus involving the [[major calyx|major calyces]] and [[renal pelvis]] in a person with severe [[scoliosis]]]]
Stones less than {{convert|5|mm|in|1|abbr=on}} in diameter pass spontaneously in up to 98% of cases, while those measuring {{convert|5|to|10|mm|in|1|abbr=on}} in diameter pass spontaneously in less than 53% of cases.<ref name=Gettman2005 />

{{anchor|staghorn}}Stones that are large enough to fill out the renal calyces are called ''staghorn stones'' and are composed of [[struvite]] in a vast majority of cases, which forms only in the presence of [[Urease#As diagnostic test|urease-forming bacteria]]. Other forms that can possibly grow to become staghorn stones are those composed of cystine, calcium oxalate monohydrate, and uric acid.<ref name="Segura1997">{{cite journal | vauthors = Segura JW | title = Staghorn calculi | journal = The Urologic Clinics of North America | volume = 24 | issue = 1 | pages = 71–80 | date = February 1997 | pmid = 9048853 | doi = 10.1016/S0094-0143(05)70355-4 }}</ref>