Editing Stones: Epidemiology and Pathogenesis (section)

== Other stones ==

=== Matrix stones ===
* Rare
* '''Predominately composed (65%) of organic proteins''', sugars, and glucosaminses, unlike other stones that have minimal organic material (2.5%)
** Among the proteins incorporated into the matrix substance are Tamm-Horsfall protein, nephrocalcin, a γ-carboxyglutamic acid–rich protein, renal lithostathine, albumin, glycosaminoglycans, free carbohydrates, and a mucoprotein called matrix substance A
* '''Risk factors (4)'''
*#'''Recurrent UTI by urea-splitting bacteria'''
*#'''Previous stone formation'''
*#'''Previous surgery due to urolithiasis'''
*#'''Obstructive uropathy'''
* '''Diagnosis and Evaluation'''
**'''Imaging'''
***'''Challenging to diagnose preoperatively, as they can mimic upper tract collecting system soft-tissue masses''' and require a high index of suspicion
*** '''Radiolucent on plain film x-ray'''

=== Xanthine stones ===
* '''Result of an inherited disorder in xanthine dehydrogenase (XDH)''' or xanthine oxidase.
* '''Allopurinol, which inhibits XDH''' and is consequently used to treat hyperuricemia and hyperuricosuria, '''can, at high levels, predispose to xanthine stones'''. This side effect is distinctly uncommon
* '''Radiolucent on plain film x-ray'''

=== 2,8-dihydroxyadenine stone ===
* Results from adenine phosphoribosyltransferase deficiency, a rare autosomal recessive disorder
* '''Radiolucent on plain film x-ray'''

=== Ammonium acid urate stones ===
* Infrequently seen in industrialized nations
* '''Associated with laxative abuse, recurrent UTI, recurrent uric acid stone formation, inflammatory bowel disease, and children with low-protein, low-phosphate diet resulting in primary bladder calculus'''
** '''Ammonium excretion is increased with starvation, dehydration, or consumption of acid-forming foods or toxins§'''
** Subjects who abuse laxatives are chronically dehydrated, resulting in intracellular acidosis. In addition, urinary sodium is low from sodium loss as a result of the laxatives. In this environment, urate preferentially complexes with the abundant ammonium rather than sodium and produces ammonium acid urate stones.

=== Medication associated stones[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1508366] ===
*'''<span style="color:#0000ff">Lotta Good Drugs Cause Calculi FIT TEST (12):''' 
*# '''<span style="color:#0000ff">L<span style="color:#ff0000">axatives'''
*# '''<span style="color:#0000ff">G<span style="color:#ff0000">uaifenesin'''
*# '''<span style="color:#ff0000">Vitamin <span style="color:#0000ff">D'''
*# '''<span style="color:#ff0000">Vitamin <span style="color:#0000ff">C</span>''' in high doses is converted to oxalate and may induce hyperoxaluria
*# '''<span style="color:#0000ff">C<span style="color:#ff0000">arbonic anhydrase inhibitors'''
*#*E.g. acetazolamide
*#*May be associated with the formation of calcium-based calculi, '''particularly calcium phosphate'''
*# '''<span style="color:#0000ff">F<span style="color:#ff0000">urosemide'''
*#* '''Thiazides''' cause intracellular acidosis and '''subsequent hypocitraturia'''
*# '''<span style="color:#0000ff">I<span style="color:#ff0000">ndinavir'''
*#* '''MOA: protease inhibitor'''
*#* '''Used in patients with HIV/AIDS.'''
*#* Individuals taking indinavir on a regular basis are at high risk of producing indinavir stones because of the high urinary excretion and poor solubility of the drug at physiologic urinary pH.
*#* '''Now infrequently used''', replaced with newer generation agents. Kidney stone formation has been associated with a number of newer anti-retroviral agents.
*#* '''Radiolucent on plain film and may not be seen on CT'''
*# '''<span style="color:#0000ff">T<span style="color:#ff0000">opiramate'''
*#* '''MOA: carbonic anhydrase inhibitor'''
*#*Used to treat epilepsy and prevent migraines
*#* Creates a chronic intracellular acidosis resulting '''in a urinary milieu similar to distal RTA''' with hyperchloremic acidosis, high urine pH, extremely low urinary citrate, and hypercalciuria.
*#* '''Treatment may be potassium citrate''' or cessation of the medication if possible.
*# '''<span style="color:#0000ff">T<span style="color:#ff0000">riamterene'''
*#* '''MOA: potassium-sparing diuretic'''
*#* Used for the treatment of hypertension
*#* '''Radiolucent'''
*# '''<span style="color:#0000ff">E<span style="color:#ff0000">phedrine'''
*# '''<span style="color:#0000ff">S<span style="color:#ff0000">ilicates'''
*# '''<span style="color:#0000ff">T<span style="color:#ff0000">MP/SMX'''