Editing Kidney stone disease (section)

== Risk factors ==
[[Dehydration]] from low fluid intake is a factor in stone formation.<ref name=Cutler2007 /><ref name="Curhan-1996">{{cite journal | vauthors = Curhan GC, Willett WC, Rimm EB, Spiegelman D, Stampfer MJ | title = Prospective study of beverage use and the risk of kidney stones | journal = American Journal of Epidemiology | volume = 143 | issue = 3 | pages = 240–7 | date = February 1996 | pmid = 8561157 | doi = 10.1093/oxfordjournals.aje.a008734 | doi-access = free }}</ref> Individuals living in warm climates are at higher risk due to increased fluid loss.<ref name=":0">{{cite book|title=Medical-surgical nursing : assessment and management of clinical problems| vauthors = Lewis SM |isbn=978-0-323-32852-4|oclc=944472408|year = 2017| publisher = Elsevier }}</ref> Obesity, immobility, and sedentary lifestyles are other leading risk factors.<ref name=":0" />

High dietary intake of animal [[protein]],<ref name=Cutler2007 /> [[sodium]], sugars including honey, refined [[sugar]]s, [[fructose]] and [[high fructose corn syrup]],<ref name=HFCS /> and excessive consumption of fruit juices may increase the risk of kidney stone formation due to increased [[uric acid]] excretion and elevated [[Oxalate|urinary oxalate]] levels (whereas tea, coffee, wine and beer may decrease the risk).<ref name=":0" /><ref name="Curhan-1996" />

Kidney stones can result from an underlying metabolic condition, such as [[distal renal tubular acidosis]],<ref name=Moe2006 /> [[Dent's disease]],<ref name=Thakker2000 /> [[hyperparathyroidism]],<ref name=NIDDK2006 /> primary [[hyperoxaluria]],<ref name=Hoppe2003 /> or [[medullary sponge kidney]]. 3–20% of people who form kidney stones have medullary sponge kidney.<ref name=Reilly2005Ch13 /><ref name=NIDDK20086235 />

Kidney stones are more common in people with [[Crohn's disease]];<ref name=NDDIC2006 /> Crohn's disease is associated with [[hyperoxaluria]] and malabsorption of magnesium.<ref name="pmid4416806">{{cite journal | vauthors = Farmer RG, Mir-Madjlessi SH, Kiser WS | title = Urinary excretion of oxalate, calcium, magnesium, and uric acid in inflammatory bowel disease | journal = Cleveland Clinic Quarterly | volume = 41 | issue = 3 | pages = 109–17 | year = 1974 | pmid = 4416806 | doi = 10.3949/ccjm.41.3.109 | doi-broken-date = 9 December 2024 | url = http://www.ccjm.org/content/41/3/109.short | access-date = 1 November 2013 | archive-date = 20 March 2020 | archive-url = https://web.archive.org/web/20200320210418/https://www.ccjm.org/content/41/3/109.short | url-status = live }}</ref>

A person with recurrent kidney stones may be screened for such disorders. This is typically done with a 24-hour urine collection. The urine is analyzed for features that promote stone formation.<ref name=Cavendish2008 />

=== Calcium oxalate ===
[[File:Kidney stone composed of calcium oxalate showing sharp edges.jpg|thumb|A kidney stone (yellow) composed of calcium oxalate, next to a tourmaline gemstone for scale]]Calcium is one component of the most common type of human kidney stones, [[calcium oxalate]]. Some studies suggest that people who take calcium or [[vitamin D]] as a [[dietary supplement]] have a higher risk of developing kidney stones.<ref name=IOM2010p413 /><ref name=Johri2010 />  In the [[United States]], kidney stone formation was used as an indicator of excess calcium intake by the [[Reference Daily Intake]] committee for calcium in adults.<ref name=IOM2010p8 />

In the early 1990s, a study conducted for the [[Women's Health Initiative]] in the US found that postmenopausal women who consumed&nbsp;1000&nbsp;mg of supplemental calcium and 400&nbsp;[[international unit]]s of [[vitamin D]] per day for seven years had a 17% higher risk of developing kidney stones than subjects taking a [[placebo]].<ref name=IOM2010p413 /> The [[Nurses' Health Study]] also showed an association between supplemental calcium intake and kidney stone formation.<ref name=Johri2010 />

Unlike supplemental calcium, high intakes of dietary calcium do not appear to cause kidney stones and may actually protect against their development.<ref name=Johri2010 /><ref name=IOM2010p413 /> This is perhaps related to the role of calcium in binding ingested oxalate in the gastrointestinal tract. As the amount of calcium intake decreases, the amount of oxalate available for absorption into the bloodstream increases; this oxalate is then excreted in greater amounts into the urine by the kidneys. In the urine, oxalate is a very strong promoter of calcium oxalate precipitation—about 15 times stronger than calcium.

A 2004 study found that diets low in calcium are associated with a higher overall risk for kidney stone formation.<ref name=Parmar2004 /> For most individuals, other risk factors for kidney stones, such as high intakes of dietary oxalates and low fluid intake, play a greater role than calcium intake.<ref name=Liebman2011 />

=== Other electrolytes ===
Calcium is not the only [[electrolyte]] that influences the formation of kidney stones. For example, by increasing urinary calcium excretion, high dietary sodium may increase the risk of stone formation.<ref name=Johri2010 />

Drinking [[Water fluoridation|fluoridated tap water]] may increase the risk of kidney stone formation by a similar mechanism, though further epidemiologic studies are warranted to determine whether fluoride in drinking water is associated with an increased incidence of kidney stones.<ref name=NAS2006 /> High dietary intake of [[potassium]] appears to reduce the risk of stone formation because potassium promotes the urinary excretion of [[citrate]], an inhibitor of calcium crystal formation.<ref>{{cite journal | vauthors = Ferraro PM, Mandel EI, Curhan GC, Gambaro G, Taylor EN | title = Dietary Protein and Potassium, Diet-Dependent Net Acid Load, and Risk of Incident Kidney Stones | journal = Clinical Journal of the American Society of Nephrology | volume = 11 | issue = 10 | pages = 1834–1844 | date = October 2016 | pmid = 27445166 | pmc = 5053786 | doi = 10.2215/CJN.01520216 }}</ref>

Kidney stones are more likely to develop, and to grow larger, if a person has low [[Magnesium in biology|dietary magnesium]]. Magnesium inhibits stone formation.<ref name="Riley-2013">{{cite journal | vauthors = Riley JM, Kim H, Averch TD, Kim HJ | title = Effect of magnesium on calcium and oxalate ion binding | journal = Journal of Endourology | volume = 27 | issue = 12 | pages = 1487–92 | date = December 2013 | pmid = 24127630 | pmc = 3883082 | doi = 10.1089/end.2013.0173 }}</ref>

=== Animal protein ===
[[Western pattern diet|Diets in Western nations]] typically contain a large proportion of [[protein#nutrition|animal protein]]. Eating animal protein creates an acid load that increases urinary excretion of calcium and uric acid and reduced citrate. Urinary excretion of excess sulfurous [[amino acid]]s (e.g., [[cysteine]] and [[methionine]]), uric acid, and other acidic [[metabolite]]s from animal protein acidifies the urine, which promotes the formation of kidney stones.<ref name="Negri-2013">{{cite journal | vauthors = Negri AL, Spivacow FR, Del Valle EE | title = [Diet in the treatment of renal lithiasis. Pathophysiological basis] | journal = Medicina | volume = 73 | issue = 3 | pages = 267–71 | year = 2013 | pmid = 23732207 }}</ref> Low urinary-citrate excretion is also commonly found in those with a high dietary intake of animal protein, whereas vegetarians tend to have higher levels of citrate excretion.<ref name=Johri2010 /> Low urinary citrate, too, promotes stone formation.<ref name="Negri-2013" />

=== Vitamins ===
The evidence linking [[vitamin C]] supplements with an increased rate of kidney stones is inconclusive.<ref name=Goodwin1998 /><ref>{{cite journal | vauthors = Traxer O, Pearle MS, Gattegno B, Thibault P | title = [Vitamin C and stone risk. Review of the literature] | journal = Progres en Urologie | volume = 13 | issue = 6 | pages = 1290–4 | date = December 2003 | pmid = 15000301 }}</ref> The excess dietary intake of vitamin C might increase the risk of calcium-oxalate stone formation.<ref>{{cite journal | vauthors = Ferraro PM, Curhan GC, Gambaro G, Taylor EN | title = Total, Dietary, and Supplemental Vitamin C Intake and Risk of Incident Kidney Stones | journal = American Journal of Kidney Diseases | volume = 67 | issue = 3 | pages = 400–7 | date = March 2016 | pmid = 26463139 | pmc = 4769668 | doi = 10.1053/j.ajkd.2015.09.005 }}</ref> The link between vitamin D intake and kidney stones is also tenuous.

Excessive vitamin D supplementation may increase the risk of stone formation by increasing the intestinal absorption of calcium; correction of a deficiency does not.<ref name=Johri2010 />