Editing Calcium oxalate (section)

==Medical significance==
Calcium oxalate can produce sores and numbing on ingestion and may even be fatal.

===Morphology and diagnosis===
The monohydrate and dihydrate can be distinguished by the shape of the respective crystals. 
* Calcium oxalate ''dihydrate'' crystals are [[Octahedral molecular geometry|octahedral]]. A large portion of the crystals in a urine sediment will have this type of morphology, as they can grow at any pH and naturally occur in normal urine.
* Calcium oxalate ''monohydrate'' crystals vary in shape, and can be shaped like dumbbells, spindles, ovals, or picket fences, the last of which is most commonly seen due to [[ethylene glycol poisoning]].<ref>{{cite web|title=Urine Crystals|url=https://ahdc.vet.cornell.edu/clinpath/modules/UA-ROUT/crystsed.htm|website=ahdc.vet.cornell.edu/|publisher=Cornell University|access-date=12 July 2014}}</ref>
<gallery>
File:Calcium oxalate crystals in urine.jpg|Urine microscopy showing calcium oxalate crystals in the urine. The [[Octahedron|octahedral]] crystal morphology is clearly visible.
File:Calcium oxalate crystals (urine) - kalsiyum oksalat kristalleri (idrar) - 01.png|Urine microscopy showing a ''calcium oxalate monohydrate'' crystal (dumbbell shaped) and a ''calcium oxalate dihydrate'' crystal (envelope shaped) along with several erythrocytes.
File:Calcium oxalate crystals (urine) - kalsiyum oksalat kristalleri (idrar) - 02.png|Urine microscopy showing several ''calcium oxalate monohydrate'' crystals (dumbbell shaped, some of them clumped) and a ''calcium oxalate dihydrate'' crystal (envelope shaped) along with several erythrocytes.
File:Calcium Oxalate Detail.png|Urinary sediment showing several calcium oxalate crystals. 40X
File:Urine crystals comparison.png|Comparison of different types of urinary stones.
File:Histopathology of a breast cyst with calcium oxalate crystals, annotated.jpg|Histopathology of calcium oxalate crystals in a benign breast cyst, H&E stain. In the breast, they can be seen on [[mammography]] and are usually benign, but can be associated with [[lobular carcinoma in situ]].<ref>Image by Mikael Häggström, MD.<br>- Reference for benign/LCIS association: {{cite web|url=https://www.pathologyoutlines.com/topic/breastcalcification.html|title=Microcalcifications|author=Hind Warzecha, M.D.|website=Pathology Outlines}} Last author update: 1 June 2010</ref>
</gallery>

===Kidney stones===
{{multiple image
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 | footer = Calcium oxalate monohydrate stones can be spiculated, resembling the head of a [[Morning star (weapon)|morning star]].
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{{Main|Kidney stone disease#Diagnosis}}
About 76% of kidney stones are partially or entirely of the calcium oxalate type.<ref name="Singh"/> They form when urine is persistently saturated with calcium and oxalate. Between 1% and 15% of people globally are affected by kidney stones at some point.<ref name=BMJ2016>{{cite journal|last1=Morgan|first1=Monica S C|last2=Pearle|first2=Margaret S|title=Medical management of renal stones|journal=BMJ|year=2016|volume=352|pages=i52|issn=1756-1833|doi=10.1136/bmj.i52|pmid=26977089|s2cid=28313474}}</ref><ref name=":3">{{Cite journal|date=6 September 2020|title=Prevalence and Trends in Kidney Stone Among Adults in the USA: Analyses of National Health and Nutrition Examination Survey 2007–2018 Data|url=https://www.sciencedirect.com/science/article/abs/pii/S2405456920302248|journal=European Urology Focus|language=en|doi=10.1016/j.euf.2020.08.011|issn=2405-4569|last1=Abufaraj|first1=Mohammad|last2=Xu|first2=Tianlin|last3=Cao|first3=Chao|last4=Waldhoer|first4=Thomas|last5=Seitz|first5=Christian|last6=d'Andrea|first6=David|last7=Siyam|first7=Abdelmuez|last8=Tarawneh|first8=Rand|last9=Fajkovic|first9=Harun|last10=Schernhammer|first10=Eva|last11=Yang|first11=Lin|last12=Shariat|first12=Shahrokh F.|volume=7 |issue=6 |pages=1468–1475 |pmid=32900675|s2cid=221572651|doi-access=free|url-access=subscription}}</ref> In 2015, they caused about 16,000 deaths worldwide.<ref name=GBD2015De>{{cite journal | vauthors = Vos T, Allen C, Arora M, Barber RM, Bhutta ZA, Brown A, etal | collaboration = GBD 2015 Disease and Injury Incidence and Prevalence Collaborators | title = Global, regional, and national life expectancy, all-cause mortality, and cause-specific mortality for 249 causes of death, 1980–2015: a systematic analysis for the Global Burden of Disease Study 2015 | journal = Lancet | volume = 388 | issue = 10053 | pages = 1459–1544 | date = October 2016 | pmid = 27733281 | pmc = 5388903 | doi = 10.1016/s0140-6736(16)31012-1}}</ref>

Some of the oxalate in urine is produced by the body. Calcium and oxalate in the diet play a part but are not the only factors that affect the formation of calcium oxalate stones. Dietary oxalate is an organic ion found in many vegetables, fruits, and nuts. Calcium from bone may also play a role in kidney stone formation.