Editing Kidney stone disease (section)

==== Calcium-containing stones ====
By far, the most common type of kidney stones worldwide contains calcium. For example, calcium-containing stones represent about 80% of all cases in the United States; these typically contain [[calcium oxalate]] either alone or in combination with [[calcium phosphate]] in the form of [[apatite]] or [[brushite]].<ref name=Reilly2005Ch13 /><ref name=Coe2005 /> Factors that promote the [[Precipitation (chemistry)|precipitation]] of oxalate crystals in the urine, such as [[primary hyperoxaluria]], are associated with the development of calcium oxalate stones.<ref name=Hoppe2003 /> The formation of calcium phosphate stones is associated with conditions such as [[hyperparathyroidism]]<ref name=NIDDK2006 /> and [[renal tubular acidosis]].<ref name=NIDDK20084696 />

[[Oxaluria]] is increased in patients with certain gastrointestinal disorders including inflammatory bowel disease such as [[Crohn's disease]] or in patients who have undergone resection of the small bowel or small-bowel bypass procedures. Oxaluria is also increased in patients who consume increased amounts of oxalate (found in vegetables and nuts). Primary hyperoxaluria is a rare autosomal recessive condition that usually presents in childhood.<ref name="De Mais">{{cite book | vauthors = De Mais D |title= ASCP Quick Compendium of Clinical Pathology |edition= 2nd |publisher= ASCP Press |location= Chicago |year= 2009 }}</ref>

Calcium oxalate crystals can come in two varieties. Calcium oxalate monohydrate can appear as 'dumbbells' or as long ovals that resemble the individual posts in a picket fence. Calcium oxalate dihydrate have a tetragonal "envelope" appearance.<ref name="De Mais" />