Index Calcium-containing stonesStruvite stonesUric acid stonesOther typesDepending on locationCalcium-containing stonesThe most common type of kidney stones in the world contains calcium. They typically contain calcium oxalate alone or in combination with calcium phosphate in the form of apatite or brushite. Factors that promote precipitation of oxalate crystals in the urine, such as primary hyperoxaluria, are associated with the development of calcium oxalate stones. Calcium phosphate stone formation is associated with conditions such as hyperparathyroidism and renal tubular acidosis. Oxaluria is increased in patients with certain gastrointestinal disorders, including inflammatory bowel disease such as Crohn's disease, or in patients who have undergone small bowel resection or small bowel bypass procedures. Oxaluria also increases in patients who consume high amounts of oxalate (found in vegetables and nuts). Primary hyperoxaluria is a rare autosomal recessive condition that usually occurs in childhood. Calcium oxalate stones appear microscopically as "envelopes." They can also form "dumbbells". Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an Original Essay Struvite Stones Approximately 10–15% of urinary stones are composed of struvite (magnesium ammonium phosphate, NH4MgPO4•6H2O). Struvite stones (also known as “infectious stones,” urease or triple phosphate stones) most often form in the presence of infection by bacteria that break down urea. Using the enzyme urease, these organisms metabolize urea into ammonia and carbon dioxide. This alkalizes the urine, creating favorable conditions for the formation of struvite stones. Proteus mirabilis, Proteus vulgaris and Morganella morganii are the most common organisms isolated; Less common organisms include Ureaplasma urealyticum and some species of Providencia, Klebsiella, Serratia, and Enterobacter. These infectious stones are commonly seen in individuals who have factors that predispose them to urinary tract infections, such as those with spinal cord injury and other forms of neurogenic bladder, ileal conduit urinary diversion, vesicoureteral reflux, and obstructive uropathies. They are also commonly seen in people with underlying metabolic disorders, such as idiopathic hypercalciuria, hyperparathyroidism, and gout. Infectious stones can grow rapidly, forming large antler-shaped (horn-shaped) calyceal stones that require invasive surgery such as percutaneous nephrolithotomy for definitive treatment. Struvite stones (triple phosphate/magnesium ammonium phosphate) have a “coffin lid” morphology under the microscope. Uric acid stones Approximately 5-10% of all stones are made up of uric acid. People with certain metabolic abnormalities, including obesity, can produce uric acid stones. They may also form in association with conditions that cause hyperuricosuria (an excessive amount of uric acid in the urine) with or without hyperuricemia (an excessive amount of uric acid in the serum). They can also form in association with acid/base metabolism disorders in which the urine is excessively acidic (low pH), resulting in the precipitation of uric acid crystals. A diagnosis of uric acid urolithiasis is supported by the presence of a radiolucent stone in the face of persistent acidity of the urine, in conjunction with the finding of uric acid crystals in fresh urine samples. As noted above (section on calcium oxalate stones), patients with inflammatory bowel disease (Crohn's disease, ulcerative colitis) tend to have hyperoxaluria and form stones.