It was once thought dietary calcium was a major cause of kidney stones. This studies the formation of kidney stones, from their initial formation as tiny crystals, in solution.

Urinary tract factors, kidney disorders such as cystic kidney diseases, and metabolic disorders such as hyperparathyroidism, all linked to stone formation. Certain intestinal disorders can increase the risk, as can taking medications , like protease inhibitors. Urine can dissolve no more than 300mg of cystine in a liter, and normal people lose less than 100mg daily in their urine. Cystine is present in blood and filtered from blood by the kidney in very large amounts. Urine leaves the bladder and goes out of the body through a tube called the urethra.

Urine is mostly made up of water, but if a person doesn't drink enough water there might not be enough urine to dilute the minerals building up in the kidneys. Urologists (doctors who specialize in treating kidney disease) recommend drinking at least eight glasses of water every day. Urine usually contains chemicals that prevent stones from forming, but sometimes these do not work and the stones appear. If the stones are tiny enough, they will travel through the body with urine and pass undetected. Urinary tract infections, kidney disorders and metabolic disorders such as hyperparathyroidism can lead to stone formation. Also, people with rare hereditary diseases, including renal tubular acidosis, cystinuria and hyperoxaluria, can develop kidney stones.

Cystinuria and hyperoxaluria are two other rare, inherited metabolic disorders that often cause kidney stones. In cystinuria, too much of the amino acid cystine, which does not dissolve in urine, is voided. Cystine stones are rare. Cystine stones arise in both men and women similarly.

Cystine stones form when there is a high level of cystine in your urine, which is caused by a hereditry disorder called cystinuria. This last type of stone is rare and only consists of 1 out of 100 of all kidney stones. Cystine stones tend to develop earlier in life than other kidney stones, usually between the ages of 10 and 30 years. Cystinuria is an inherited condition and uncommon. Some rare stones are silicate struvite stones and xanthine.