Kidney Stones

Abstract

There are four types of kidney stones: calcium oxalate, uric acid, phosphate, and cystine. Calcium oxalate stones are by far the most common, but proper diagnosis requires identification of the underlying disease and characterization of the type of stone. A comprehensive 24-hour urine, such as is performed by Litholink, can help guide therapy. Diet plays an important part in the control of kidney stones. With respect to calcium oxalate, it is important to consume an adequate amount of calcium and stay hydrated. Patients with recurrent oxalate stones will require potassium citrate. Uric acid stones are generally associated with diseases that cause insulin resistance. It is important to recognize that it is the urine pH that determines solubility and, that aside from hydration, potassium citrate may be needed. Xanthine oxidase inhibitors are usually not effective because the major problem is not quantity of uric acid, but whether the urine is supersaturated. Calcium phosphate crystals are associated with a high urine pH. They can be associated with distal renal tubular acidosis, medullary sponge kidneys, or primary hyperthyroidism. They can also be produced by urea splitting microorganisms. Management involves avoiding an alkaline pH and treating the underlying disease. The final cause of kidney stones is cystinosis. It is a genetic disorder that generally manifests in children and is associated with systemic deposits of cystine in body tissues. An adult form is much milder and is accompanied by corneal cystine deposits.