The most common metabolic abnormality pre¬disposing patients to renal stone formation is

The most common metabolic abnormality predispos­ing patients to renal stone formation is hypercalciuria. Calcium oxalate and calcium phosphate stones are the two most common stones. Hypercalciuria combined with decreased fluid intake is frequently associated with stone formation; thus, adequate hydration is im­portant in the treatment of stones. Hyperuricemia can contribute to stone formation, but uric acid stones are not as common as calcium stones and most people with hyperuricemia do not have stones. Distal renal tubular acidosis can lead to calcium phosphate stones, but this disorder is not as common as stone formation in hypercalciuria. In­creased urine volume and increased urine citrate con­centration would both decrease the incidence of stones. In adequate concentrations, citrate binds to calcium and renders it unavailable for stone formation.