Dietary factors and kidney stone formation.

Kidney stone disease is a substantial health problem associated with significant pain and suffering, as well as economic costs. Over $2 billion were spent in 1986 on stone disease, the majority on treatment of existing stones and only a small percentage on prevention. Clearly, efforts to prevent or at least reduce the likelihood of developing a kidney stone would be an important component of the care of patients at risk. In particular, modifiable dietary factors appear to play an important role in the formation of calcium oxalate stones--the type of stone formed in the vast majority of cases. Once secondary causes of stone formation, such as hyperparathyroidism and renal tubular acidosis, are excluded, dietary counselling is a prudent and effective element of the therapeutic regimen and kidney stone prevention program. Specifically, for individuals who have a history of a calcium-containing kidney stone, important dietary recommendations should include the following: Achieve adequate fluid intake to produce at least 2 liters of urine per day. Avoid calcium restriction (except in the rare instances of excessive intake of greater than several grams per day). It is recommended a dietary intake of elemental calcium of at least 800 mg/day (the current RDA for adults) to prevent a negative calcium balance, bone mineral loss, and increased intestinal absorption of oxalate. At present, there is no evidence to support the belief that calcium restriction is beneficial and current data suggest that it may in fact be harmful.(ABSTRACT TRUNCATED AT 250 WORDS)