Phosphate treatment of recurrent calcium stone disease.

A group of 38 male recurrent idiopathic calcium stone formers were treated with oral supplements of orthophosphate (1 g phosphorus extra in the diet per day) and followed at intervals up to 4 years. The urinary excretion of calcium decreased (p less than 0.001) and that of inorganic phosphate increased (p less than 0.001) during treatment. These changes resulted in a small decrease in the supersaturation of urine with respect to calcium oxalate, sufficient to reduce the percentage of urines which exceeded the upper limit of solubility of that salt, and a small increase in the supersaturation of urine with respect to calcium phosphate. The stone episode rate on treatment fell in 35 of the 38 patients from a mean pretreatment value of 0.66 episodes/year to 0.22 episodes/year. The 3 initially most prolific stone formers increased their rate of stone formation during treatment. Plasma biochemistry showed no evidence of parathyroid stimulation.