Effectiveness and mode of action of orthophosphates in patients with calcareous renal calculi.

In 1958 Dr. Howard and I presented to this Associationl our initial observations indicating that urine excreted by patients with renal calculi differed in at least one respect fromi that ordinarily excreted by normal subjects. This subtle difference was demonstrated by frequent failure of urine fromi normals to nmineralize iin vitro rachitic cartilage nmatrix; whereas, urine from selected calculous patients did so with regularity, despite comparable concentrations of calcium, magnesium, and phosphorus in the tested uritne. F1'ronm these observations we deduced that urine fromi patients w-ith calcareous calculi was deficient in certain "preventers" of mineralizatioli and suggested that this deficiency might be germane to the developmeit of calculi. After additional investigation we postulated that the unidentified "preventers" or inhibitors of mineralization present in normal urine might be complex anioins that inhibit the growth of crystals in a manner analogous to that of "water-conditioners.2 " In support of this postulate, administratioIn of a polyphosphate "water-conditioner" to a few calculous patients iniduced changes in their urine, so that on incubation with rachitic cartilage the results approached those obtained with urine fronm normal subjects.2 Orthophosphate ingestion was found to cause changes in urine similar to those occurring after polyphosphates. These observations led to the concept that presentation of a phosphate load to the kidney possibly increased urinary excretion of inhibitors of crystal formation, and phosphatic salts, therefore nmiglht benefit patients with calculi. Since then we have used various ortlhoplhosphate salts in the treatment of patients with calcareous calculi.3, I To be presented in this relport are: First, the results obtained in a series of patients treated withl orthophosphates for periods of one to eight years;