PHYSIOLOGICAL-EFFECTS OF SLOW-RELEASE POTASSIUM PHOSPHATE FOR ABSORPTIVE HYPERCALCIURIA - A RANDOMIZED DOUBLE-BLIND TRIAL

Purpose: We examined the physiological effects and tolerance of UroPho s-K,parallel to a slow release neutral form of potassium phosphate (15 5 mg. phosphate and 8 mEq. potassium per tablet) in patients with abso rptive hypercalciuria. Materials and Methods: A total of 31 patients w ith absorptive hypercalciuria were studied at baseline and after 3 mon ths of treatment with 4 tablets twice daily of UroPhos-K or placebo (i dentical in appearance) in a prospective randomized, placebo controlle d, double-blind trial during a 4-day inpatient study with a daily cons tant metabolic diet containing 400 mg. calcium, 100 mEq. sodium and 80 0 mg. phosphate. Results: Treatment with UroPhos-K did not cause signi ficant gastrointestinal side effects, increase fasting serum potassium or phosphorus, or reduce hemoglobin or creatinine clearance. It reduc ed urinary calcium excretion from 277 +/- 72 to 166 +/- 43 mg. per day (p <0.001), associated with a reduction in serum 1,25-dihydroxyvitami n D concentration from 50 +/- 11 to 42 +/- 9 pg./ml. (p <0.001). Index es of intestinal calcium absorption and markers of bone turnover also decreased modestly. None of these changes was seen in the placebo grou p. Conclusions: In patients with absorptive hypercalciuria UroPhos-K s eems to correct hypercalciuria by a combination of reduced intestinal absorption, bone resorption and improved renal calcium reabsorption. T he drug is well tolerated compared to placebo.