There is currently no treatment program which is capable of correcting the basic abnormality of absorptive hypercalciuria, although several drugs are available which have been shown to restore normal calcium excretion. Sodium cellulose phosphate best meets the criteria for optimum therapy. When given orally, this non-absorbable ion exchange resin binds calcium and inhibits calcium absorption. However, this inhibition is caused by limiting the amount of intraluminal calcium available for absorption, and not by correcting the basic disturbance in calcium transport. The above mode of action accounts for the two potential complications of sodium cellulose phosphate therapy. First, the treatment may cause magnesium depletion by binding dietary magnesium as well. Second, sodium cellulose phosphate may produce secondary hyperoxaluria, by binding divalent cations in the intestinal tract, reducing divalent cation-oxalate complexation, and making more oxalate available for absorption. These complications may be overcome by oral magnesium supplementation (1.0-1.5 g magnesium gluconate twice/day, separately from sodium cellulose phosphate) and moderate dietary restriction of oxalate. Under such circumstances, sodium cellulose phosphate at a dosage of 10-15 g/d (given with meals) has been shown to lower urinary calcium, reduce urinary saturation of calcium salts and retard new stone formation, without significantly altering urinary oxalate or magnesium. When the above precautions are taken, sodium cellulose phosphate has been shown to be clinically useful in preventing new stone formation in patients with absorptive hypercalciuria.
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