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Kidney Stones

Update in Diagnosis and Management

Hyperuricosuria is a Risk Factor for Calcium Oxalate Stones

Slide 22

February 2010

Increased urinary uric acid excretion has also been identified as a risk factor for calcium oxalate stones. The mechanism is not entirely clear, and at least 3 hypotheses have been put forth. Increased urinary uric acid may serve to salt out calcium oxalate, which is already almost always supersaturated in the urine. Uric acid crystals could also serve as heterogeneous nucleation sites for calcium oxalate. Finally, uric acid and/or uric acid crystals could bind and inactivate urinary macromolecular inhibitors. Varying degrees of evidence exist for each of these possibilities. Treatment for this subgroup of patients includes allopurinol, which blocks uric acid production, as well as potassium citrate, which presumably acts to block uric acid precipitation in the urine.

Risk Factor


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