Urinary citrate and stone disease

Citrate plays an important role in calcium oxalate stone formation. Hypocitraturia has now been found in topiramate therapy, bariatric surgery, and high-protein low-carbohydrate diet. Citrate indirectly reduces urinary saturation of stone-forming calcium salts by complexing calcium and reducing ionized calcium fraction in urine; its direct effect on nucleation, crystal growth, and agglomeration is minor or uncertain. Hypocitraturia can be readily corrected by potassium citrate treatment. This treatment also increases urinary pH. The physicochemical effects of increased urinary citrate and pH from potassium citrate treatment when critically examined by estimating urinary saturation of brushite and calcium oxalate reveal that potassium citrate treatment does not increase urinary saturation of brushite and more dramatically decreases the saturation of calcium oxalate.