The effect of crystalline monosodium urate on the crystallisation of calcium oxalate in whole human urine.

Samples of undiluted urine from normal men were preincubated with crystalline monosodium urate and their metastable limits and responses to a standard oxalate challenge were compared with results obtained from control samples preincubated without urate. Preincubation with urate had no significant effect on the metastable limits of the urines, the morphology, size, or growth rates of calcium oxalate crystals precipitated from the urines, or on the total amount of calcium oxalate deposited in a given time. It was concluded that particulate monosodium urate is unlikely to influence calcium oxalate stone formation by binding to and attenuating the potency of urinary inhibitors.