Kidney Stones Research Today is a free monthly online journal that collates and summarizes the latest research about Kidney Stones, including details on causes, symptoms, treatment, diagnosis of nephrolithiasis, calculi. | ||||||||
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Rapid Communication: relative effect of urinary calcium and oxalate on saturation of calcium oxalate.Pak CY, Adams-Huet B, Poindexter JR, Pearle MS, Peterson RD, Moe OW Center for Mineral Metabolism and Clinical Research, The University of Texas Southwestern Medical Center, Dallas, Texas 75390-8571, USA. charles.pak@usouthwestern.edu BACKGROUND: The study compared the effect of urinary calcium with that of oxalate on urinary saturation [relative saturation ratio (RSR)] of calcium oxalate. METHODS: A retrospective data analysis was conducted on urinary stone risk analysis from 667 patients with predominantly calcium oxalate stones. Urinary RSR of calcium oxalate was individually calculated using Equil 2. A "theoretical" curve of the relationship between urinary RSR of calcium oxalate and concentration of calcium or oxalate was obtained at two stability constants for calcium oxalate complex, while varying calcium or oxalate and using group mean values for urinary constituents. RESULTS: At the stability constant of 7.07 x 10(3), the increase in RSR of calcium oxalate was less marked with calcium than with oxalate. However, at the stability constant of 2.746 x 10(3) from the Equil 2 that is considered the "gold standard," calcium and oxalate were equally effective in increasing RSR of calcium oxalate. The above theoretical curves (relating RSR with calcium or oxalate) were closely approximated by the actual curves constructed with data from individual urine samples. Urinary saturation of calcium oxalate was equally dependent on urinary concentrations of calcium and oxalate (r= 0.75 unadjusted and 0.57 adjusted for variables, and P < 0.0001 for calcium; r= 0.73 unadjusted and 0.60 adjusted, P <0.0001 for oxalate). CONCLUSION: Among calcium oxalate stone-formers, urinary calcium is equally effective as urinary oxalate in increasing RSR of calcium oxalate. Published 21 October 2004 in Kidney Int, 66(5): 2032-7.
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