Stone disease

Abstract

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.Background and Purpose: Ureterorenoscopy (URS) is a common minimally invasive diagnostic and therapeutic modality for ureteral and renal pathology. Fluid absorption during routine URS has not been studied prospectively, despite the fact that fluid absorption during other endoscopic urologic procedures can be substantial.Patients and Methods: During URS in 15 male and 8 female patients with a mean age of 54 years (range 19 -81 years), volumetric balance was performed by measuring all fluids instilled into the urinary tract (irrigation fluid and contrast medium) and fluids collected from the urinary tract (irrigation fluid, contrast medium, and urine output) and by estimating urine output from creatinine concentration in the urine and in the fluids collected from the urinary tract. Fluids from the urinary tract were assessed by measuring drainage fluid and the preoperative and postoperative weights of the drapes and bedsheets. Of the procedures, 11 were right-sided and 12 were leftsided. The indications for URS were urolithiasis (N = 18) and diagnosis (hematuria in 2, ureteral or renal filling defect in 2, flank pain and hydronephrosis in 1).Results: The mean total operative time was 55 minutes (range 20 -95 minutes), and the mean URS time was 37 minutes (range 8 -83 minutes). The mean volume of irrigation fluid used was 2531 mL (range 552 -5580 mL). The mean estimated urine output during the procedure was 62 mL (range 7 -201 mL). The mean estimated systemic fluid absorption during URS was 54 mL (ran...