<qa>  What is the purpose of the investigators study?The purpose of the investigators study will be to 1 characterize the urine electrolyte profile of each individual renal unit; 2 identify participants who have differences between their renal unit urine electrolyte profiles, and their renal units and bladder urine electrolyte profiles; and 3 correlate differences in renal unit urine electrolyte profiles with clinical manifestations of kidney stones, such as stone formation or growth. By characterizing individual renal unit urine electrolyte profiles, the investigators may be able to isolate a phenotype of stone formers who would not otherwise be identified with traditional 24-hour urine collection. The investigators can then target this phenotype in future investigations with dietary and medication interventions to hopefully prevent future stone events. 