STONE DISEASE _______________________________________________________________ Obesity, weight gain, and the risk of kidney stones

JAMA. 2005; 293: 455-62 Context: Larger body size may result in increased urinary excretion of calcium, oxalate, and uric acid, thereby increasing the risk for calcium-containing kidney stones. It is unclear if obesity increases the risk of stone formation, and it is not known if weight gain influences risk. Objective: To determine if weight, weight gain, body mass index (BMI), and waist circumference are associated with kidney stone formation. Design, Setting, and Participants: A prospective study of 3 large cohorts: the Health Professionals Follow-up Study (N = 45,988 men; age range at baseline, 40-75 years), the Nurses’ Health Study I (N = 93,758 older women; age range at baseline, 34-59 years), and the Nurses’ Health Study II (N = 101,877 younger women; age range at baseline, 27-44 years). Main Outcome Measures: Incidence of symptomatic kidney stones. Results: We documented 4827 incident kidney stones over a combined 46 years of follow-up. After adjusting for age, dietary factors, fluid intake, and thiazide use, the relative risk (RR) for stone formation in men weighing more than 220 lb (100.0 kg) vs men less than 150 lb (68.2 kg) was 1.44 (95% confidence interval [CI], 1.11-1.86; P = .002 for trend). In older and younger women, RRs for these weight categories were 1.89 (95% CI, 1.52-2.36; P<.001 for trend) and 1.92 (95% CI, 1.59-2.31; P<.001 2005; 173: 467-73 Purpose: We studied the role of open surgery versus percutaneous nephrolithotomy (PCNL) in the treatment of complete staghorn stones in a prospective randomized manner. Materials and Methods: A total of 79 patients with 88 complete staghorn stones, defined as filling the collecting system 80% were prospectively randomized for PCNL (43) or open surgery (45). Intraoperative and postoperative morbidity, operative time, stay, and stone clearance at and followup were for both methods. Patients with significant residuals in both groups were subjected to extracorporeal shock wave lithotripsy (Dornier Medical on an outpatient basis. Followup was completed for all cases with a mean duration +/- SD of 4.9 +/- 2.5 months (range 3 to 14). Renal function was evaluated by Tc-mercaptoacetyltriglycine renogram before and after treatment in both groups.Results: