Comparison of Clinico-Metabolic Characteristics between Calcium Oxalate and Uric Acid Stone Formers

Abstract

Purpose: Although both intrinsic and environmental factors contribute to urinary stone formation, recent epidemiologic studies have suggested the importance of lifestyle and dietary habit in urolithiasis. The aim of this study was to compare clinical and metabolic characteristics between calcium oxalate (CaOx) and uric acid (UA) stone formers (SF). Materials and Methods: A database of patient histories and serum and urine chemistries was analyzed for 172 consecutive stone formers [124 pure CaOx SF, 25 mixed (CaOx-UA) SF, and 23 pure UA SF]. We compared the clinical profiles and urinary metabolites among these groups. Urinary CaOx supersaturation was assessed by using the Okawa index. Results: Compared with pure CaOx SF, SF with an increased UA component were older (p=0.01) and had a higher body mass index (BMI) (p=0.02). However, there were no significant differences in gender, stone episodes, family history, or serum chemistry among the three groups (p> 0.05). In the SF with a greater calcium component, urinary excretion of calcium and CaOx supersaturation were significantly elevated (p<0.01, respectively). On the contrary, SF with an increased UA component had significantly decreased urine pH (p=0.03). Conclusions: This study revealed that CaOx stone formation was associated with a young age, hypercalciuria, and high CaOx supersaturation, whereas UA stone formation was associated with high BMI and low urine pH. This study suggests that modification of risk factors in urolithiasis may contribute to preventing stone formation and stone recurrence. (Korean J Urol 2009;50:897-901) 󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏