Nephrolithiasis among male patients with newly diagnosed gout

Introduction: An elevated serum urate level is recognised as a cause of gouty arthritis and uric acid stone. The level of serum uric acid that accelerates kidney stone formation, however, has not yet been clarified. This study aimed to find out if a high serum urate level is associated with nephrolithiasis. Methods: Patients were recruited from the rheumatology clinic of Taipei City Hospital (Renai and Zhongxing branches) in Taiwan from March 2015 to February 2016. A total of 120 Chinese male patients with newly diagnosed gout and serum urate concentration of >7 mg/dL and no history of kidney stones were divided into two groups according to their serum urate level: <10 mg/dL (group 1, n=80) and >= 10 mg/dL (group 2, n=40). The mean body mass index, blood urea nitrogen level, creatinine level, urinary pH, and kidney ultrasonography were compared between the two groups. Results: There were no significant differences in blood urea nitrogen or creatinine level between the two groups. The urine pH in both groups was similar and not statistically significant. Kidney stone formation was detected via ultrasonography in 6.3% (5/80) and 82.5% (33/40) of patients in groups 1 and 2, respectively (P<0.05). Conclusion: A serum urate level of >= 10 mg/dL may precipitate nephrolithiasis. Further studies are warranted to substantiate the relationship between serum urate level and kidney stone formation.