Nephrolithiasis in gout: prevalence and characteristics of Brazilian patients

ABSTRACT

Abstract Background: The aims of this article were to assess the prevalence of nephrolithiasis and the factors associated with nephrolithiasis in Brazilian patients with primary gout. Methods: One hundred twenty-three patients with primary gout were recruited from a tertiary referral hospital in São Paulo, Brazil. All patients underwent ultrasonography and had their clinical and laboratory characteristics assessed. Results: One hundred fifteen (93.5%) patients were male, with a mean age of 62.9 ± 9.4 years. Twenty-three (18.7%) patients had asymptomatic nephrolithiasis (detected only by ultrasonography), 7 (6.0%) had symptomatic nephrolithiasis (detected by ultrasonography and a positive clinical history), and 13 (10.0%) had a history of kidney stones, but ultrasonography at evaluation did not show nephrolithiasis. Therefore, 35.0% of the patients had nephrolithiasis (detected either by ultrasonography and/or a positive clinical history). Nephrolithiasis was associated with male gender (43 [100%] vs 72 [90%], p = 0.049), the use of potassium citrate (13 [30.2%] vs 0, p < 0.001) and the use of medications for diabetes (10 [23.3%] vs 8 [10%], p = 0.047) and dyslipidemia (15 [34.9%] vs 10 [12.5%], p = 0.003); benzbromarone had an inverse association with nephrolithiasis (21 [48.8%] vs 55 [68.8%], p = 0.030). In patients with and without nephrolithiasis, no differences were found in the laboratory and ultrasonography characteristics, including serum uric acid levels, urinary uric acid excretion and urine pH. Conclusions: The prevalence of nephrolithiasis in primary gout was 35.0%, and 18.7% of the patients were asymptomatic. Nephrolithiasis was associated with male gender, diabetes and dyslipidemia. A positive history of nephrolithiasis probably biased the prescription of potassium citrate and benzbromarone.(AU)