Prevalence and clinical characteristics of simple renal cyst.

BACKGROUND We investigated simple renal cysts to understand the prevalence in healthy individuals and evaluate their clinical characteristics to determine whether or not there are any risk factors associated with simple renal cysts. METHODS Abdominal sonography was performed in 577 individuals (317 men, 260 women; mean age, 48.84 years; age range, 20-94 years) who received health check-up in January to February 2005. Data including age, sex, renal sonographic findings (cyst number, site, diameter, renal stones), values of serum cholesterol, glucose and creatinine, urine analysis (proteinuria, hematuria, pyuria), and smoking habit were analyzed. RESULTS The overall prevalence of simple renal cysts was 10.7%, ranging from 2.38% in the 2nd to 35.29% in the 7th or later decade of life. The prevalence increased with age (p<0.001). The mean age of individuals with cysts was significantly older than those without cysts (57.65+/-13.35 vs. 47.78+/-12.40 years; p<0.001). Male-to-female ratio was 2.81 (15.14% vs. 5.38%; p<0.001). The majority of cysts were solitary (82.3%). Mean largest diameter of cysts was 20.89+/-12.62 mm. The mean size of cysts in every age group was not statistically different. Factors significantly associated with simple renal cysts were age (odds ratio [OR], 4.37; p<0.001), sex (OR, 0.32; p<0.001), serum creatinine (OR, 11.77; p=0.001), proteinuria (OR, 3.11; p=0.004), renal stone (OR, 2.47; p=0.006), and smoking (OR, 2.80; p<0.001). However, in multivariate analysis, except proteinuria, all of the above factors were significantly related to the occurrence of simple renal cysts. CONCLUSION The overall prevalence of simple renal cysts in healthy individuals was 10.7%. Age, sex, renal stone, serum creatinine, and smoking were found to be risk factors for the presence of simple renal cysts.