Clinical characteristics and long-term observation of simple renal cysts in a healthy Korean population.

PURPOSE

Although simple renal cysts are common in older patients, little is known concerning their development and natural history. We investigated the characteristics of simple renal cysts and risk factors for their development in healthy Korean adults.

MATERIALS AND METHODS

The medical records of 10,261 subjects who participated in a multiphase health screening program at our institution in 2002 were reviewed. Logistic regression analysis was used to examine various risk factors for renal cyst formation including sex, age, BMI, serum creatinine, estimated GFR, proteinuria, microscopic hematuria, hypertension, hypercholesterolemia, and diabetes mellitus. In 65 patients and 79 simple renal cysts with annual follow-up for 10 years, sequential changes in size and risk factors related to cyst growth rate were analyzed.

RESULTS

The prevalence of simple renal cysts was 5.43 %. Age (p < 0.001), BMI (p < 0.001), proteinuria (p = 0.011), microscopic hematuria (p < 0.001), estimated GFR (p < 0.001), and hypertension (p < 0.001) had a significant influence on the occurrence of simple renal cysts. The average growth rates of simple renal cysts over the 10-year follow-up period were 1.43 mm (6.5 %) per year. Age <50 years was the only significant predictor of growth rates of renal cysts in the multivariate analysis (β = 2.37; 95 % CI 0.52, 4.22; p = 0.013).

CONCLUSION

Age, BMI, renal dysfunction, proteinuria, microscopic hematuria, and hypertension were found to be risk factors for the presence of simple renal cysts. Simple renal cysts in younger patients (<50 years) tend to have a more rapid increase in size, but generally do not progress to aggressive disease.