Reduced renal function in patients with simple renal cysts

Background. Sporadic renal cysts not associated with genetic polycystic disorders are common and generally thought to be of no clinical significance. Since multiple cysts frequently develop in end-stage renal disease (ESRD), we tested the hypothesis that cysts that are solitary or few in number are an early manifestation of reduced renal function. Methods. We evaluated 561 hospitalized patients who underwent contrast-enhanced, abdominal computed tomography (CT) and correlated clinical characteristics and parameters of renal function with the presence or absence of renal cysts. Results. Age ranged from 16 to 100 years, mean serum creatinine concentration was 0.88 mg/dL (range 0.4 to 2.1 mg/dL), and mean estimated creatinine clearance was 94 mL/min/1.73 m(2) (range 22 to 218 mL/min/1.73 m(2)). The presence of cysts was significantly correlated with older age (P<0.001), higher serum creatinine concentration (P<0.002), and lower estimated creatinine clearance (P<0.001). In a multivariate analysis, including age and gender, estimated creatinine clearance still correlated with the presence of cysts (P=0.009). When patients were grouped by age, estimated creatinine clearance correlated with cysts in patients <40 years and 40 to 59 years, but not in patients 60 to 79 years or greater than or equal to80 years. There was no association of cysts with hypertension or proteinuria. In patients with cysts, serum creatinine increased progressively but not significantly with cyst number, and did not correlate with size or distribution of cysts. Renal parenchymal volume was slightly but not significantly reduced in patients with cysts. Conclusion. The presence of kidney cysts, even single cysts, is associated with reduced renal function in hospitalized patients younger than 60 years. This relationship may be obscured by the reduced renal function and the high incidence of cysts in older patients. These results suggest that acquired cystic kidney disease may begin early in the course of renal disease and that underlying renal disease should be considered in individuals with renal cysts prior to age 60 years.