The Prevalence of Simple Renal Cysts Studied by Ultrasonography, and the Relations to Age and Hypertension

Park, Jong Wook; Nam, Mee Young; Rheu, Dohyun; Koh, Young Il; Kang, Hocheol; Cho, In Jong; Lee, Seong Cheol; Choi, Ki Chul; Kang, Young Joon

Abstract

Simple renal cyst is the most common space- occupying lesion of kidney in adults. However, there were a few systematic Korean reports for the prevalence of simple renal cysts. Our purpose was to estimate the prevalence of simple renal cysts using ultrasonography, and to determine the relations to age and hypertension. The subjects were 504 volunteers (aged over 29 years) of the persons who were enrolled a health check-up program of Naju Hospital, Naju, Korea. Number of male in 504 persons was 334 (66.3%) and female 170 (33.7%). Mean age was 55 years (range; 30-86). The results were as follows: 1) One or more renal cysts were found in 50 individuals of 504 persons aged over 29 years (9.9%). In 331 persons aged over 49 years, the prevalence of simple renal cysts was 12.1%. The prevalence was significantly increased with age (P<0.001), but the difference between male (9.6%) and female (10.6%) was insignificant. 2) Mean value of cyst diameter was 23mm (5-69 mm) and was not correlated with age. However, the cyst diameter was significantly higher in female than in male, 32.4mm vs 18.0mm (P<0.001). Total number of cysts per person tended to increase with age (P<0.001). 3) The correlation between prevalence of simple renal cysts and blood pressure was statistically insignificant. However, the prevalence of hypertension in persons with cysts was higher than in persons with no cyst (27.9% vs 15.3%, P<0.05). Cyst diameter was not correlated with blood pressure. 4)Urinalysis in persons with cysts, showed microscopic hematuria in 47.4% and proteinuria in 26.3 %, however, grade of microscopic hematuria and proteinuria were not correlated with cyst diameter. The concentrations of blood urea nitrogen, serum creatinine, hemoglobin and hematocrit were not affected by presence or absence of simple renal cysts. By comparison with the recent foreign reports, the prevalence of simple renal cysts in Korean was similar to those in foreigners. Our study ascertained that simple renal cysts are age-dependent and total number of cysts per person also increases with age. In most of persons with simple renal cysts, the renal function is not affected and the related symptoms are trivial. However, we suggested that simple renal cysts may cause hypertension. To elucidate the correlation between simple renal cyst and hypertension, further studies are needed.