SIMPLE RENAL CYST - RELATIONS TO AGE AND ARTERIAL BLOOD-PRESSURE

Simple renal cysts are increasingly common with increasing age, as is elevated arterial blood pressure. We studied the natural history of si mple renal cysts, and their possible association with arterial hyperte nsion. Renal sonography was performed in an age- and sex-stratified ra ndom sample of 686 healthy volunteers aged 30-70 years. Eleven examina tions were excluded for various reasons. One or more renal cysts measu ring 10-47 mm were found in 35 individuals. The prevalence of simple r enal cysts was 5.2%, ranging from 0% at age 30 to 9.7% at age 70. From the cross-sectional data it is estimated that the average renal cyst needs about 10 years to reach 20 mm in size. Mean arterial blood press ure increased with age, and was significantly higher in individuals wi th cysts (p = 0.0055). Closer analysis showed that the association was confined to and even stronger (p = 0,00066) for individuals with at l east one cyst less-than-or-equal-to 20 mm. We assume that smaller cyst s are more likely to be totally intraparenchymal, and therefore more a ble to create an internal hydrostatic pressure and thus to compress th e surrounding renal tissue.