Risk factors for renal cysts

OBJECTIVE To examine the risk factors for renal cysts in a large population-based health survey, as we previously reported that the prevalence of renal cyst increases with age, there is a difference in incidence between the sexes and other studies show an association between renal cysts and hypertension. SUBJECTS AND METHODS Data were collected on 17 914 individuals who participated in a multiphase health-screening programme at our institution in 2000. Ultrasonography was used for diagnosing renal cysts. Logistic analysis was used to examine various risk factors for renal cyst, including sex, age, serum creatinine, hypertension, hypercholesterolaemia, diabetes mellitus, and smoking habits. Hypertension was defined as a systolic blood pressure of > 140 mmHg, a diastolic blood pressure of > 90 mmHg, or current use of antihypertensive medication. In 45 patients with renal cysts who were followed for a mean (range) of 6 (4-7) years the sequential changes in the size of the cysts and the systolic blood pressure were plotted in relation to age. The relationship of the mean changes in these variables was also examined. RESULTS The prevalence of renal cysts was 9.9%, ranging from 3.8% for subjects in their third decade to 18.5% in their sixth. Cysts were detected in 13.0% of men and 5.8% of women (P < 0.001). The mean serum creatinine was 83 mg/L in those with cysts and 76 mg/L in those without (P < 0.001); the respective mean systolic blood pressure was 123 and 118 mmHg (P < 0.001). Multivariate logistic regression analysis showed that age (P < 0.001), sex (P < 0.001), hypertension (P = 0.0022) and serum creatinine (P = 0.021) had a significant influence on the occurrence of renal cysts. Enlargement of the cysts was not correlated with the increase in blood pressure. CONCLUSIONS The risk factors for a renal cyst are age, male gender, renal dysfunction and hypertension. Hypertension might cause renal dysfunction, which leads to the development of renal cysts.