Prevalence of renal cysts in a Middle-Eastern population: an evaluation of characteristics and risk factors.

Objective: To assess the prevalence of renal cysts in a large Middle-Eastern population presenting for a health-screening programme, evaluating cyst characteristics and risk factors for their development.

Patients And Methods: The reported prevalence of renal cysts detected by ultrasonography (US) in the general population is 5.0-20.8%, and their development has been linked to several factors. The electronic charts of 8551 patients (from eight nations, predominantly Egypt and Yemen) presenting for the 'check-up' programme at the author's institution during 2005 were retrospectively reviewed. The presence and characteristics of renal cysts on abdominal US were noted, as were any associated renal pathologies. Various risk factors were evaluated for renal cyst development, i.e. age, gender, hypertension, diabetes mellitus and serum creatinine levels, and hyperlipidaemia and a history of bilharziasis were also assessed.

Results: The prevalence of renal cysts was 4.2%, ranging from 0.6% for patients in their third decade, to a third of those aged >80 years. Cysts were detected in 4.8% of men and 2.8% of women (P < 0.001). The mean serum creatinine level was 1.02 mg/dL in those with cysts and 0.88 mg/dL in those without (P < 0.001). On univariate analysis, hypertension, diabetes and hyperlipidaemia had a significant influence on the occurrence of renal cysts, but not in the multivariate model. Of the 361 patients with renal cysts, 58 (16.1%) had bilateral and 26 (7.2%) had multiple unilateral cysts, with a mean (range) size of 26 (4-104) mm. The vast majority of cysts were classified as Bosniak I simple cysts; seven were Bosniak II and there was one Bosniak IV cyst. Associated renal pathologies included renal stones in 39 patients, hydronephrosis in nine, increased parenchymal echogenicity in 18, small atrophic kidneys in three, haematuria (not associated with other imaging abnormalities) in six, and a renal mass in one patient.

Conclusions: The prevalence of renal cysts detected by US in a health-screened population from the Middle East was 4.2%. Increasing age, male gender and a higher serum creatinine level were significant independent risk factors for cyst development. There was also a relatively high prevalence of associated renal pathologies (increased parenchymal echogenicity and stones).