Pathogenesis of acquired renal cysts in hemodialysis patients. The role of oxalate crystal deposition in renal tubules.

Although the mechanism responsible for the genesis of acquired renal cysts in hemodialysis patients has not been clearly defined, obstruction of the nephron by deposition of oxalate crystals may be an important factor. We performed this study to investigate this possibility. In 51 dialysis patients, the number and size of acquired cysts as well as kidney size were examined using sonography. Plasma oxalate levels were measured with capillary gas chromatography. Cysts were found in 6 of 18 (33.3%), 12 of 15 (75%), and 15 of 17 (88.2%) dialysis patients treated for 5, 10, and more than 10 years. The mean kidney size was significantly greater in hemodialysis patients with cysts than in those without cysts. There was a significant correlation between plasma oxalate levels and kidney size, particularly in patients dialyzed for longer periods (r = 0.638, P less than 0.01). Mean plasma oxalate levels of dialysis patients with renal cysts were significantly higher than those of noncystic patients (P less than 0.05). Although further evaluation is necessary to confirm these observations, our results suggest that oxalate crystal deposits in renal tubules secondary to hyperoxalemia in hemodialysis patients are a significant contributing factor to the formation of acquired renal cysts in these patients.