Dear Sir, There have been few studies [1-6] on changes in kidney size in dialysis patients with autosomal dominant polycystic kidney disease (ADPKD). Conflicting results [1-6] have been reported in a few longitudinal studies. We examined the relationship between the duration of hemodialysis and kidney volume for the initial 5 years with frequent CT studies in each case. The kidney volume was estimated using the CT scan [7]. The CT scan was sequentially applied from the upper pole to the lower pole of the kidney. 8 ADPKD patients were studied: 5 females and 3 males. Their mean age was 48.6±8.8 years at the initiation of hemodialysis. Hemodialysis was performed 3 times week for 4 h each session, except for the initial 6 months when a 3-hour session was applied, using 1.3-2.1 m2 dialyzers. 68 CT scans were performed for the 8 patients beginning just before hemodialysis up to 5 years after the initiation of treatment. The data were expressed as mean±SD. The statistical significance was judged by the paired Student t test or the Wilcoxon signed-rank test. The kidney volumes at the start or just before the start of hemodialysis were remarkably different between patients. The values ranged from 1,068 to 5,452 ml (mean 3,086±1,214 ml)(fig. 1).

After the start of hemodialysis the kidney volume decreased in all 8 patients. The minimum volume was obtained 1 year after the start of hemodialysis in 3 patients, 2 years later in 2 patients, 3 years later in 2 patients and 4 years later in 1 patient (fig. 1). Thus, the minimum renal volume was 2,066±840 ml 23.4±16.0 months after the initiation of hemodialysis (p< O. 01). The kidney volume in ADPKD increased after the initial reduction and was 2,844±1,591 ml 53.7±15.1 months after the initiation of hemodialysis (p< 0.025)(fig. 1, 2). The increased volumes ranged from