[The Influence of Change in Body Water Distribution Caused by Changing Position Upon Nocturia in Older Men].

A total of 29 men 60 years and older (mean age 74 years) who complained at least once about nocturnal voiding and were diagnosed with nocturnal polyuria in the frequency volume chart (FVC) were enrolled in this study. Body water was measured by bioelectric impedance analysis just after lying down at 4 pm and after raising legs 30 minutes later. Nocturnal urine production was measured by FVC, and urine production per unit of time at first nocturnal voiding (urine volume at first nocturnal voiding/hours of undisturbed sleep (HUS) : UFN/HUS), urine production per unit of time during sleep (total nocturnal urine volume/hours of sleep : TNV/HS), etc was evaluated. Extra cellular water (ECW) of 0.19 l (4.0%) in legs was reduced caused by body position changing. There was a significant positive correlation between the amount of ECW in legs and UFN/HUS, TNV/HS (r＝0. 57, p＝0.001 ; r＝0. 38, p＝0.042, respectively). Moreover, UFN/HUS had a significant correlation with soft lean mass in legs, ECW in legs and daytime water intake. This study suggested that a change in leg fluids caused by a change in position results in increased urine production and decreased HUS.