P-5 Change in Body Water Turnover with Age and Its Association with Physical Activity and Creatinine Clearance

The objective of this study was to compare the body water turnover (WT) between elderly and young men and to evaluate its association with physical activity and creatinine clearance. Eight elderly men (64.3 ±2.4 yr) and eight young men (20.8± 1.5 yr) participated in this study. All the subjects were free of medical problems, but did not have any regular physical activities. The total body water in each subject was determined using deuterium oxide (D2O) as a tracer for water. After D2O administration for measurement of total body water, WT was evaluated during ten (10) consecutive days. WT was lower in elderly than in young men (7.8± 1.4% vs. 9.5± 1.3%, p＜0.05). WT was significantly correlated with daily physical activity (p＜0.05), but not with creatinine clearance. These results indicated that WT decreased with age, and was related to physical activity level but not to kidney function.