Although it was expected that body water turnover (WT) changes with growth, the extent of these changes is not clear. This study compared body water turnover between children and young men. Six children (6.0±2.6yr) and eight young men (21.1±1.4yr) participated in this study. Total body water and body water turnover were measured using the deuterium (D_2O) dilution technique. A urine sample was obtained every day for 10 days after oral administration of D_2O. The day-by-day concentrations were used to calculate the biological half-life of D_2O and body water turnover. Biological half-life of D_2O was significantly shorter in children than in young men (5.17±0.87 days vs. 7.66±0.93 days, P<0.05), and percentage of body water turnover was significantly higher in children than in young men (13.69±1.98 % vs. 9.17±1.08 %, P<0.05). Body water turnover, expressed quantitatively, was also greater in children than in young men (88.3±15.2 ml/kg/day vs. 56.3±83ml/kg/day, P<0.05). These results indicate that children have a higher body water turnover than young men, and suggest that body water turnover drastically decreases with growth.
