Changes in the fluid volume balance between intra- and extracellular water in a sample of Japanese adults aged 15–88 yr old: a cross-sectional study

Abstract

The fluid volume balance between intracellular water (ICW) and extracellular water (ECW) gradually changes with age and various medical conditions. Comprehension of these physiological changes would aid in clinical decision-making related to body fluid assessments. A total of 1,992 individuals (753 men and 1,239 women) aged ≥15 yr included in this study had their body composition measurements performed at training gyms in 2014. We developed a regression formula to assess the association of age with the ratio of ECW to ICW in these subjects. The mean ages of male and female subjects were 51.2 ± 15.2 and 57.4 ± 15.2 yr, and their mean body mass indexes were 23.4 ± 3.3 and 21.1 ± 2.8 kg/m, respectively. The total fluid volumes of male and female subjects were 39.6 ± 4.9 and 27.7 ± 3.0 liters, whereas the percent body fat mass per kilogram of body weight were 19 and 26%, respectively. The ECW-to-ICW ratio increased with age because of the steeper decrease in the ICW content than in the ECW content, especially after the age of 70 yr. The regression formulas used for calculating the age-adjusted ECW/ICW ratio were as follows: 0.5857 + 7.4334 × 10 × (age) in men and 0.6062 + 5.5775 × 10 × (age) in women. In conclusion, the fluid imbalance between ICW and ECW contents is driven by decreased cell volume associated with aging and muscle attenuation. Therefore, our proposed formula may serve as a useful assessment tool for the calculation of body fluid composition.

A Comparison of Body Composition, Residual Biological Function and Dialytic Treatment of 20 Males and 19 Females Undergoing Chronic Peritoneal Dialysis

“…The ratio of extracellular water/intracellular water adjusted by age was obtained using two formulae according to the gender. These formulae are reported in a paper by Japanese researchers [2]: 0.5857+7.4334 x106 x (age)2; for males and 0.6062 + 5.5775 x 106 x age2 for females. Although the formulae were developed based on a very different population, their application in the subjects of this study yielded suitable results.…”

Role of Changes in State of Bound Water and Tissue Stiffness in Development of Age-Related Diseases

“…A decrease in the ICW content with age proceeds with a higher rate than in the ECW content. Increase in ECW/ICW ratio accelerates after the age of 70 years [24].…”

Impact of extracellular-to-intracellular fluid volume ratio on albuminuria in patients with type 2 diabetes: A cross-sectional and retrospective cohort study

“…Body mass index (BMI), intracellular water (ICW), extracellular water (ECW), total body water (TBW), body fat mass, and skeletal muscle mass were measured with fasting state by BIA (18). ECW/ICW ratio and skeletal muscle index (SMI, kg/m 2 ) was calculated from the obtained data (19,20).…”