Water and Sodium Balance By James L Lewis III, MD, Brookwood Baptist Health and Saint Vincent's Ascension Health, Birmingham Reviewed / Revised Apr 2022 | Modified Sep 2022 View Patient Education Topic Resources Total Body Water in Women... Total Body Water in Men... Total Body Water Estimation... Osmolality Estimator (serum) Fluid compartments in an... Overview of Hydration Body fluid volume and electrolyte concentration are normally maintained within very narrow limits despite wide variations in dietary intake, metabolic activity, and environmental stresses.