Figure 1: The formula of Adrogué et al. (33) offers an easy way to estimate the effect of 1 liter of any infusate on change in serum sodium concentration. Total body water is calculated as a fraction of body weight (children: 0.6; non-elderly women: 0.5; elderly women: 0.45; non-elderly men: 0.6; elderly men: 0.5).