~60 mmol Na+/kg body mass
||OS. Andersen, "Cellular Electrolyte Metabolism", in Encyclopedia of metalloproteins, eds. Robert H Kretsinger Vladimir N Uversky E A Permi?a?kov, Springer 2013 pp.580-587 p.584 left column 2nd paragraph
||"Considering the distribution of the body water between the intracellular and extracellular compartments and the chemical composition of the compartments, one can deduce that most of the body’s Na+ is in the extracellular fluid, whereas most of the K+ is in the intracellular fluid. There are ~60 mmoles of Na+ per kg body mass: ~10% in the intracellular fluid. 50-60% in the extracellular fluid. and the rest in bone."