Disorders in sodium balance with consequent effect on osmolality come about mainly due to disturbances in water homeostasis rather than an abnormality of sodium intake or excretion” Maher and Macnab (2018).
Abstract:
Adequate tissue perfusion and cellular function is dependent on the maintenance of effective circulatory volume and serum osmolality, respectively. As sodium is the principal extracellular cation with the inability to pass freely across the cellular membrane, it therefore has the greatest effect on extracellular fluid osmolality. The extracellular fluid (ECF) volume can increase or decrease independent of the surrounding osmolality, indicating that control of plasma osmolality and volume occur through distinct physiological processes. Disorders in sodium balance with consequent effect on osmolality come about mainly due to disturbances in water homeostasis rather than an abnormality of sodium intake or excretion.
Reference:
Maher, W. and Macnab, R. (2018) Regulation of fluid and electrolyte balance. Anaesthesia & Intensive Care Medicine. March 29th. [epub ahead of print].
DOI: https://doi.org/10.1016/j.mpaic.2018.02.012