The etiology of the often-observed fall of the serum sodium following operation or severe trauma has been principally related to two possible factors: (1) dilution of the extracellular fluid secondary to the use of parenteral fluids, and (2) disturbances in the integrity of the cell membrane which permit augmented increments of intracellular water and electrolyte to pass into the extracellular fluid and a transfer of extracellular sodium into the cells of the various body tissues.2,4,9,10 Regardless of the relative contributions of these two factors to the observed phenomenon of sodium fall, it is recognized that the serum sodium is restored to previously observed normal levels, without sodium salt administration, provided that internal homeostasis is supported by an early adequate return of oral intake and that extrarenal loss of body fluids is not of a clinical significance.
Modifications of internal exchange between the constituents of the intracellular and of the
ALMOND CH, BERRY REL. Significance of the Fall of Serum Sodium Following Operative Trauma. AMA Arch Surg. 1958;77(3):345-355. doi:10.1001/archsurg.1958.01290030045006