Disorders of plasma sodium concentration subject cells to hypo- or hypertonic stress, potentially causing significant cellular dysfunction. The osmoregulatory system maintains plasma sodium within a narrow physiological range (135–142 mmol/L) by modulating water intake and excretion. Due to the permeability of cell membranes to water via aquaporins, osmotic equilibrium must be preserved to prevent cell swelling or shrinkage [1,2]. This balance is actively sustained by the Na⁺/K⁺-ATPase, which extrudes sodium and imports potassium to maintain ionic gradients.
