Hyponatremia

Abstract

In addition to the causes of gait disturbances in old age that were listed in the article I wish to mention another cause of gait disturbances that has hardly received any attention but is clinically highly relevant. Patients with mild chronic hyponatremia fall notably more frequently than patients with normal serum concentrations of sodium. Hyponatremia affects gait more strongly than a blood alcohol concentration of 0.6 g/L. Gait disturbances are reversible after the hyponatremia has been corrected (1). In older patients, hyponatremia is associated with fractures (2). Hyponatremia is twice as common in patients with fractures as in those admitted without fractures. The cause of the gait disturbance is “hyponatremic encephalopathy,” which is probably the result of a decrease of important, functional, intracellular osmolytes in the brain, such as glutamate and glutamine, in the context of volume adaptation of the brain (3). Further, signs of a reversible decrease in peripheral nerve conduction velocity has been observed in hyponatremia. According to a large study, 14.5% of patients have hyponatremia on admission to hospital (4). Often this is associated with certain medications. Often, patients develop hyponatremia while receiving treatment with hydrochlorothiazide (HCT), after taking medications that have a neurological effect (antidepressants), or while being treated with carbamazepine. It is likely that the number of hospital admissions owing to falls could be reduced if we paid more attention to hyponatremia and reacted appropriately. Diagnostic and therapeutic algorithms are available for this purpose.