RESUMO
Hyponatremia is the most frequent electrolyte disorder found in clinical practice, particularly in hospitalized elderly patients, where it is associated with fractures, falls, hospital readmission, prolonged hospital stay and increased mortality. Pathophysiologically, hyponatremia can be induced by the reduction in sodium or potassium body content, and/or the increase in water body content. Sarcopenia is an ageing-associated progressive and generalized loss of musculoskeletal mass and strength which leads to low physical performance, particularly in the frail elderly. Since muscle mass is the main potassium body store, this condition usually represents a reduced body potassium content. In the present article it is hypothesized that sarcopenia, as a cause of low potassium body content, could induce or co-induce hyponatremia, particularly in elderly individuals suffering from frailty phenotype.