Hyponatremia in Acute Stroke Patients: Pathophysiology, Clinical Significance, and Management Options

Background: Hyponatremia is frequent in acute stroke patients, and it is associated with worse outcomes and increased mortality.

Summary: Nonstroke-related causes of hyponatremia include patients' comorbidities and concomitant medications, such as diabetes mellitus, chronic kidney disease, heart failure, and thiazides. During hospitalization, "inappropriate" administration of hypotonic solutions, poor solute intake, infections, and other drugs, such as mannitol, could also lower sodium levels in patients with acute stroke. On the other hand, secondary adrenal insufficiency due to pituitary ischemia or hemorrhage, syndrome of inappropriate antidiuretic hormone secretion, and cerebral salt wasting are additional stroke-related causes of hyponatremia. Although it is yet unclear whether the appropriate restoration of sodium level improves outcomes in patients with acute stroke, the restoration of the volume depletion remains the cornerstone of treatment in hypovolemic hyponatremia. In case of hyper- and euvolemic hyponatremia, apart from the correction of the underlying cause (e.g., withdrawal of an offending drug), fluid restriction, administration of hypertonic solution, loop diuretics, and vasopressin-receptor antagonists (vaptans) are among the therapeutic options. Key Messages: Hyponatremia is frequent in patients with acute stroke. The plethora of underlying etiologies warrants a careful differential diagnosis which should take into consideration comorbidities, concurrent medication, findings from the clinical examination, and laboratory measurements, which in turn will guide management decisions. However, it is yet unclear whether the appropriate restoration of sodium level improves outcomes in patients with acute stroke.