Is hypernatremia (elevated sodium levels) or hyponatremia (low sodium levels) worse in patients with stroke (cerebrovascular accident)?

From the Guidelines

Hyponatremia is generally considered worse than hypernatremia in patients with stroke, as it is more common and associated with increased mortality, longer hospital stays, and poorer functional outcomes. According to the guidelines for the management of aneurysmal subarachnoid hemorrhage by the American Heart Association/American Stroke Association 1, hyponatremia has been chronologically associated with the onset of sonographic and clinical vasospasm, and can develop from different mechanisms after aSAH, including the syndrome of cerebral salt wasting. This condition can provoke volume contraction and is an independent risk factor for poor outcome.

Some key points to consider in the management of hyponatremia in stroke patients include:

• The use of hypertonic saline solution, which appears to increase regional cerebral blood flow, brain tissue oxygen, and pH in patients with high-grade aSAH 1
• The potential benefits of fludrocortisones in correcting hyponatremia and fluid balance, as suggested by randomized, controlled trials 1
• The importance of careful fluid restriction and discontinuation of contributing medications in the management of hyponatremia
• The need for cautious correction of sodium levels to avoid osmotic demyelination syndrome, with a recommended correction rate of no more than 8-10 mEq/L in 24 hours.

While hypernatremia is also a concern in stroke patients, the available evidence suggests that hyponatremia is the more significant electrolyte disturbance in terms of prevalence and impact on patient outcomes 1.

From the Research

Comparison of Hypernatremia and Hyponatremia in Stroke Patients

• Hyponatremia is associated with worse clinical outcomes in stroke patients, as shown in a study published in The Journal of clinical endocrinology and metabolism 2.
• Persistent hyponatremia is associated with worse functional outcome in hospitalized acute stroke patients 2.
• Hyponatremia can cause focal neurological complaints and deficits, mimicking acute ischemic stroke, as reported in The American journal of emergency medicine 3.
• The incidence of hyponatremia in stroke patients is significant, with one study finding an incidence of 35% 4.
• Hyponatremia, especially when caused by cerebral salt wasting syndrome (CSWS), affects the outcome of stroke, as found in a study published in Annals of Indian Academy of Neurology 4.
• Sodium and water perturbations, including both hyponatremia and hypernatremia, are common in patients who had an acute stroke and are associated with worse outcomes and increased mortality 5.
• There is currently no consensus on the management of sodium and water perturbations in patients who had an acute stroke, highlighting the need for further research and guidelines 5.

Clinical Relevance and Management

• The restoration of volume depletion remains the cornerstone of treatment in hypovolemic hyponatremia 6.
• In cases of hyper- and euvolemic hyponatremia, treatment options include fluid restriction, administration of hypertonic solution, loop diuretics, and vasopressin-receptor antagonists (vaptans) 6.
• Close monitoring of serum sodium is essential in all patients admitted with stroke, and efforts should be made to determine the cause of hyponatremia to properly manage these patients 4.

Pathogenesis and Etiology

• Hyponatremia in acute stroke patients can be caused by various factors, including syndrome of inappropriate antidiuretic hormone secretion (SIADH), cerebral salt wasting syndrome (CSWS), and non-stroke-related causes such as comorbidities and concomitant medications 6, 4.
• The development of endocrine consequences after an acute stroke, including secondary adrenal insufficiency and diabetes insipidus, can also contribute to sodium and water perturbations 5.