Can stroke cause Syndrome of Inappropriate Antidiuretic Hormone (SIADH) secretion?

Stroke Can Cause SIADH

Yes, stroke can cause Syndrome of Inappropriate Antidiuretic Hormone (SIADH) secretion, and it is actually one of the more common causes of hyponatremia in stroke patients. 1, 2

Epidemiology and Prevalence

• Hyponatremia occurs in approximately 34-43% of patients with stroke 1, 2
• SIADH is the predominant cause of hyponatremia in stroke patients, accounting for 67-71% of hyponatremia cases 1, 2
• Cerebral Salt Wasting Syndrome (CSWS) is the second most common cause, representing about 33% of hyponatremia cases in stroke 2

Pathophysiology

• Stroke can trigger inappropriate release of antidiuretic hormone (ADH), leading to water retention and dilutional hyponatremia 3
• This inappropriate ADH secretion results in concentrated urine and decreased free water excretion despite hyponatremia 4
• Both ischemic and hemorrhagic strokes can cause SIADH, with some studies suggesting it may be more common in hemorrhagic stroke 2

Clinical Presentation and Diagnosis

• Patients with stroke-induced SIADH typically present with euvolemic hyponatremia 5
• Laboratory findings suggestive of SIADH include:
  • Serum sodium <135 mEq/L 1
  • Inappropriately high urine osmolality (>500 mosm/kg) relative to plasma osmolality 5
  • Urine sodium >20 mEq/L 5
  • Serum uric acid <4 mg/dL 5
• Distinguishing SIADH from CSWS is crucial as treatment approaches differ significantly 4, 6
  • SIADH: euvolemic state with water retention
  • CSWS: hypovolemic state with primary natriuresis 3

Management

• For SIADH in stroke patients, fluid restriction to 1L/day is the cornerstone of treatment 4, 6
• Severe symptomatic hyponatremia may require 3% hypertonic saline with careful monitoring 4
• The rate of sodium correction should not exceed 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome 4, 6
• Treatment of patients with specific conditions such as SIADH requires modifications to standard hydration protocols 4

Prognosis and Outcomes

• Hyponatremia can affect the outcome of stroke, particularly when caused by CSWS rather than SIADH 2
• Close monitoring of serum sodium is essential in all stroke patients to detect and manage hyponatremia promptly 2

Common Pitfalls

• Misdiagnosing SIADH as CSWS or vice versa can lead to inappropriate treatment 3
• Using fluid restriction in cerebral salt wasting can worsen outcomes 6
• Failing to recognize and treat the underlying cause of hyponatremia 6
• Overly rapid correction of chronic hyponatremia can lead to osmotic demyelination syndrome 6

Special Considerations

• Certain medications used in stroke management may also contribute to or exacerbate SIADH 7
• The location of stroke may influence the development of SIADH:
  • In hemorrhagic stroke with SIADH, right putamen hemorrhage was observed in 50% of cases 1
  • In ischemic stroke with SIADH, left middle cerebral artery territory infarcts were seen in 47% of cases 1