What are the causes and treatment options for orthostatic hypotension?

Causes and Treatment of Orthostatic Hypotension

Orthostatic hypotension should be managed with a stepwise approach beginning with non-pharmacological measures, followed by pharmacological treatments such as fludrocortisone or midodrine when symptoms persist despite conservative management. 1

Definition and Diagnosis

• Orthostatic hypotension is defined as a decrease in systolic blood pressure of ≥20 mmHg or a decrease in diastolic blood pressure of ≥10 mmHg within three minutes of standing 1
• Characterized by symptoms that develop upon standing and are relieved by sitting or lying down

Causes of Orthostatic Hypotension

Neurogenic Causes

• Diabetic autonomic neuropathy
• Parkinson's disease and other neurodegenerative disorders
• Multiple system atrophy
• Autoimmune disorders affecting autonomic function

Non-Neurogenic Causes

• Medications:

  • Vasodilators (nitrates, calcium channel blockers)
  • Diuretics
  • Antidepressants (especially tricyclics)
  • Antipsychotics
  • Alpha-blockers used for prostate conditions
  • Beta-blockers

• Volume Depletion:

  • Dehydration
  • Blood loss
  • Excessive diuresis

• Other Medical Conditions:

  • Heart failure
  • Adrenal insufficiency
  • Vitamin deficiencies (B12)
  • Thyroid dysfunction
  • Paraneoplastic syndromes

Treatment Approach

First-Line: Non-Pharmacological Interventions

1. Fluid and Salt Management:

   • Increased fluid intake of 2-3 liters of water daily 1
   • Increased salt intake (6-9g daily) 1

2. Physical Countermeasures:

   • Compression garments (thigh-high stockings with 30-40 mmHg pressure) 1
   • Physical counterpressure maneuvers (leg crossing, muscle tensing) 1
   • Head-up tilt sleeping (10° elevation) 1

3. Lifestyle Modifications:

   • Avoiding rapid position changes
   • Maintaining a cool environment 1
   • Small, frequent meals with reduced carbohydrate content 1
   • Structured exercise program with gradual reconditioning 1

Second-Line: Pharmacological Interventions

When non-pharmacological measures are insufficient, medications should be considered:

1. Fludrocortisone:

   • Dosage: 0.1mg daily 1
   • Mechanism: Volume expansion and increased sodium retention
   • Monitoring: Weight, electrolytes, supine hypertension

2. Midodrine:

   • Dosage: 5-20mg three times daily (last dose no later than 6 PM) 1, 2
   • Mechanism: Alpha-1 agonist causing vasoconstriction 2
   • Effects: Increases standing systolic BP by 15-30 mmHg, lasting 2-3 hours 2
   • Caution: Risk of supine hypertension; avoid in patients with baseline BP >180/110 mmHg 2
   • Starting dose: 2.5mg in patients with renal impairment 2

3. Other Medications:

   • Droxidopa: 100-600mg three times daily for neurogenic orthostatic hypotension 1
   • Pyridostigmine: 30mg 2-3 times daily for refractory cases 1
   • Octreotide: For refractory postprandial hypotension 1
   • Acarbose: For postprandial hypotension, particularly in autonomic dysfunction 1

Special Considerations

Monitoring

• Regular weight assessment and electrolyte monitoring 1
• Heart rate monitoring during position changes 1
• Blood pressure measurements in both supine and standing positions 1
• Symptom diary to track frequency and severity 1

Common Pitfalls to Avoid

1. Focusing on BP numbers rather than symptom improvement 1
2. Overlooking non-pharmacological measures before starting medications 1
3. Improper timing of medications (e.g., vasopressors too close to bedtime) 1
4. Inadequate monitoring for supine hypertension 1
5. Using medications that can worsen orthostatic hypotension (e.g., diuretics, vasodilators)

Special Populations

• Elderly: More vulnerable due to age-related changes in autonomic function 1
• Diabetic patients: Require focus on glucose control alongside orthostatic management 1
• Heart failure patients: Cautious use of volume-expanding agents 1
• Renal impairment: Start with lower doses of midodrine (2.5mg) 1, 2
• Patients on dialysis: Midodrine is removed by dialysis 2

Drug Interactions

• Avoid concomitant use of midodrine with:
  • Cardiac glycosides (risk of bradycardia) 2
  • Other vasoconstrictors (phenylephrine, ephedrine) 2
  • MAO inhibitors 2
  • Alpha-adrenergic blockers (antagonize effects) 2

Remember that the goal of treatment is to improve functional capacity and quality of life rather than achieving specific blood pressure targets.