What is the initial workup and management for a patient presenting with dizziness and orthostatic hypotension?

Initial Workup and Management for Dizziness and Orthostatic Hypotension

The initial workup for a patient with dizziness and orthostatic hypotension should include assessment of volume status, orthostatic blood pressure changes, medication review, and targeted laboratory testing, followed by non-pharmacological interventions as first-line treatment and pharmacological therapy for persistent symptoms. 1, 2

Diagnosis and Initial Assessment

• Orthostatic hypotension is defined as a decrease in systolic blood pressure ≥20 mmHg or diastolic blood pressure ≥10 mmHg within 3 minutes of standing compared to supine position 2, 3
• Measure blood pressure after 5 minutes of lying/sitting and then at 1 and 3 minutes after standing to diagnose orthostatic hypotension 2
• Initial laboratory evaluation should include complete blood count, urinalysis, serum electrolytes (including calcium and magnesium), blood urea nitrogen, serum creatinine, fasting blood glucose, lipid profile, liver function tests, and thyroid-stimulating hormone 1
• Twelve-lead electrocardiogram and chest radiograph should be performed to rule out cardiac causes 1
• Assess for symptoms including dizziness, lightheadedness, blurred vision, weakness, fatigue, and syncope upon standing 1, 3
• Evaluate for neurogenic causes (multiple system atrophy, pure autonomic failure, autonomic neuropathies) versus non-neurogenic causes (dehydration, medications) 1

Non-Pharmacological Management (First-Line)

• Identify and discontinue or modify hypotensive medications when possible, particularly diuretics and vasodilators 1
• Increase fluid intake (≥480 mL of water with peak effect 30 minutes after consumption) and salt intake (6-9g daily) if not contraindicated by other conditions 1, 2
• Implement physical counter-maneuvers such as leg crossing, stooping, squatting, and tensing muscles to temporarily increase blood pressure 2, 4
• Recommend compression garments (at least thigh-high and preferably including the abdomen) to improve orthostatic symptoms 1, 5
• Advise smaller, more frequent meals to reduce post-prandial hypotension 2, 4
• Encourage gradual staged movements with postural change and avoid sudden position changes 2, 6
• Elevate the head of the bed during sleep (to prevent supine hypertension) 2
• Maintain physical activity to prevent deconditioning 2, 5

Pharmacological Management (When Non-Pharmacological Measures Fail)

1. First-line medications:

   • Midodrine: Alpha-1 agonist that increases vascular tone

     • Dosing: Start at 2.5-5 mg three times daily (last dose no later than 6 PM to avoid supine hypertension)
     • Monitor for supine hypertension, urinary retention, and bradycardia 1, 7

   • Fludrocortisone: Increases plasma volume

     • Dosing: Start at 0.05-0.1 mg daily, titrate to 0.1-0.3 mg daily
     • Monitor for supine hypertension, edema, hypokalemia, and heart failure 1, 2

   • Droxidopa: Converts to norepinephrine, increasing blood pressure

     • Particularly effective for neurogenic orthostatic hypotension 1, 2

2. Combination therapy:

   • Consider combination of midodrine and fludrocortisone for non-responders to monotherapy 2

Special Considerations and Monitoring

• Monitor for supine hypertension (BP >200 mmHg systolic), a common adverse effect of pharmacological treatment 7
• Use caution when combining medications that cause vasoconstriction (phenylephrine, ephedrine, dihydroergotamine) 7
• Use midodrine with caution in patients with urinary retention, renal impairment, or hepatic impairment 7
• Evaluate treatment efficacy based on symptom improvement rather than achieving a target blood pressure 8
• Consider referral for autonomic function testing if orthostatic hypotension is accompanied by insufficient heart rate increase, suggesting autonomic dysfunction 6

Treatment Algorithm

1. Confirm orthostatic hypotension with appropriate BP measurements
2. Identify and address reversible causes (medications, dehydration)
3. Implement non-pharmacological measures for all patients
4. If symptoms persist despite non-pharmacological treatment:
   • Add midodrine for patients without urinary retention issues
   • Add fludrocortisone for patients without heart failure or significant edema
   • Consider droxidopa for neurogenic orthostatic hypotension
5. Monitor for symptom improvement and adverse effects, particularly supine hypertension
6. Adjust treatment based on symptomatic response rather than BP measurements 1, 2, 3