What is the workup for orthostatic (postural) hypotension?

Workup for Orthostatic Hypotension

The definitive workup for orthostatic hypotension requires measuring blood pressure after 5 minutes of rest in the supine or sitting position, followed by measurements at 1 minute and 3 minutes after standing, with a diagnosis confirmed by a sustained decrease in systolic BP ≥20 mmHg, diastolic BP ≥10 mmHg, or a decrease in systolic BP to <90 mmHg within 3 minutes of standing. 1, 2

Diagnostic Criteria and Measurement Technique

• Orthostatic hypotension is defined as a sustained decrease in systolic BP ≥20 mmHg, diastolic BP ≥10 mmHg, or a decrease in systolic BP to <90 mmHg within 3 minutes of standing 3, 1
• In patients with supine hypertension, a systolic BP drop ≥30 mmHg should be considered diagnostic 1
• Proper measurement technique requires:
  • Patient resting in supine or sitting position for 5 minutes 2
  • Baseline BP measurement using validated device with appropriate cuff size 2
  • Follow-up measurements at 1 minute and 3 minutes after standing 2
  • Maintaining the arm at heart level during all measurements 2
• Blood pressure should be measured in both arms at the initial visit, and the arm with higher BP (if difference >10 mmHg) should be used for subsequent measurements 3, 2
• Heart rate should be recorded simultaneously to assess baroreflex function and help differentiate between neurogenic and non-neurogenic causes 2, 4

Types of Orthostatic Hypotension

• Classical OH: occurs within 3 minutes of standing 1
• Initial OH: characterized by BP decrease >40 mmHg systolic or >20 mmHg diastolic within 15 seconds of standing, with recovery within 40 seconds 1
• Delayed OH: occurs beyond 3 minutes of standing with slow progressive decrease in BP 1

Diagnostic Workup

Initial Assessment

• Detailed history focusing on:
  • Symptom characteristics (dizziness, lightheadedness, blurred vision, weakness, fatigue, syncope) 5
  • Timing of symptoms in relation to standing 4
  • Medication review (antihypertensives, antidepressants, antipsychotics, diuretics) 5, 6
  • Comorbid conditions (diabetes, Parkinson's disease, multiple system atrophy) 4
• Physical examination:
  • Orthostatic vital sign measurement as described above 2
  • Cardiovascular examination for volume status and heart failure 7
  • Neurological examination for signs of autonomic dysfunction 8

Advanced Testing

• If standard orthostatic vital signs are non-diagnostic but clinical suspicion remains high:
  • Head-up tilt table testing at 60 degrees or more 5, 8
  • 24-hour ambulatory blood pressure monitoring to detect patterns of BP variability 3
• Laboratory evaluation to identify underlying causes:
  • Complete blood count (anemia) 6
  • Basic metabolic panel (electrolyte abnormalities, renal function) 6
  • Glucose (diabetes) 4
  • Thyroid function tests (hypothyroidism) 7
  • Morning cortisol (adrenal insufficiency) 7
• Specialized autonomic testing for suspected neurogenic OH:
  • Heart rate variability with deep breathing 8
  • Valsalva maneuver to assess baroreflex function 8
  • Sudomotor function tests 8
• Echocardiography if cardiac cause suspected (though diagnostic yield is low without clinical evidence of cardiac disease) 3
• ECG to rule out arrhythmias that may contribute to symptoms 3

Differential Diagnosis

• Neurogenic causes:
  • Primary autonomic failure (Parkinson's disease, multiple system atrophy) 3, 8
  • Secondary autonomic neuropathies (diabetes, amyloidosis) 3, 4
• Non-neurogenic causes:
  • Medications (antihypertensives, vasodilators, diuretics) 5, 6
  • Volume depletion (dehydration, blood loss) 5
  • Cardiac insufficiency (heart failure, arrhythmias) 7
  • Venous pooling (prolonged bed rest, varicose veins) 7

Clinical Pearls and Pitfalls

• Orthostatic hypotension is associated with increased cardiovascular risk, falls, and up to 50% increase in all-cause mortality 6
• Symptoms depend more on the absolute BP level than the magnitude of the fall 1
• Many patients with orthostatic hypotension are asymptomatic despite significant BP drops 4
• The presence of supine hypertension complicates management and requires careful medication selection 8
• Pseudohypertension in elderly patients with calcified arteries may lead to overtreatment and iatrogenic orthostatic hypotension 3
• Consider delayed orthostatic hypotension by extending standing time beyond 3 minutes if symptoms suggest OH but initial testing is negative 1