How is postural hypotension diagnosed?

How to Diagnose Postural Hypotension

Diagnose orthostatic hypotension by measuring blood pressure after 5 minutes of supine or seated rest, then at 1 minute and 3 minutes after standing—a drop of ≥20 mmHg systolic or ≥10 mmHg diastolic (or systolic BP <90 mmHg) within 3 minutes confirms the diagnosis. 1

Measurement Technique

Patient Preparation

• Have the patient rest in supine or sitting position for 5 minutes before baseline measurement 2, 3
• The supine position is preferred for greater sensitivity, though sitting is more practical in clinical settings 3
• Patients should fast for 3 hours before testing and avoid nicotine, caffeine, theine, or taurine-containing drinks on the day of examination 2
• Testing should occur in a temperature-controlled environment (21-23°C) 2

Measurement Protocol

• Use a validated and calibrated blood pressure device with appropriate cuff size based on arm circumference 1
• Measure BP in both arms at the first visit; if systolic BP differs by >10 mmHg between arms, use the arm with higher BP for all subsequent measurements 1, 3
• Maintain the arm at heart level with the patient's back and arm supported during all measurements 3
• Take baseline BP and heart rate after the 5-minute rest period 2, 3
• Measure BP and heart rate at 1 minute and 3 minutes after standing 1, 2
• Keep the arm at heart level during standing measurements 2, 3

Diagnostic Criteria

Classical Orthostatic Hypotension

• Sustained decrease in systolic BP ≥20 mmHg, OR
• Diastolic BP ≥10 mmHg, OR
• Systolic BP falling to <90 mmHg within 3 minutes of standing 1, 2
• In patients with supine hypertension, a systolic BP drop ≥30 mmHg should be considered diagnostic 2

Subtypes to Consider

Initial Orthostatic Hypotension:

• BP decrease >40 mmHg systolic and/or >20 mmHg diastolic within 15 seconds of standing 1
• BP spontaneously and rapidly returns to normal, so hypotension period is brief (<40 seconds) but may still cause syncope 1

Delayed Orthostatic Hypotension:

• BP drop meeting criteria but occurring beyond 3 minutes of standing 1
• Characterized by slow progressive decrease in BP 1
• If initial 3-minute testing is negative but symptoms suggest OH, extend standing time beyond 3 minutes 2

When Office Testing is Insufficient

Head-Up Tilt Table Testing

• Perform passive head-up tilt testing (at least 60 degrees) if active standing test is negative but history is suggestive of OH 1, 4
• Particularly useful in patients with motor impairment who cannot stand safely 4, 5
• Tilt table testing is more sensitive than sit-stand testing, which has very low diagnostic accuracy (sensitivity only 15.5%) 6

Ambulatory Blood Pressure Monitoring

• Routine ABPM is not currently suitable for formally assessing orthostatic hypotension 1
• However, it may help in some cases, particularly when accompanied by a patient symptom diary 1

Important Clinical Considerations

Heart Rate Response

• Record heart rate during all measurements and check for arrhythmias 3
• Orthostatic HR increase is blunted in neurogenic OH (usually <10 beats per minute) because autonomic HR control is impaired 1
• In contrast, orthostatic HR increase is preserved or enhanced in OH due to hypovolemia 1

Measurement Device Limitations

• Continuous BP measurement devices are preferred over interval devices for accurate diagnosis—interval measurements have low concordance with continuous measurements (positive agreement only 59.5%) 7
• Oscillometric BP monitors are not always accurate in the presence of atrial fibrillation; use multiple auscultatory measurements instead 1

Common Pitfalls

• Symptoms alone are unreliable: Only 32.8% of patients with documented postural hypotension experience postural dizziness, so you cannot diagnose or exclude OH based on symptoms alone 8
• Symptoms depend more on the absolute BP level than the magnitude of the fall 1, 2
• Sit-stand testing has very low diagnostic accuracy (sensitivity 15.5%, specificity 89.9%) compared to head-up tilt testing—do not rely on this method 6

When to Screen

• Assess for orthostatic hypotension before starting or intensifying BP-lowering medication, particularly in older patients 3
• Screen patients with symptoms suggestive of OH (dizziness, lightheadedness, visual disturbances, syncope after standing) 2
• OH is present in approximately 10% of all hypertensive adults and up to 50% of older institutionalized adults 1