What is the complete workup for orthostatic (low blood pressure when standing) hypotension?

Complete Workup for Orthostatic Hypotension

Diagnostic Criteria and Measurement Technique

Orthostatic hypotension is diagnosed when systolic blood pressure drops ≥20 mmHg or diastolic blood pressure drops ≥10 mmHg within 3 minutes of standing, or when systolic BP falls to <90 mmHg. 1, 2 In patients with supine hypertension, use a threshold of ≥30 mmHg systolic drop. 2

Proper Measurement Protocol

• Patient preparation: Fast for 3 hours before testing; avoid nicotine, caffeine, theine, or taurine-containing drinks on the day of examination 2, 3
• Environment: Temperature-controlled room at 21-23°C 2, 3
• Equipment: Use a validated, calibrated blood pressure device with appropriate cuff size based on arm circumference 2, 3
• Baseline measurement: Patient rests supine (preferred for sensitivity) or sitting for 5 minutes before initial BP and heart rate measurement 2, 3
• Standing measurements: Measure BP and heart rate at 1 minute and 3 minutes after standing, maintaining the arm at heart level during all measurements 2, 3
• Bilateral assessment: 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 2, 3

Critical pitfall: Standard interval BP devices have low concordance with continuous measurements—use continuous BP monitoring devices when available for accurate diagnosis. 2

Classification of Orthostatic Hypotension Subtypes

Classical Orthostatic Hypotension

• BP drops immediately after standing with a "concave" curve pattern 1, 2
• Sustained reduction meeting diagnostic criteria within 3 minutes 1
• Heart rate response distinguishes neurogenic from non-neurogenic causes 1, 2

Initial (Immediate) Orthostatic Hypotension

• BP decrease >40 mmHg systolic and/or >20 mmHg diastolic within 15 seconds of standing 1, 2
• Transient with rapid recovery 1

Delayed Orthostatic Hypotension

• BP drop meeting criteria but occurring beyond 3 minutes of standing 1, 2
• More variable pattern of BP and heart rate decrease than classical OH 2
• Extend standing time beyond 3 minutes if symptoms suggest OH but initial testing is negative 2

Neurogenic vs. Non-Neurogenic OH

• Neurogenic OH: Blunted heart rate increase (usually <10 bpm) due to impaired autonomic HR control 1, 2
• Non-neurogenic OH: Appropriate compensatory heart rate increase (>10% or ≥15-20 bpm) 1

Initial Clinical Evaluation

History Taking

Symptom assessment:

• Dizziness, lightheadedness, visual disturbances (tunnel vision, graying out), weakness, fatigue 1, 4
• Syncope, presyncope, palpitations, dyspnea, chest pain 1, 4
• Coat hanger syndrome (neck and shoulder pain) 4
• Timing and triggers of symptoms (postural changes, meals, exercise, heat exposure) 4, 5

Medication review:

• Diuretics, vasodilators, alpha-blockers, antihypertensives 2, 6
• Tricyclic antidepressants, phenothiazines, alcohol 2, 6
• Dopaminergic agents, MAO inhibitors 6, 5

Comorbidity assessment:

• Diabetes mellitus (autonomic neuropathy) 2, 4
• Parkinson's disease, multiple system atrophy, pure autonomic failure 2, 4
• Cardiac disease, heart failure 1, 5
• Volume depletion, blood loss, dehydration 1, 6
• Amyloidosis, autoimmune disorders 2, 5

Physical Examination

• Supine hypertension: Common in neurogenic OH; check for elevated supine BP 1, 2
• Cardiac examination: Assess for structural heart disease, arrhythmias, murmurs 1, 5
• Neurological examination: Evaluate for Parkinsonian features, peripheral neuropathy, autonomic dysfunction 2, 5
• Volume status: Assess for dehydration, anemia, bleeding 6, 5

Laboratory and Diagnostic Testing

Basic Laboratory Panel

• Complete blood count: Rule out anemia 1, 6
• Serum electrolytes (sodium, potassium, calcium): Assess for electrolyte disturbances 1, 6
• Serum creatinine with eGFR: Evaluate renal function 1, 6
• Fasting blood glucose: Screen for diabetes 1, 6
• Thyroid-stimulating hormone: Rule out thyroid dysfunction 1, 6

Electrocardiogram

• 12-lead ECG: Rule out arrhythmias, conduction abnormalities, structural heart disease 2, 5
• Monitor heart rate and rhythm during orthostatic testing 2, 3

Advanced Testing (When Indicated)

24-hour ambulatory blood pressure monitoring:

• Detect patterns of BP variability and supine hypertension 2
• Assess diurnal BP variations 2

Echocardiography:

• Only if cardiac cause suspected based on clinical evidence 2
• Low diagnostic yield without clinical indicators of cardiac disease 2

Head-up tilt table testing:

• Indicated when bedside orthostatic vital signs are nondiagnostic but clinical suspicion remains high 6, 4
• Useful for assessing treatment response in autonomic disorders 6
• Perform at ≥60-degree head-up tilt 4, 5
• Provides continuous BP and heart rate monitoring to distinguish reflex syncope from OH 1

Autonomic function testing:

• Valsalva maneuver, deep breathing test, quantitative sudomotor axon reflex test 5
• Helps differentiate neurogenic from non-neurogenic causes 5

Pattern Recognition on Continuous Monitoring

Reflex Syncope (to differentiate from OH)

• Latency period after head-up tilt before BP drops 1
• "Convex" BP decrease curve with accelerating rate of drop 1
• Heart rate decreases along with BP 1
• Rapid recovery after returning to supine position 1

Classical Orthostatic Hypotension

• Immediate BP drop after standing with "concave" curve 1, 2
• Decreasing rate of BP drop over time 1
• May stabilize at lower level or continue gradual decline 1
• Impaired heart rate variability in neurogenic OH 1, 2

Etiologic Classification

Neurogenic Causes

• Primary autonomic failure: Parkinson's disease, multiple system atrophy, pure autonomic failure 2, 4
• Secondary autonomic neuropathies: Diabetes mellitus, amyloidosis, autoimmune disorders 2, 4

Non-Neurogenic Causes

• Hypovolemia: Dehydration, blood loss, anemia 1, 6
• Medications: Diuretics, vasodilators, antihypertensives, alcohol 2, 6
• Cardiac: Impaired venous return, cardiac insufficiency, arrhythmias 7, 5
• Endocrine: Adrenal insufficiency, hypothyroidism 6, 5

Situational Syncope (differential diagnosis)

• Associated with specific triggers: micturition, coughing, defecation 2
• Distinct from positional OH 2

Clinical Pearls and Pitfalls

• Symptoms depend more on absolute BP level than magnitude of fall 2
• Pseudohypertension in elderly patients with calcified arteries may lead to overtreatment and iatrogenic OH 2
• OH prevalence is approximately 10% in hypertensive adults and up to 50% in older institutionalized adults 2
• BP cannot be measured reliably in atrial fibrillation using standard instruments 3
• In heart failure patients with high filling pressures, standing may paradoxically improve hemodynamics and increase systolic BP 3
• Assess for OH before starting or intensifying BP-lowering medications, particularly in older patients 3