What are the diagnostic criteria for postural orthostatic tachycardia syndrome (POTS)?

POTS Diagnostic Criteria

POTS is diagnosed by demonstrating a sustained heart rate increase of ≥30 bpm (≥40 bpm in adolescents aged 12-19 years) within 10 minutes of standing or head-up tilt, occurring in the absence of orthostatic hypotension, accompanied by symptoms of orthostatic intolerance that have persisted for at least 3 months (6 months in children). 1, 2

Core Diagnostic Requirements

All five components must be present for diagnosis 2:

1. Heart Rate Criteria

• Adults: Sustained increase of ≥30 bpm within 10 minutes of standing 3, 1, 2
• Adolescents (12-19 years): Sustained increase of ≥40 bpm within 10 minutes of standing 3, 1, 2
• Standing heart rate often exceeds 120 bpm, though this absolute value is not required for diagnosis 1, 2
• The diagnostic criterion is based on the heart rate increment, not the absolute standing heart rate 1

2. Blood Pressure Criteria

• Orthostatic hypotension must be absent 3, 1, 2
• No sustained systolic blood pressure drop of ≥20 mm Hg 1, 2
• No sustained diastolic blood pressure drop of ≥10 mm Hg 1, 2
• Blood pressure criteria must be assessed within 3 minutes of standing 3, 1

3. Symptom Profile

Frequent symptoms of orthostatic intolerance that develop upon standing and improve when sitting or lying down 1, 2:

• Lightheadedness or dizziness 3, 1
• Palpitations and tremulousness 3, 1
• Generalized weakness and fatigue 3, 1
• Blurred vision or visual disturbances 3, 1
• Exercise intolerance 3, 1
• "Brain fog" or cognitive difficulties 1
• Headache and chest pain 1
• Important: Syncope is rare in POTS and typically occurs only when vasovagal reflex activation is triggered, not from POTS itself 3, 2, 4

4. Duration Requirement

• Symptoms must persist for at least 3 months in adults 1, 2
• Symptoms must persist for at least 6 months in children 1, 2

5. Exclusion of Alternative Causes

Must exclude conditions that can mimic POTS 1, 2:

• Dehydration or volume depletion 1
• Medications (cardioactive drugs, diuretics, vasodilators, venodilators) 1
• Hyperthyroidism 1
• Anorexia nervosa 1
• Primary anxiety disorders 1
• Cardiac arrhythmias (supraventricular or ventricular tachyarrhythmias) 1

Diagnostic Testing Approach

Active Stand Test (Preferred Initial Test)

Perform a 10-minute active stand test with continuous monitoring 1:

Pre-test preparation:

• Patient should fast for 2-4 hours before testing 1
• Avoid nicotine, caffeine, theine, or taurine-containing drinks on the day of examination 3, 1
• Testing should be performed in a quiet environment with temperature controlled between 21-23°C 3, 1
• Tests should ideally be performed before noon 3

Testing protocol:

• Measure blood pressure and heart rate after 5 minutes of lying supine 1
• Record immediately upon standing, and at 2,5, and 10 minutes after standing 1
• Patient must stand quietly for the full 10 minutes as heart rate increase may take time to develop 1
• Document any symptoms that occur during the test 1

Tilt-Table Testing (When Active Stand Test is Inconclusive)

• Perform head-up tilt at 60-70 degrees for 20-45 minutes if active stand test is inconclusive but clinical suspicion remains high 1
• Same heart rate and blood pressure criteria apply during head-up tilt 3, 1
• Useful to distinguish POTS from delayed orthostatic hypotension 1
• A positive test demonstrates predisposition to orthostatic tachycardia but must be correlated with the patient's typical symptoms 1

Additional Diagnostic Workup

Essential Testing

• 12-lead ECG to rule out arrhythmias or conduction abnormalities 1
• Thyroid function tests to exclude hyperthyroidism 1
• Comprehensive medication review, especially cardioactive drugs 1
• Detailed medical history, including family history of similar conditions 1

Screening for Associated Conditions

• Joint hypermobility: Use Beighton score (≥6/9 points in children before puberty) 1
• Iron deficiency: Check ferritin levels, particularly in hypovolemic subtype 1
• Post-viral POTS: Consider in patients with recent COVID-19 or other viral infections 1

Critical Diagnostic Pitfalls to Avoid

Common Errors

• Failure to perform the full 10-minute stand test may miss delayed heart rate increases 1
• Using adult heart rate criteria (≥30 bpm) in adolescents aged 12-19 leads to overdiagnosis; must use ≥40 bpm threshold 1
• Not maintaining proper fasting conditions can affect test results and lead to misdiagnosis 1
• Dismissing the diagnosis because standing heart rate doesn't exceed 120 bpm; the diagnostic criterion is based on the increment (≥30 bpm), not the absolute standing heart rate 1
• Not distinguishing POTS from inappropriate sinus tachycardia or other tachyarrhythmias 1

Important Clinical Considerations

• A negative stand test does not exclude POTS if clinical suspicion remains high—consider tilt-table testing in these cases 1
• Significant patients with POTS may not present orthostatic symptoms during testing despite having chronic daily symptoms; this may be related to low diastolic blood pressure and abnormal compensatory responses 5
• Psychogenic pseudosyncope can occur in young females with POTS-like symptoms, often with history of abuse, underscoring the importance of distinguishing true autonomic dysfunction from functional presentations 1

Associated Conditions to Evaluate

POTS may be associated with 3, 1, 2:

• Deconditioning (often both cause and consequence) 1
• Chronic fatigue syndrome/ME/CFS 1
• Joint hypermobility syndrome 3, 1, 2
• Recent infection or trauma 3, 2
• Post-acute sequelae of COVID-19 1