What is the initial step in diagnosing a patient suspected of having Postural Orthostatic Tachycardia Syndrome (POTS)?

Testing for Postural Orthostatic Tachycardia Syndrome (POTS)

Perform a 10-minute active stand test with continuous heart rate and blood pressure monitoring—this is the initial diagnostic step for suspected POTS. 1

Diagnostic Criteria

POTS is diagnosed by demonstrating a sustained heart rate increase of ≥30 beats per minute (≥40 bpm in adolescents aged 12-19 years) within 10 minutes of standing or head-up tilt, in the absence of orthostatic hypotension, accompanied by symptoms of orthostatic intolerance. 1

Key Requirements:

• Heart rate criteria: ≥30 bpm increase in adults, ≥40 bpm in adolescents 12-19 years 1
• Standing heart rate: Often exceeds 120 bpm 1
• No orthostatic hypotension: Systolic BP drop must be <20 mmHg and diastolic BP drop <10 mmHg within 3 minutes of standing 1
• Symptom presence: Orthostatic intolerance symptoms (light-headedness, palpitations, tremor, weakness, blurred vision, fatigue) must occur with standing and improve with sitting/lying 1

Step-by-Step Testing Protocol

Active Stand Test Procedure

Measure blood pressure and heart rate after 5 minutes of lying supine, then record immediately upon standing and at 2,5, and 10 minutes after standing. 1

Critical execution points:

• The patient must stand quietly and motionless for the full 10 minutes—heart rate increase may take time to develop 1
• Document all symptoms occurring during the test 1
• Confirm absence of orthostatic hypotension (systolic BP drop ≥20 mmHg or diastolic BP drop ≥10 mmHg within 3 minutes) 1, 2

Testing Environment Requirements

Conduct testing in a quiet, temperature-controlled room between 21-23°C. 3, 1

Pre-test preparation:

• Patient must fast for 3 hours before testing 3, 1
• Avoid nicotine, caffeine, theine, or taurine-containing drinks on the day of examination 3, 1
• Ideally perform testing before noon 1

When to Use Tilt-Table Testing

If the active stand test is inconclusive but clinical suspicion remains high, proceed to tilt-table testing. 1

The tilt-table test uses the same diagnostic criteria (≥30 bpm increase without orthostatic hypotension) but provides more controlled conditions and continuous monitoring. 3, 1

Essential Complementary Evaluation

Before confirming POTS, exclude alternative diagnoses:

Mandatory Initial Workup:

• 12-lead ECG: Rule out arrhythmias or conduction abnormalities 1
• Thyroid function tests: Exclude hyperthyroidism 1
• Medication review: Identify cardioactive drugs that could cause tachycardia 1
• Detailed medical history: Including family history of similar conditions 1

Symptoms to Document:

• Dizziness, light-headedness, weakness, fatigue, lethargy 1
• Palpitations and sinus tachycardia 1
• Visual disturbances (blurring, tunnel vision) 1
• Cognitive difficulties ("brain fog") 1
• Headache and chest pain 1
• Gastrointestinal dysfunction 1

Critical Pitfalls to Avoid

Stopping the stand test before 10 minutes is the most common error—delayed heart rate increases will be missed. 1

Additional pitfalls:

• Failing to distinguish POTS from inappropriate sinus tachycardia or other tachyarrhythmias 1
• Not excluding secondary causes: dehydration, medications, primary anxiety disorder, eating disorders 1
• Using adult criteria (≥30 bpm) in adolescents instead of pediatric criteria (≥40 bpm for ages 12-19), which leads to overdiagnosis 1
• Diagnosing POTS when orthostatic hypotension is present—POTS can only be diagnosed in the absence of orthostatic hypotension 3, 1, 2

Pattern Recognition on Monitoring

During the test, expect to see:

• Heart rate and blood pressure both increase quickly at first, then gradually continue increasing over approximately 15 minutes 3
• No decrease in blood pressure (which would indicate orthostatic hypotension instead) 3
• The heart rate increase is sustained throughout the standing period 3

When to Consider Specialized Autonomic Testing

If the diagnosis remains unclear after stand test and tilt-table testing, refer to a specialist trained in autonomic function testing. 3

Autonomic function assessment should be performed in a dedicated laboratory and may include a battery of tests to characterize cardiovascular sympathetic and parasympathetic function. 3 No single autonomic function test provides comprehensive assessment, so different clinical questions require different test combinations. 3