How to Diagnose POTS
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, in the absence of orthostatic hypotension, accompanied by symptoms of orthostatic intolerance. 1, 2
Core Diagnostic Criteria
All three criteria must be present simultaneously:
- Heart rate increase: ≥30 bpm rise from supine to standing within 10 minutes (≥40 bpm for ages 12-19 years) 1, 2
- Standing heart rate: Often exceeds 120 bpm 1, 2
- Absence of orthostatic hypotension: No systolic BP drop ≥20 mmHg or diastolic BP drop ≥10 mmHg within 3 minutes of standing 1, 2, 3
- Symptoms of orthostatic intolerance: Must be present and include lightheadedness, palpitations, tremulousness, generalized weakness, blurred vision, exercise intolerance, and fatigue 1, 2
Diagnostic Testing Protocol
Active Stand Test (Preferred Initial Test)
Perform a 10-minute active stand test with continuous monitoring: 2
- Measure BP and heart rate after 5 minutes of lying supine 2
- Record immediately upon standing, then at 2,5, and 10 minutes after standing 2
- Patient must stand quietly for the full 10 minutes as heart rate increase may be delayed 2
- Document all symptoms occurring during the test 2
Testing Conditions (Critical for Accuracy)
Standardized conditions prevent false results: 2
- Perform in quiet environment with temperature 21-23°C 2
- Patient fasted for 3 hours before testing 2
- Avoid nicotine, caffeine, theine, or taurine-containing drinks on test day 2
- Ideally perform before noon 2
Tilt-Table Testing
Use tilt-table testing if active stand test is inconclusive but clinical suspicion remains high 2
Symptom Profile to Evaluate
Orthostatic symptoms (occur with standing, relieved by sitting/lying): 1, 2
- Lightheadedness and dizziness (most common, present in 97.6% of patients) 4
- Palpitations 1, 2
- Tremulousness 1
- Generalized weakness 1
- Blurred vision or tunnel vision 2
Non-postural symptoms: 1
- Bloating, nausea, diarrhea, abdominal pain 1
- Fatigue and lethargy 2
- Sleep disturbance 1
- Migraine headaches 1
- Cognitive difficulties ("brain fog") 2
- Chest pain 2
Initial Workup
Essential baseline testing: 2
- 12-lead ECG to rule out arrhythmias or conduction abnormalities 2
- Thyroid function tests to exclude hyperthyroidism 2
- Medication review, especially cardioactive drugs 2
- Detailed medical and family history 2
For pediatric patients (ages 12-19): 2
- Screen for joint hypermobility using Beighton score (≥6/9 points before puberty) 2
- Confirm symptoms present for at least 6 months 2
Critical Diagnostic Pitfalls
Failure to perform full 10-minute stand test: Heart rate increase may be delayed, and stopping early misses the diagnosis 2
Not excluding orthostatic hypotension: POTS can only be diagnosed when orthostatic hypotension is explicitly absent; approximately 51% of POTS patients also have initial orthostatic hypotension, which must be distinguished 3
Using wrong age-based criteria: In adolescents 12-19 years, using adult criteria (≥30 bpm) instead of pediatric criteria (≥40 bpm) leads to overdiagnosis 2
Not maintaining proper testing conditions: Failure to fast for 3 hours or avoid stimulants affects hemodynamic responses and leads to inaccurate results 2
Missing secondary causes: Dehydration, medications, diet, primary anxiety disorder, or eating disorders can mimic POTS and must be excluded 2
Confusing with other conditions: POTS must be distinguished from inappropriate sinus tachycardia, other tachyarrhythmias, and neurogenic orthostatic hypotension (which shows blunted HR increase <10 bpm) 2, 3
Associated Conditions to Consider
POTS frequently coexists with: 3