After completing a POTS Check test, you'll receive detailed data about how your body responded to standing. This page explains what each metric means and how to interpret your results for discussions with your healthcare provider.
The Key Metric: Heart Rate Change (ΔHR)
The most important number in your results is the heart rate change, shown as ΔHR (delta HR). This is calculated as:
ΔHR = Maximum Standing HR - Baseline HR
Baseline HR is calculated from the mean of your heart rate during the final 2 minutes of the lying-down phase, when your body is most relaxed.
Maximum Standing HR is the highest 30-second rolling average during the standing phase, representing the peak of your body's response.
Age-Based POTS Thresholds
POTS Check uses age-appropriate thresholds based on medical research showing that younger people naturally have higher heart rate variability:
Ages 13-19 (Pediatric)
ΔHR ≥ 40 bpm
A heart rate increase of 40 or more beats per minute when standing may indicate a POTS-consistent response in adolescents.
Ages 20+ (Adult)
ΔHR ≥ 30 bpm
A heart rate increase of 30 or more beats per minute when standing may indicate a POTS-consistent response in adults.
Why Different Thresholds?
Research has shown that healthy adolescents often have naturally higher heart rate responses to standing than adults. Using a 40 bpm threshold for ages 13-19 helps avoid false positives while still identifying potentially concerning patterns.
Understanding Your Result Categories
Normal Response
Your heart rate increase is below the threshold for your age group. This suggests your autonomic nervous system is responding normally to the postural change.
Note: A "normal" result doesn't rule out POTS or other conditions. Symptoms, daily variability, and other factors matter. If you have concerning symptoms, discuss them with your healthcare provider regardless of test results.
POTS-Consistent Response
Your heart rate increase meets or exceeds the threshold for your age group. This pattern is consistent with POTS criteria and warrants discussion with a healthcare provider.
Important: This is NOT a diagnosis. Only a qualified healthcare provider can diagnose POTS after a comprehensive evaluation that includes medical history, physical examination, and possibly additional testing.
Additional Metrics
Posture Quality Score
POTS Check uses your iPhone's motion sensors to assess how still you remained during the test. Better posture quality means more reliable results.
- A (Excellent): >90% stable posture, <5% movement artifacts
- B (Good): 70-90% stable, 5-15% artifacts
- C (Fair): 50-70% stable, 15-30% artifacts
- D (Poor): <50% stable or >30% artifacts — results may be unreliable
Blood Pressure Changes (Optional)
If you manually enter blood pressure readings, POTS Check can identify additional patterns:
- Orthostatic Hypotension (OH): Systolic drop ≥20 mmHg or diastolic drop ≥10 mmHg
- Orthostatic Hypertension (OHT): Systolic increase ≥20 mmHg or diastolic increase ≥10 mmHg
Blood pressure patterns can help differentiate between different types of orthostatic dysfunction and provide additional context for your healthcare provider.
Symptom Log
If you logged symptoms during the test using the button on your Apple Watch, these timestamps are included in your results. Correlating symptoms with heart rate changes provides valuable information about your autonomic response.
What Your Results Don't Tell You
Limitations of Home Screening
- Results do NOT diagnose POTS or any other medical condition
- Apple Watch heart rate data is an approximation, not medical-grade
- A single test doesn't capture day-to-day variability
- Many factors affect results (hydration, caffeine, stress, medications)
- Normal results don't rule out POTS if you have symptoms
Talking to Your Doctor
POTS Check generates PDF reports specifically designed for sharing with healthcare providers. Your report includes:
- Test date, time, and duration
- Baseline and standing heart rate data
- Calculated ΔHR with age-based interpretation
- Blood pressure readings (if entered)
- Symptom timestamps and notes
- Posture quality score
- Health Profile data (if imported, Secure Account only)
When discussing your results, explain that you used the NASA Lean Test protocol — many healthcare providers are familiar with this screening approach.
Tracking Over Time
With a Secure Account (free), you can take multiple tests and track trends over time. This is valuable because:
- POTS symptoms fluctuate: You might feel worse on some days than others
- Identify triggers: Correlate results with sleep, diet, hydration, or activities
- Monitor treatments: Track whether interventions are helping
- Provide better data: Multiple tests give your doctor a more complete picture