What is the protocol for performing a standing test to diagnose Postural Orthostatic Tachycardia Syndrome (POTS)?

Standing Test Protocol for POTS Diagnosis

To diagnose POTS, measure blood pressure and heart rate after 5 minutes of lying supine, then have the patient actively stand and continue measurements at 1,3,5, and 10 minutes, looking for a sustained heart rate increase of ≥30 bpm (or ≥40 bpm in ages 12-19) or heart rate >120 bpm within 10 minutes, WITHOUT orthostatic hypotension (systolic BP drop ≥20 mmHg or diastolic BP drop ≥10 mmHg). 1, 2

Step-by-Step Testing Protocol

Pre-Test Preparation

• Patient should be fasted for 4 hours prior to testing 1
• Have patient lie supine for 5 minutes to establish baseline 2
• Measure baseline blood pressure and heart rate in the supine position 2

Active Standing Procedure

• Instruct the patient to stand up actively (not passively tilted) 3
• Active standing is superior to tilt testing for POTS diagnosis because it produces more consistent heart rate increases and better discriminates POTS from normal responses 4, 3
• Measure blood pressure and heart rate at the following time points:
  • 1 minute after standing 2
  • 3 minutes after standing 2
  • 5 minutes after standing 4
  • 10 minutes after standing 1, 2

Diagnostic Criteria (Must Meet ALL Three)

1. Heart Rate Criteria:

   • Heart rate increase ≥30 bpm from baseline within 10 minutes of standing 1, 2
   • OR heart rate >120 bpm absolute value 1, 2
   • For patients aged 12-19 years: heart rate increase ≥40 bpm 1, 2

2. Blood Pressure Criteria (Exclusion):

   • Must NOT have orthostatic hypotension (systolic BP drop ≥20 mmHg or diastolic BP drop ≥10 mmHg) 1, 2
   • This distinguishes POTS from other forms of orthostatic intolerance 2, 5

3. Symptom Criteria:

   • Frequent symptoms occurring with standing such as lightheadedness, palpitations, tremulousness, generalized weakness, blurred vision, exercise intolerance, and fatigue 1
   • Symptoms must be present for at least 6 months 6

Measurement Techniques

Equipment Options

• Standard sphygmomanometer is adequate for routine clinical testing due to ubiquity and simplicity 1
• Continuous beat-to-beat non-invasive BP measurement is helpful when more frequent values are required or in cases of doubt 1, 2
• Avoid automatic arm-cuff devices as they may be disadvantageous due to programmed repeat measurements when discrepant values occur 1

Critical Timing Considerations

The optimal time point for diagnosis matters: At 10 minutes of standing, the optimal heart rate increase cut-point is 29 bpm (not 30 bpm), with sensitivity of 87% and specificity of 67% 4. However, the traditional 30 bpm criterion at 10 minutes maintains high sensitivity (87-93%) 4.

Avoid using 30-minute protocols: If testing extends to 30 minutes, the 30 bpm criterion becomes inadequate—the optimal cut-point increases to 34 bpm for standing and 47 bpm for tilt testing 4.

Common Pitfalls to Avoid

• Do not rely solely on tachycardia: POTS diagnosis requires both orthostatic tachycardia AND orthostatic intolerance symptoms 4
• Do not use tilt table testing as first-line: Active standing produces more POTS-typical heart rate increases and more consistent results than passive tilt 4, 3
• Do not diagnose if orthostatic hypotension is present: The presence of a systolic BP drop ≥20 mmHg or diastolic BP drop ≥10 mmHg excludes POTS and suggests classical orthostatic hypotension instead 1, 2, 5
• Do not stop measurements too early: Heart rate increase must be assessed within the full 10-minute window, as some patients may not reach diagnostic criteria until later time points 1, 2

Alternative Testing: Tilt Table

If active standing is inconclusive or the patient cannot stand safely, head-up tilt testing at ≥60 degrees can be used 1, 2. However, tilt testing has lower specificity (40% at 10 minutes, 20% at 30 minutes) compared to active standing (67% at 10 minutes, 53% at 30 minutes) 4.