🧠 The 5-1-3-20 Protocol

5 = 5 minutes supine before baseline (allows cardiovascular equilibrium)
1 = Measure at 1 minute standing (catches immediate OH)
3 = Measure at 3 minutes standing (catches classic/delayed OH)
20 = ≥20 mmHg systolic drop = positive result

Mnemonic: "5 down, 1 up, 3 standing, 20 is the drop"

For hypertensive patients: >30 mmHg systolic is significant. (ACC/AHA 2017)