I remember having the same fears. Most doctors understand that if your heart rate goes up by 30 bpm’s within 10 minutes, it’s POTS—OR if it goes above 120 bpm’s—but you don’t need to meet both criteria. Honestly, you are right—results can vary fairly widely. How can we say that if it goes up 29 bpm’s that it is not POTS? Clearly, some common sense is called for, right? If you are having large swings with the poor man’s TT, I’ll betcha’ my Gatorade that your heart rate will jump significantly on a regular TTT. Let us know?