High Heart Rate + HRM?

BostonStrong617

Hello Forums Peoples,
I'm hoping to can help me out with a quick question.

I take a stimulate medication (Specifically Adderall) I've been on this 10 years, it's needed, I cannot focus of function without it. Days I don't take it are only weekends when I'm not working and don't have to get anything done but even that is rare. Obviously it raises my heart rate. My resting heart rate is normally about 60 BPM at rest. When I take my medication it shoots about to about 100 BPM or perhaps 110-115 if you add coffee into the mix.

Now I have an HRM that I use to calculate calories burned. Now I'm wondering if it over-estimates the amount of calories I burn when I run because my HR gets up to 180 due to already being at 100ish before I even begin cardio. I'm 5'4 and 120 pounds and normally burn anywhere from 100-150 calories per mile (So in about 8-9 minutes) depending on speed and elevation. Note although my HR is quite high I'm not feeling like I'm gasping for breath, in fact on my longer runs by the 5th mile or so my HR tends to settle comfortably in the 160's but even prior to that I don't feel I have to slow down to catch my breath often

I'm just curious as to weather or not having such a high HR due to a medication can actually cause an HRM to over-estimate how much you're burning due to exercise? I don't want to be over eating or under eating but often find I am hungry on run days so much so that "eat half back" doesn't always work.

To be safe I normally just subtract about 20 percent in my total but if anyone has any ideas or answers I'd really appreciate it!