The question was: Will it change my medication dosage? Will I "use up" my medication?
That depends on how your pituitary gland/and or thyroid gland are working these days. For example, if you have Hashimoto's thyroiditis, you might experience fluctuations in your thyroid hormone levels frequently, necessitating dose changes. If your thyroid function (and pituitary function) are stable, you might not be needing to change doses.
I did an experiment myself, I kept close tabs on my thyroid function for the past 2 years with the help of my doctor. I was in the process of training for a double Badwater run, and I was wondering the same thing myself. Normally I'm a 50ish mile a week runner. For my Badwater double, I was running 120 mile weeks. I also ran two other long ultras in the 7 months leading up to Badwater, of 114 and 151 miles. In the year before that I ran several 100 milers and multiple long training runs up to 70 miles.
During the entire 19 month period of time my thyroid function and medication dose did not fluctuate at all, except when I intentionally played with the medication. Here's what I did: I knew that being hyperthyroid in the heat of Death Valley in the summer would not be good. I have always felt at my best with a TSH of around 1. At the beginning of my training my TSH was 0.6. I felt this might be too much on the hyperthyroid end of things for what I was expecting of my body.
I did an experiment, and I told my doctor what I was doing. I skipped my Levoxyl (also known as levothyroxine/Synthroid/T4) once a week for 3 months, then re-tested. My TSH went up to 2.4. I added the missing Levoxyl back twice a month, so that I was only skipping my Levoxyl every other week- I did it on alternating Tuesdays, the same days that we have our recyclables picked up, which helped me remember. After 3 months on this, I tested again, in May, two months before the race, which would give me time to make any necessary adjustments.
My TSH was exactly 1.0. Pretty good, huh?
I went to Badwater, got a PR in the race, successfully did my double crossing, with no problems at all.
And three months later, as of today, I have taken an 8 week break from running, cut my total exercise and workout time to about one-third of what I was doing over the past two years, and I still skip the every other week dose of Levoxyl. I can't tell that anything has changed, except so far I've lost 4 pounds. I have a feeling it has more to do with being less exhausted from training than it does with my thyroid. I'll follow up with more on this soon.I'm going for my annual physical exam in a few weeks and will get my labs drawn again, so I'll let you know.
That's my experiment. Don't try this at home without discussing it first with the same doctor who prescribes the medication.
