Congrats on getting in to western states!
I'm not sure I understand all of your post - did you have a partial thyroidectomy last November? Normal TSH levels after that, but now your TSH is 8.5?
Life is not measured by the number of breaths we take, but by the number of moments that take our breath away...(unkown) • Go With The Flow • Thyroid Support Group
Wow - the Western States 100 - I'm totally impressed. Sounds like you have plenty of energy; though I would be dragging my A$$ at 8.5! What is the name of the medication your doctor is suggesting?
Go as long as you can, and then take another step.
I did a little searching and found this page about hypothyroidism and endurance athletes
Interesting that they mention the connection between adequate caloric consumption and endurance exercise. I knew that people who are anorexic often have problems with hypothyroidism - the body's attempt to slow metabolism in the face of starvation. Not saying that is your problem, but I wonder if that contributed to my problems when I intentionally dropped 5 lbs while marathon training a couple of years ago.
I don't know what to tell you about starting meds before your race - you are the only one who knows how much you think this is affecting you - did the high TSH show up as part of a routine check or did feeling off prompt the lab work? Part of the problem is that you might only feel a little bad now, but if your thyroid cotinues to struggle, in five weeks, you might be feeling worse. In your situation with the race, becoming hyperthyroid might be more of problem them being a little hypo - but if you were to start on a low dose of thyroid replacement, you would probably know within 2 weeks if it was too high a dose or not, that would still give you time to reduce the dose or stop until after the race.
Please keep us posted on how things turn out for you, and best of luck on your race.