i was first diagnosed with hashimoto's hypothyroidism back in 1993 and have been taking hormone replacement ever since. once you've been on the meds for several weeks, your doc will want to recheck your TSH (this is the most relevant marker, since it indicates how hard your thyroid is working to maintain appropriate T3 and T4 levels). the "normal range" of TSH is somewhat broad, and it has generally settled down to lower levels than when i was first diagnosed. as an endurance athlete, you want your TSH toward the lower end of the range (e.g., 0.5-1.0), and should discuss this with your doc if you test out appreciably higher but within the normal range. of course, you don't want your TSH too low, since, among other things, it can adversely affect your bones. if you use the search function on LRC, you'll come upon some extensive discussions of hashimoto's. the good news is that it is an entirely nondebilitating condition, provided you have access to the meds, and they're generally inexpensive -- another plus. one thing to note: be sure to take the pill in the absence of calcium, which counteracts its uptake. most people take the synthetic thyroxin first thing in the morning, leaving an hour or more between taking it and ingesting foods, drinks, or supplements that contain calcium.