I never thought about this before, since my thyroid levels are checked several times a year, but a number of women write to me about thyroid issues and tell me they have been taking the same dose of thyroid medication for 5 years or more----without any additional testing being done by their healthcare practitioner. When I tell them that they need to have their levels checked if they are symptomatic, they often tell me their doctor doesn't see a need to test since they have "found the right dosage". I find that strange, as the body is dynamic, always changin, and thus, our medication/hormone needs change (thyroid is a hormone, by the way.)
Some good information in this article from the TorontoSun.com----and the emphasis is that if you are taking thyroid medication, you need regular monitoring by a health care professional (ideally one who knows what the hell he or she is doing in regards to thyroid treatment!). If you have not had your thyroid levels checked in the last year or more, be sure to ask about it at your next appointment!