I suffered from hyperthyroidism myself and had to have ablation (i.e. the doctor gave me the radioiodine pill to kill off the thyroid). In my case, however, a small part of the thyroid has continued to work. So, I have to take thyroxine -- very small doses of it -- 0.05mg four times a week and 0.075 mg three times a week. My years of going to the endocrinologist tell me that it is a matter of trial and error until one can stay in the normal range. When my thyroid level was high, I felt anxious, wired and lost weight very quickly. If the thyroid level is low (which I have not experienced too much of), one tends to feel tired in the late afternoon and one puts on weight. Low thyroid levels can also impact one's cholesterol level.

Davidcpa, I know I have not really answered your question, but adjusting the dosage when needed is how my doctor has dealt with it. The level does seem to fluctuate.