I started 75 mcg of Synthroid 3 months ago. Therapeutic range according to this clinic is .8 - 1.7 My initial lab level was .7 and a myriad of symptoms. Thus, he started me on 75. I felt great within the first days, better than I have in 10 years - at least. 3 months later, symptoms were coming back to a lesser extent. Lab level increased from .7 to .8 Doctor wasn't going to increase as level was in therapeutic range. After some explaining to him, he increased dose to 100. I once again feel awesome, and again within a day, symptom free. My questions are: can I expect a slow return of symptoms? is it possible the initial (almost immediate) reduction in symptoms is related to the synthroid, or is it a placebo effect, and I also receive 300 mg of testosterone replacement therapy, how or is there a connection with these two hormones?