Hi all - I've been on thyroid meds for 12 years, had thyroid cancer and now have no thryoid and no parathyroids (they produce most of your calcium).
Here are some important facts I've "discovered" over the years...you must take your meds on an empty stomach; grapefruit and calcium interfere with the absorption of thyroid meds - don't eat too much grapefruit, and take calcium at least an hour after your synthroid; generics are NOT the same - w/thyroid meds, such a small change has such a big impact! (I changed from generic to name-brand and cut my dose in half!); it truly does take 6 weeks to see a difference - your body stores the meds in your body and releases it for use little by little until enought is stored; people on thryoid meds (or me at least) get more wiped out than most by illnesses - we don't have a metabolism that can adjust and "kick it up" when we need it! Like someone else said, your levels change throughout your life - get checked by an endo, they seem able to "fine tune" it more.
Also, a previous poster mentioned about going off her meds for a test...my experience with that has been, as she stated, for an uptake, where they test with radioactive iodine to see how much is taken up into the thyroid cells. This is how I've been tested for the cancer. Going off the meds for 6 weeks was the worst!! Now they have a new procedure that I've had done the last few years where you get injections, so you don't have to go off your meds. Encouraging news!!
Hope this helps!!