The treatment of hypothyroidism means striking a careful balance between a patient's symptoms and the lab (usually TSH) value. TSH is the most relied upon lab by thyroid experts world-wide to determine appropriate levels of thyroid hormone replacement. It does not directly reflect tissue activity of thyroid hormone but there is no test available that does that and TSH is the best approximate we have now.
That being said, the target TSH is 0.5-2.0 for a patient on replacement. In general, patients who are older or have heart disease do better with a TSH that is not <0.5 as shown in several studies that these patients have increased risk of premature death.
The celiac sprue (gluten sensitivity) likely decreases the synthroid absorption -- explaining your high dose requirements. Changing to levoxyl may be worthwhile as some patients are sensitive to the fillers in one med but not the other - in terms of thyroid hormone they contain the exact same thyroid hormone. Don't know if it will effect the memory problems but worth a try -- and remember the TSH goal.
i wish i could give you some advice, im just learning about all this myself, but reading your storie made me feel for you. how fustrating you must feel. i hope you get some one to help you or some dr to give you something diffrent. my son has 0 blood too, i hope he dosn't have any problems. hell start meddican on monday for the first time