Thyroid ultrasound = no concern ; thy. antibody test showed no autoimmune cause. tsh still high, even on synthroid. ft4 high end of normal. causes???

Two thoughts: 1. This sounds like primary thyroid failure ("simple" HYPO-thyroidism) which is "borderline" but is causing the high TSH (Think of the TSH "trying" to "waken" the "sleeping" gland. 2. Synthroid per se (=thyroxine (T-4) is a POOR TSH suppressant ...it needs to be converted to T-3 to suppress the TSH..thus a SWITCH in your thyroid pills to a T-3 may help! Hope this is helpful Dr Z