Levoxyl I have had a total thyroidectomy due to thyroid carcinoma about 2.5 -3 years ago. I have been on synthroid and levoxyl and both have caused tingling and numbness in my hands and feet, what I call a general fog (hard to concentrate or think, sometimes talk). I have been tested for neuropathy since endo said radiation may have caused issues. Only to be cleared by neurologist. Now endo switched does lower after rebout of cancer from 300mcg to 274mcg and have knee joints now going numb I want to sleep all the time, general weakness and now low testosterone levels.