I was told last Wednesday to stop taking Levothyroxin for four weeks so that I could have a radioactive scan of some nodules that I have in my thyroid gland.  My TSH levels have been dropping over the past six months and I am now hyperthyroid. The doctor suspects that one of my nodules might have gone toxic and is overproducing thyroid hormone.  I've been off Levothyroxin for five days now and am growing weaker and more shaky every day.  Has anyone else been told to be off thyroid medication for four full weeks before a scan?  Is there any supplement that I can take to give me some energy so that I can perform my daily functions?  I'd appreciate any advice out there.