I Have Been Diagnosed With Hashimotos Following A Full Thyroid

I have been diagnosed with Hashimotos following a full thyroid blood test with excessive antibody counts and a subsequent scan showing thyroid nodules. Bloods have been improving until last week, when I was called by my GP to have a re-blood test due to my eutrophic count being 0.8 - what is the realistic and most likely reason for this?