Researchers in Austria conducted a study involving 426 women aged 19 years or older who were undergoing surgery for benign thyroid disease (not on thyroid hormone replacement).
The number of reported symptoms was significantly higher among women with TPO antibody levels exceeding 121 IU/mL compared with women who had lower TPO antibody levels.
TPOab does not directly correlate with how we feel, i.e. someone with antibodies in the thousands can feel better than someone with them in the low hundreds. The effect of the antibodies seems to decrease oover time and with continued destruction of the thyroid. Once it's pretty well gone, and you're on full replacement hormones, it becomes much more stable.
"Would this mean the thyroid is still being attacked and would you still have symptoms?" Can you elaborate? I don't think I understand this part of your question.