Hi, I had a total thyroidectomy in 2012, with RAI and this past April had 40 lymph nodes removed, 7 of which were positive for papillary cancer recurrence. I just had my follow-up bloodwork and am on 125 Synthroid 8x/week. My Tg was 6.3, down from 23.7 and my TSH is 0.77. I was told that the Tg is still high, since it should be 0 and this means there still could be residual tumors although invisible on US. Why do I need to have lower than normal thyroid levels to suppress the tumor growth?