Hello,
My mother had an operation of thyroid gland in 2005 and later doctors found cancerous cells there. So, the thyroid gland was removed from her body. Doctors medicated her 4 Oroxine (50 micrograms) tablets per day. She has been taking 4 oroxine from then to now on. But, yesterday she went to check up her TSH level and found that it is <1 uIU/ml. where the normal range starts from 4 uIU/ml. Now, what should she do? Will she have to stop taking the tablets to increase her TSH level?

We can advise or diagnose on the internet. This is a discussion you must have with her doctor, who knows her condition and has accessible medical records.