I had my thyroid gland removed 44 years ago,never took meds,do I have to start taking them now?

I am 77 years old,I had my thyroid gland totally removed.I was never put on any meds.I recently had tia’s and the doctor now says that I should take Synthroid.I have never had any symptoms of hypo or hyper.I can not afford to go get blood tests and scans
every 3 mos.