If i've had a total thyroidectomy, how long can i survive without taking my thyroid replacement medicine. i'm 37.

Depends: The thyroid hormone will decrease over time and then your metabolism will slow affect every organ in your body including your heart,you will get more fatigued over weeks to months.Missing a dose for a few days to week probably will not notice much but your body would.Eventually it will lead to more serious health problems but varies by individual.Not a good idea to do.