I was initially diagnosed with overactive thyroid and put on medication. I was on and off it for years, but my thyroid was gradually enlarging. My GP referred me to endocrinologist but after 3 years waiting (I’m in Ireland), I finally went to him privately. He referred me for various tests, including biopsy of nodules that could be felt. But he didn’t recommend surgery. Meanwhile, appointment with surgeon came up (separately referred by GP). Surgeon could feel nodules and said surgery was essential as otherwise pressure of enlarged thyroid could strangle me!
It was only when I had CT scan prior to surgery that thyroid was measured as much bigger than it appeared, as it had grown down into upper chest.
Interestedly, neither GP nor endocrinologist had recognized the problems thyroid was causing, despite my complaining of intermittent pain and difficulties swallowing.