What does it mean when a sonogram report says that your thyroid was very prominent?

Thyroid is large: Most likely, you have hypothyroidism which is a very common condition. This information is used in conjunction with a "thyroid panel" or "thyroid studies". As long as there aren't any other findings like nodules or masses on the ultrasound, you should be ok. Good luck.

That its big: It just means that your thyroid is a little bigger than average. It says nothing about thyroid function, which can only be assessed through blood tests.