A biopsy helps your doctor find the cause of a nodule or goiter. But you don’t need it for all thyroid problems.
Your doctor will likely want to check on any nodule bigger than about 1 centimeter (about half an inch), especially if imaging shows that the nodule is solid, has calcium on it, and doesn’t have clear borders around it.
You might also get a biopsy without a nodule if you’re in a lot of pain and your thyroid is growing quickly.