First investigation test for enlarged thyroid is ultrasound. For additional investigation, Fine Needle Aspiration (FNA) can also be conducted. Ultrasound is used for the evaluation of enlarged, bumpy and/or nodular thyroid gland. The ultrasound waves generate images of thyroid gland resting inside your neck. Since naked eye can’t see the parameters of thyroid gland therefore when the physician feels increase in the size of thyroid they order an ultrasound. The images clearly show any lumps, nodules or enlargement. Fine Needle Aspiration (FNA) Biopsy is a procedure in which a needle is injected into the thyroid gland to take out a sample of thyroid tissue or fluid. This test is used to rule out cancer.