Test results are multinodular goiter so radionuclide thyroid scan?

Need more info: Not sure what you mean by "test results" but u cannot know that u have multinodular goiter from a blood test. A thyroid ultrasound can give u this diagnosis in which case u will need a blood test called TSH to know what to do next. No thyroid scan needed unless the TSH is low. Thyroid ultrasound vs. Biopsy might be needed depends on the size and characteristics of the nodules but need more info.

Not necessarily: Normal your doctor will just follow you unless he/she feels one dominant nodule. Then ultrasound and or nuclear scan of value.

Not necessarily: Multinodular goiter (mng) is enlargement of thyroid gland with multiple cysts and nodules. Sometimes diagnosed by physician on physical exam or patient complaining of neck mass. Non toxic (mng) do not produce excess thyroid hormone. Toxic mng proudce excessive hormone with sxs of hyperthyroidism. Ultrasound can define types of nodules. Sometimes if nodule larger than expected us guided biopsy.