Diagnosing Thyroid Cancer

If you have symptoms that suggest thyroid cancer, your doctor will help you find out whether they are from cancer or some other cause. Your doctor will ask you about your personal and family medical history. You may have one or more of the following tests:

  • Physical exam: To feel your thyroid for lumps (nodules). Your doctor also checks your neck and nearby lymph nodes for growths or swelling.
  • Blood tests: To check for abnormal levels of thyroid-stimulating hormone (TSH) in the blood. Too much or too little TSH means the thyroid is not working well. If your doctor thinks you may have medullary thyroid cancer, you may be checked for a high level of calcitonin and have other blood tests.
  • Ultrasound: To create a picture and learn the size and shape of each nodule and whether the nodules are solid or filled with fluid. An ultrasound device uses sound waves undetected by people. The device aims sound waves at the thyroid, and a computer creates a picture of the waves that bounce off the thyroid. The picture can show thyroid nodules that are too small to be felt. Nodules that are filled with fluid are usually not cancer. Nodules that are solid may be cancer.
  • Thyroid scan: To view thyroid cells. You swallow a small amount of a radioactive substance, and it travels through the bloodstream. Thyroid cells that absorb the radioactive substance can be seen on a scan. Nodules that take up more of the substance than the thyroid tissue around them are called hot nodules. Hot nodules are usually not cancer. Nodules that take up less substance than the thyroid tissue around them are called cold nodules. Cold nodules may be cancer.
  • Biopsy: To take a sample of tissue that can be viewed under a microscope. A biopsy is the only sure way to diagnose thyroid cancer.

Your doctor may take tissue for a biopsy in one of two ways:

  • Fine-needle aspiration: Most people have this type of biopsy. Your doctor removes a sample of tissue from a thyroid nodule with a thin needle. An ultrasound device can help your doctor see where to place the needle.
  • Surgical biopsy: If a diagnosis cannot be made from fine-needle aspiration, a surgeon removes the whole nodule during an operation. If the doctor suspects follicular thyroid cancer, surgical biopsy may be needed for diagnosis.
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