Sometimes, doctors will notice signs of thyroid cancer, such as a lump or swelling in your neck, during a routine checkup. If your doctor thinks you have thyroid cancer, he or she will ask you about your symptoms, health history, and family health history. This information helps your doctor determine your risk for thyroid cancer.
In addition to a physical exam, your doctor may perform certain tests to see if you have thyroid cancer. You may need more than one of these tests:
Neck exam. Your doctor will try to feel for any lumps near your thyroid. If your doctor finds a lump, he or she will check its size and firmness. Your doctor will also see if it moves or feels tender to you.
Ultrasound. During this test, sound waves are used to look for thyroid cancer. The sound waves bounce off your thyroid and send back signals. A computer uses the signals to create an image of your thyroid. The image can reveal the size and location of any thyroid nodules or bumps. However, this test alone cannot tell you if these nodules are cancerous.
Biopsy. After a thyroid ultrasound, your doctor will most likely want you to have a biopsy. During a biopsy, a specialist will use the ultrasound images to guide a very fine needle into your thyroid to check it for cancer. This procedure lets the doctor collect thyroid cells and surrounding fluid. Afterwards, an expert who looks for changes in cells, called a pathologist, will examine the cells and fluid under a microscope to see if there are any signs of cancer. A biopsy provides the information necessary for your doctor to diagnose thyroid cancer.
Blood tests. Your doctor may do a blood test to check certain hormone levels in your body. These levels tell your doctor if your thyroid is working properly. The hormones your doctor may check include thyroid-stimulating hormone and other hormones, including T3, T4, and calcitonin. Your doctor also may check for a protein called thyroglobulin. The results of these blood tests do not diagnose cancer, but they do give your doctor information on how well your thyroid gland is working.
Thyroid scan. Your doctor may order a scan of your thyroid. For this test, you swallow a small amount of a radioactive substance. Your doctor may also inject the substance into your vein, where it will travel through your bloodstream. Thyroid cells that absorb the radioactive substance are more likely to be cancerous; your doctor will see these cells on a scan that a special camera takes.