Diagnosis

Your doctor may discover an enlarged thyroid gland simply by feeling your neck and having you swallow during a routine physical exam. In some cases, your doctor may also be able to feel the presence of nodules.

Diagnosing a goiter may also involve:

• A hormone test. Blood tests can determine the amount of hormones produced by your thyroid and pituitary glands. If your thyroid is underactive, the level of thyroid hormone will be low. At the same time, the level of thyroid-stimulating hormone (TSH) will be elevated because your pituitary gland tries to stimulate your thyroid gland to produce more thyroid hormone.

  A goiter associated with an overactive thyroid usually involves a high level of thyroid hormone in the blood and a lower than normal TSH level.

• An antibody test. Some causes of a goiter involve production of abnormal antibodies. A blood test may confirm the presence of these antibodies.
• Ultrasonography. A wand-like device (transducer) is held over your neck. Sound waves bounce through your neck and back, forming images on a computer screen. The images reveal the size of your thyroid gland and whether the gland contains nodules that your doctor may not have been able to feel.

• A thyroid scan. During a thyroid scan, a radioactive isotope is injected into the vein on the inside of your elbow. You lie on a table with your head stretched backward while a special camera produces an image of your thyroid on a computer screen.

  The time needed for the procedure may vary, depending on how long it takes the isotope to reach your thyroid gland. Thyroid scans provide information about the nature and size of your thyroid, but they're more invasive, time-consuming and expensive than ultrasound tests.

• A biopsy. During a fine-needle aspiration biopsy, ultrasound is used to guide a needle into your thyroid to obtain a tissue or fluid sample for testing.