Tests and diagnosis

By Mayo Clinic Staff

A diagnosis of Graves' disease is based primarily on your answers to the doctor's questions and findings from a physical exam. He or she may also order laboratory tests to confirm a diagnosis or gather more evidence if a diagnosis isn't clear. Diagnostic procedures may include:

  • Physical exam. Your doctor examines your eyes to see if they're irritated or protruding and looks to see if your thyroid gland is enlarged. Because Graves' disease increases your metabolism, your doctor will check your pulse and blood pressure and look for signs of tremor.
  • Blood sample. Your doctor may order blood tests to determine your levels of thyroid-stimulating hormone (TSH), the pituitary hormone that normally stimulates the thyroid gland, as well as levels of thyroid hormones. People with Graves' disease usually have lower than normal levels of TSH and higher levels of thyroid hormones. Another laboratory test measures the levels of the antibody known to cause Graves' disease. This test usually isn't necessary to make a diagnosis, but a negative result might indicate another cause for hyperthyroidism.
  • Radioactive iodine uptake. Your body needs iodine to make thyroid hormones. By giving you a small amount of radioactive iodine and later measuring the amount of it in your thyroid gland with a specialized scanning camera, your doctor can determine the rate at which your thyroid gland takes up iodine. A high uptake of radioactive iodine indicates your thyroid gland is overproducing hormones.
  • Imaging tests. If the diagnosis of Graves' ophthalmopathy isn't clear from a clinical assessment, your doctor may order an imaging test, such as computerized tomography (CT), a specialized X-ray technology that produces thin cross-sectional images. Magnetic resonance imaging (MRI), which uses magnetic fields and radio waves to create either cross-sectional or 3-D images, may also be used.
Jul. 07, 2011