How to diagnose Hashimoto's Disease ? 

Diagnosis begins with a physical exam and medical history. A goiter, nodules, or growths may be found during a physical exam, and symptoms may suggest hypothyroidism. Health care providers will then perform blood tests to confirm the diagnosis. A blood test involves drawing blood at a health care providers office or a commercial facility and sending the sample to a lab for analysis. Diagnostic blood tests may include the
                
- TSH test. The ultrasensitive TSH test is usually the first test performed. This test detects even tiny amounts of TSH in the blood and is the most accurate measure of thyroid activity available. Generally, a TSH reading above normal means a person has hypothyroidism.  - T4 test. The T4 test measures the actual amount of thyroid hormone circulating in the blood. In hypothyroidism, the level of T4 in the blood is lower than normal.  - antithyroid antibody test. This test looks for the presence of thyroid autoantibodies, or molecules produced by a persons body that mistakenly attack the bodys own tissues. Two principal types of antithyroid antibodies are      - anti-TG antibodies, which attack a protein in the thyroid called thyroglobulin    - anti-thyroperoxidase (TPO) antibodies, which attack an enzyme called thyroperoxidase in thyroid cells that helps convert T4 to T3. Having TPO autoantibodies in the blood means the bodys immune system attacked the thyroid tissue in the past. Most people with Hashimotos disease have these antibodies, although people whose hypothyroidism is caused by other conditions do not.
                
A health care provider may also order imaging tests, including an ultrasound or a computerized tomography (CT) scan.
                
- Ultrasound. Ultrasound uses a device, called a transducer, that bounces safe, painless sound waves off organs to create an image of their structure. A specially trained technician performs the procedure in a health care providers office, an outpatient center, or a hospital, and a radiologista doctor who specializes in medical imaginginterprets the images; a patient does not need anesthesia.
                
- The images can show the size and texture of the thyroid, as well as a pattern of typical autoimmune inflammation, helping the health care provider confirm Hashimotos disease. The images can also show nodules or growths within the gland that suggest a malignant tumor.
                
- CT scan. CT scans use a combination of x rays and computer technology to create images. For a CT scan, a health care provider may give the patient a solution to drink and an injection of a special dye, called contrast medium. CT scans require the patient to lie on a table that slides into a tunnel-shaped device where the x rays are taken. An x-ray technician performs the procedure in an outpatient center or a hospital, and a radiologist interprets the images. The patient does not need anesthesia. In some cases of Hashimotos disease, a CT scan is used to examine the placement and extent of a large goiter, and to show a goiters effect on nearby structures.
                
More information is provided in the NIDDK health topic, Thyroid Tests.