The thyroid is a small gland located in the neck. It is responsible for producing hormones, mainly tri-iodothyronine (T3) and thyroxine (T4). These hormones play a role in regulating metabolism and body temperature. The activity of the thyroid gland is controlled by the pituitary gland. This gland, located in the brain, monitors how much T3 and T4 are available. If the levels get too low the pituitary secretes a thyroid-stimulating hormone, or TSH. This signals the thyroid gland to make more. Once the level of thyroid hormones gets high, then the thyroid gland is signaled to stop its production. If the thyroid gland is chronically under-active or overactive you can develop many symptoms. If you think your thyroid gland is not working properly, your doctor can run tests to diagnose a thyroid problem.
Physical Exam
Your doctor will need to perform a physical which will include asking you about your symptoms. If the thyroid gland is over-active (hyperthyroidism) he will look for signs of increased metabolic activity. The Hormone Foundation states that this includes unexplained weight loss, muscle tremors, chronic diarrhea, rapid pulse, irritability, fatigue and infertility. If your thyroid gland is underactive (hypothyroidism) you may exhibit weight gain, fatigue, depression, dry and brittle skin, hair and nails, constipation and a lack of energy. In addition, your physician will check your neck for thyroid nodules or small growths on the thyroid gland, signs of swelling in the neck area and/or a goiter, which is an enlargement of the thyroid gland.
Blood Tests
There are several simple blood tests your doctor can do to determine how well your thyroid gland is working. According to the American Thyroid Association, the most common test is a TSH test. Since the pituitary gland releases TSH if it senses low levels of thyroid hormone, a high reading on a TSH test signals hypothyroidism. In contrast, a low TSH reading signals that the thyroid gland is overactive and producing too much. A normal TSH level is 0.4 to 4.0 mIU/L. Blood tests can also detect the levels of T4 and T3. If you have hyperthyroidism then your levels of both of these will be elevated. If you have hypothyroidism then the levels will be low. A normal T4 value is 4.5 to 11.2 mcg/dL. A normal T3 level is 100 to 200 ng/dL.
Radioactive Iodine Uptake Test
Also known as RAIU or thyroid uptake test, this scan involves injecting a dye into your system and using imaging tests to follow the dye. The dye is a radioactive material that can be picked up on an x-ray or special camera. The dye will accumulate around the thyroid gland. The x-ray, camera or scan that is used will show pictures of your thyroid gland. The American College of Radiology states that this test will allow your doctor to see the size and shape of your thyroid gland and will detect abnormalities in structure or function.
Thyroid Antibody Test
The American Association for Clinical Chemistry suggests that your doctor may run a thyroid antibody test, if other thyroid tests come back positive and more information is needed. It will help to determine if your thyroid condition is caused by an autoimmune disease. In some cases a thyroid disorder is a complication of another condition. If you have an autoimmune condition it means that your immune system is more active than normal. It is mistaking the body for a foreign invader and initiating an attack by releasing antibodies. In the case of thyroid problems, if you have an autoimmune disease causing your condition, then this test would detect the presence of thyroid antibodies.
