You can have an overactive thyroid gland where too much thyroid hormone is produced Hyperthyroidism. You can also have an underactive thyroid gland in which too little thyroid hormone is produced Hypothyroidism.
An example of this is Hashimoto's thyroiditis. The thyroid gland takes its direction from both the hypothalamus which is in your brain and the pituitary gland, a pea-sized gland at the base of your skull. In a complex dance, the hypothalamus releases something called thyrotropin-releasing hormone, which then triggers the pituitary gland to produce something called the thyroid stimulating hormone TSH.
Without TSH, the system would fail. Thyroxine T4 is responsible for your metabolism, mood, and body temperature, among other things. T3, too, is made in the thyroid gland, and it can also be made in other tissues within the body by converting T4 in a process called deiodination into T3.
This hormone is at the center of your digestive and metabolic function, and it also oversees bone health. When you specifically have too much T3, you might experience thyrotoxicosis, a condition that comes from an overactive thyroid gland, or hyperthyroidism. For example, an elevated free T4 —along with a low TSH — could indicate hyperthyroidism. As mentioned above, the thyroid stimulating hormone aka thyrotropin or thyrotrophin is produced by the pituitary gland.
It works sort of like the master of the hormones, and rules the production of T3 and T4 from its control center. If your TSH levels are too low, it may mean that your thyroid gland is making too much thyroid hormone. This excessive thyroid production could actually suppress the TSH.
But if you are concerned about thyroid issues, or if your hormones are imbalanced, your doctor may provide an initial TSH level blood test. This is because the TSH level can serve as a tip-off to other, more specific issues. Rice says. So, if your results are somewhere between 0. However, there is research that suggests that the reference range for TSH should be narrowed to 0.
Free T4, which tests for the amount of T4 that is available in the body, should range between 0. Furthermore, you may need a thyroid ultrasound or biopsy to determine the exact cause of your symptoms or hormone level imbalance.
There are several different thyroid disorders — all with their own root causes. Your endocrinologist or thyroid specialist will know what to test for, as there are many different tests per your specific condition and levels. Now that you have a basic overview of thyroid function, you may be wondering if there are ways to support your thyroid health — in addition to medication.
This is important because sometimes it can take a while before medication can correct hormone imbalance. In this case, the next best thing you can do is adjust your lifestyle habits.
When you are chronically stressed, adrenal fatigue — an overtaxing of the adrenal system — may kick in, triggering your body to release hormones as a way of coping. Measuring levels of thyroid antibodies may help diagnose the cause of the thyroid problem. While detecting antibodies is helpful in the initial diagnosis of hypothyroidism due to autoimmune thyroiditis, following their levels over time is not helpful in detecting the development of hypothyroidism or response to therapy.
TSH and FT4 are what tell us about the actual thyroid function or levels. A different antibody that may be positive in a patient with hyperthyroidism is the stimulatory TSH receptor antibody TSI. It is not a measure of thyroid function and it does not diagnose thyroid cancer when the thyroid gland is still present. It is used most often in patients who have had surgery for thyroid cancer in order to monitor them after treatment.
Tg is included in this brochure of thyroid function tests to communicate that, although measured frequently in certain scenarios and individuals, Tg is not a primary measure of thyroid hormone function. The thyroid has developed a very active mechanism for doing this. Therefore, this activity can be measured by having an individual swallow a small amount of iodine, which is radioactive.
The radioactivity allows the doctor to track where the iodine goes. By measuring the amount of radioactivity that is taken up by the thyroid gland radioactive iodine uptake, RAIU , doctors may determine whether the gland is functioning normally. A very high RAIU is seen in individuals whose thyroid gland is overactive hyperthyroidism , while a low RAIU is seen when the thyroid gland is underactive hypothyroidism.
In addition to the radioactive iodine uptake, a thyroid scan may be obtained, which shows a picture of the thyroid gland and reveals what parts of the thyroid have taken up the iodine see Thyroid Nodules brochure. There are many medications that can affect thyroid function testing. Some common examples include:. For information on thyroid patient support organizations, please visit the Patient Support Links section on the ATA website at www. Thyroid Function Tests. TESTS Blood tests to measure these hormones are readily available and widely used, but not all are useful in all situations.
Some common examples include: Estrogens , such as in birth control pills, or in pregnancy, cause high levels of total T4 and T3. It doesn't meet the standard definition of overt hypothyroidism. You may have no symptoms, and your thyroid function blood tests show a mixed picture.
Your free T4 level is normal, meaning your body is getting enough thyroid hormone. It is your TSH thyroid stimulating hormone level that is above the normal range, which indicates your thyroid gland has to work harder to pump out that thyroid hormone. One worry about mild hypothyroidism is the potential link between untreated subclinical hypothyroidism and coronary artery disease.
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