Whatever symptoms have brought you to your doctor — fatigue, weight gain or loss, cold sensitivity — he or she wants to test you for a thyroid problem. Good thing: Thyroid conditions can be serious and even lead to life-threatening complications, which is why it’s important to catch them early. These tests are key to getting a precise diagnosis, and thus the right treatment:
TSH test. This blood test is usually the first thyroid test you’ll have. It measures the levels of thyroid-stimulating hormone (TSH) in your blood. TSH is produced in the pituitary gland and helps regulate the thyroid hormones T3 and T4. High amounts of TSH indicate hypothyroidism (underactive thyroid), while low TSH levels indicate hyperthyroidism (overactive thyroid). If your TSH levels are normal, your thyroid is probably working just fine.
Free T4 test. Another blood test, the T4 test, often follows the TSH test and provides a more accurate diagnosis, especially if the TSH test indicates hypothyroidism. This test monitors the amount of the T4 thyroid hormone circulating freely in your blood. If your TSH levels are high and your free T4 levels are low, you probably have primary hypothyroidism, caused by a malfunctioning thyroid gland. If both your TSH and free T4 levels are low, you probably have secondary hypothyroidism, caused by a malfunctioning pituitary gland.
T3 test. This blood test often follows the TSH when the TSH test indicates hyperthyroidism. It helps determine the severity of your hyperthyroidism, so that the proper treatment can be used. Thyroid antibody test. A fourth kind of blood test, the thyroid antibody test, may be ordered when earlier thyroid blood tests indicate an abnormality. Thyroid antibodies can either stimulate your thyroid gland, leading to hyperthyroidism, or damage it, causing hypothyroidism. This test also helps to determine the cause of your thyroid condition.
Thyroid scan. This test checks the visual appearance of your thyroid. To begin this test, you will take a pill that contains radioactive iodine, which is absorbed in your thyroid gland, so the scan will show an image of your thyroid. This test is useful in the diagnosis of hyperthyroidism as well as other thyroid conditions, such as thyroid cancer and thyroid nodules.
After you’ve completed these thyroid tests, your doctor will be able to diagnose your thyroid problem and get you started on treatment. If it turns out that you have hypothyroidism, you’ll probably receive medications that provide the hormones that your thyroid isn’t producing properly. If you have hyperthyroidism, you’ll probably be given medications to shrink or repress your thyroid. Each course of treatment is usually highly effective, and you’re likely to see improvements in your symptoms very soon.
Looking for more information? Learn more about thyroid health.