Thyroid panel tests are used to determine the levels of T3 and T4 hormones in your blood. Low amounts of these hormones indicate an underactive thyroid gland (hypothyroidism), where excessive levels of T3 and T4 indicate an overactive thyroid (hyperthyroidism).
Detecting an under or overactive thyroid can help doctors diagnose thyroid-related disorders such as:
- Thyroid cancer
- Goiter: An enlargement of the thyroid gland which can cause pain, hoarseness, swelling, and dizziness.
- Hashimoto’s disease: An autoimmune disorder that attacks cells in the thyroid gland, resulting in hypothyroidism.
- Thyroiditis: Inflammation of the thyroid, which can result in hypothyroidism or hyperthyroidism.
- Grave’s disease: An autoimmune disorder that results in hyperthyroidism.
The thyroid gland produces the hormones triiodothyronine (T3) and thyroxine (T4), which help regulate metabolism. Metabolism can affect your weight, body temperature, and energy. An under or overactive thyroid can alter your heart rhythms, which may lead to heart failure.
Hypothyroidism: An underactive thyroid gland slows down the metabolism, which can lead to weight gain and fatigue. Other symptoms of hypothyroidism include:
Hypothyroidism is commonly caused by Hashimoto’s disease, an autoimmune disease in which cells in the thyroid are mistakenly attacked by your body’s immune system. An underactive thyroid can lead to heart problems, mental health problems, nerve damage, infertility, and other complications.
Hyperthyroidism: An overactive thyroid gland produces excessive levels of T3 and T4 hormones. This can produce symptoms such as:
Hyperthyroidism can lead to complications such as heart problems, brittle bones, eye problems (especially common with Grave’s disease), and thyrotoxic crisis. This last condition results in a sudden increase in the severity of your symptoms and delirium. A thyrotoxic crisis is a medical emergency and requires immediate care.
A comprehensive thyroid panel will evaluate your thyroid function with 3 different tests:
- TSH test: A thyroid-stimulating hormone (TSH) test is a lab test that evaluates how well your thyroid is working by measuring your thyroid-stimulating hormone. Your doctor may recommend a TSH test if you're experiencing symptoms of hyperthyroidism or hypothyroidism, including anxiety, weight gain/loss, tiredness, hair loss, irregular menstrual periods, changes in your heart rate, puffiness, and more.
- T4 Test: A thyroxine (T4) test measures the level of T4 in the blood.
- T3 Test: A triiodothyronine (T3) test measures the level of T3 in the blood.
Other blood tests that may be performed during a thyroid panel include:
- Thyroid antibody test: This test measures levels of thyroid antibodies that are produced to determine whether or not the immune system is mistakenly creating antibodies to attack the thyroid gland. By doing this, thyroid antibody tests can help detect underlying autoimmune causes of hyper/hypothyroidism such as Grave’s disease or Hashimoto’s disease.
- Thyroglobulin: This test measures the thyroglobulin protein, which is produced by the thyroid gland or thyroid cancer cells. A thyroglobulin test can help detect inflammation of the thyroid gland- especially in patients who have had their thyroid gland removed due to thyroid cancer.
Hyper/ hypothyroidism treatments are meant to manage hormone levels.
For an underactive thyroid, your doctor may prescribe you a hormone replacement medication that will replace the hormones that your thyroid gland is not producing enough of. The most common medication used for this therapy is levothyroxine, which increases the levels of T4 and T3 in your blood.
For an overactive thyroid, your doctor may prescribe methimazole or propylthiouracil, both of which block your thyroid’s ability to make T4 and T3. You may also be prescribed radioactive iodine, an oral tablet that shrinks your thyroid glands. This leads to a decrease in thyroid hormone production but usually results in permanent damage to the thyroid gland. After taking this medication, you may be prescribed hormone replacement therapy to keep hormone levels balanced.