This is the most common reason for thyroid hormone tests. Check how well treatment of thyroid disease is working. The total thyroxine T4 , free thyroxine FT4 , and free thyroxine index FTI values are often used to keep track of treatment for hyperthyroidism. Screen newborns to find out if the thyroid gland function is normal. A condition called congenital hypothyroidism can prevent normal growth and development and cause other severe problems, such as intellectual disability, if it is not treated soon after birth.
How To Prepare If you are taking thyroid medicines, tell your doctor when you took your last dose. How It Is Done Blood test A health professional uses a needle to take a blood sample, usually from the arm. Heel stick A heel stick is used to get a blood sample from a baby. How It Feels Blood test When a blood sample is taken, you may feel nothing at all from the needle. Heel stick A brief pain, like a sting or a pinch, is usually felt when the lancet punctures the skin. Risks Blood test There is very little chance of having a problem from this test.
Heel stick There is very little risk of a problem from a heel stick. Results Normal Each lab has a different range for what's normal. Results are usually available within a few days. High values High thyroid hormone levels hyperthyroidism may be caused by: Diseases of the thyroid gland, such as Graves' disease , thyroiditis , or a goiter that contains one or more abnormal growths nodules.
Taking too much thyroid medicine. Low values Low thyroid hormone levels hypothyroidism may be caused by: Thyroid disease, such as thyroiditis. Pituitary gland disease. Destruction of the thyroid gland by surgery or radiation.
T3 and T4 help to control how your body stores and uses energy metabolism. The thyroid hormones also help control many of your body's other processes. These include:. This test can show your healthcare provider if your thyroid gland is overactive hyperthyroidism or underactive hypothyroidism. Eye irritation or bulging eyes; these are symptoms of Graves' disease, a common cause of hyperthyroidism.
You may need other tests to measure thyroid-related substances. TSH receptor-stimulator antibodies, which are used to diagnose Graves disease. Thyroid antiperoxidase antibodies and thyroglobulin antibodies, which are used to diagnose Hashimoto's thyroiditis.
Test results may vary depending on your age, gender, health history, the method used for the test, and other things. Your test results may not mean you have a problem. Ask your healthcare provider what your test results mean for you. The normal range for total T4—both free and bound—varies by laboratory, but the usual range is 4.
For example, if the thyroid stops secreting hormones, the hormones stored in the serum will help delay the onset of hypothyroidism. Conversely, the binding proteins also protect tissues from sudden increases in thyroid secretion or extrathyroidal T3 production. Thyroid function is assessed by one or more of the following tests 1 :. Many laboratories are using strategies such as the following to limit unnecessary laboratory testing 1 :.
This screening method may be used for patients who are at risk of thyroid disease but have not been diagnosed with a thyroid disorder. For patients with a normal TSH level who exhibit signs and symptoms of hyper- or hypothyroidism, or if a pituitary or hypothalamic disease is suspected, a free T4 level should be drawn.
All rights reserved. NursingCenter Blog. Continuing Education More. Mar 15 by Myrna B. Share this on. Thyroid function is assessed by one or more of the following tests 1 : Serum TSH concentration : As stated earlier, there is a relationship between serum free T4 and TSH concentrations in that very small changes in serum free T4 stimulate very large changes in TSH.
Learn why a thyroid-stimulating hormone test is performed, what to expect during the test, and what the test results may mean. A T3 test is a blood test that helps your doctor determine if you have a thyroid problem. Here are some facts you should know about hypothyroidism and how it differs from hyperthyroidism. If you have symptoms of, or a history with thyroid disorders, it may make sense for you to check your TSH levels with an at-home TSH test. These are….
Health Conditions Discover Plan Connect. T4 Test. Medically reviewed by Andrew Gonzalez, M. Why do doctors perform a T4 test? How do you prepare for a T4 test? What do abnormal T4 test results mean? Are there any risks associated with a T4 test? Read this next. Medically reviewed by Kelly Wood, MD. What Is a T3 Test?
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