What do low t4 levels mean

Bound T4 attaches to proteins that prevent it from entering these tissues. Because T4 is converted into another thyroid hormone called T3 triiodothyronine , free T4 is the more important hormone to measure. Any changes show up in T4 first. 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. You may need this test if your healthcare provider wants to find out whether you have a thyroid-related condition, such as hyperthyroidism, which means an overactive thyroid, or hypothyroidism, which means an underactive thyroid. If you do have a thyroid problem, you may have the test to monitor changes or treatment. Each condition has many different symptoms.

If you have hyperthyroidism, you may often feel anxious and irritable, have trouble sleeping, and have an irregular or rapid heart rhythm.

You may also feel quite tired and notice that you're losing weight even though your appetite has increased. You may also have sweating and increased heat sensitivity, changes to bowel habits, and changes to menstrual patterns, such as a lighter flow. If you have hypothyroidism, you may notice weight gain, even if you aren't overeating. You may also be more sensitive to cold, have low energy, and notice changes to menstruation, such as heavier flow. You may also have muscle weakness, constipation, and dry skin and hair.

You may have blood tests to measure T 3 and TSH. These hormones also play key roles in thyroid health. You may also have blood tests to measure the levels of certain antithyroid antibodies in your blood to get a more accurate diagnosis.

And you may have imaging tests of your thyroid gland. An overactive thyroid or an underactive thyroid can both cause hair loss….

A hyperactive thyroid is when the body produces too much of the hormone thyroxine. If people do not control this, thyroid storm can occur. A person's diet can affect the symptoms of hyperthyroidism. This article looks at which foods and nutrients to eat and which to avoid for an…. A thyroid-stimulating hormone TSH test measures how much TSH is in the blood, which can help doctors diagnose thyroid conditions. Here, we describe…. Some supplements that claim to boost thyroid health are now commercially available.

However, they could lead to dangerous complications. Learn more. What to know about T4 levels. Medically reviewed by Dr. Regulation Normal levels Causes of changes Symptoms Testing Treatment Outlook Summary T4, or thyroxine, is a type of thyroid hormone that regulates metabolism.

How the body normalizes T4 levels. Share on Pinterest T4 levels can affect both bone health and muscle function.

Normal T4 levels. Age Lower limit in picomoles pmol Upper limit pmol less than 6 days 11 32 6—13 days Causes of T4 level changes. Scientists identify new cause of vascular injury in type 2 diabetes. Adolescent depression: Could school screening help? Related Coverage. What to know about thyroid function and hair loss. Medically reviewed by Maria S.

Prelipcean, MD. Because X-ray dyes can include iodine, a recent X-ray involving dye may also raise your T4 test results. More commonly, you may feel pain or discomfort during the blood draw.

You may also bleed slightly after the needle is removed. You may develop a small bruise around the puncture site. A T4 test is a blood test that helps your doctor identify problems with your thyroid.

This will ensure the most accurate interpretation of the test results. 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…. Anthropophobia is a fear of people.

Typically, a fear of people is associated with…. Health Conditions Discover Plan Connect. T4 Test. Medically reviewed by Andrew Gonzalez, M.