If you feel that any of our content is inaccurate, out-of-date, or otherwise questionable, please leave a comment or contact us at support selfhacked. Note that each number in parentheses [1, 2, 3, etc. Thyroid disorders affect millions worldwide, but they can sometimes be difficult to diagnose. T3 uptake helps doctors calculate your levels of free thyroid hormone, which provides important information on thyroid function.
Find out how this test works and what can cause abnormal results. The thyroid gland produces two main thyroid hormones , called T3 and T4. These thyroid hormones circulate through the blood and have various important roles in the body, such as controlling heartbeat, body temperature, and metabolism [ 1 ]. Both of these hormones can come in two forms. One is the bound form , where T3 or T4 is attached to a protein. This helps the hormones travel through the blood, but also inactivates them.
The other is the free form , which is not attached to a protein but does have biological activity [ 1 ]. This is where T3 uptake testing comes in. This test provides a way to indirectly measure free T4 levels [ 1 , 2 ]. For a more in-depth breakdown of thyroid hormones, check out our article here. The T3 uptake test, also called the T3 resin uptake test, indirectly measures the binding capacity of TBG.
It does not measure T3, despite the name [ 2 ]. TBG, short for thyroxine-binding globulin, is a protein that can bind to T4 and T3. This test can be helpful when abnormalities in thyroid-binding proteins make total T4 levels misleading [ 2 ]. The T3 uptake test must be performed alongside a total T4 test in order to calculate free T4, also called the free T4 index.
A high free T4 index may indicate hyperthyroidism while low levels may point to hypothyroidism [ 2 ]. The T3 uptake test requires a blood sample, which a medical professional will usually take from the vein.
Modern tests can directly measure free T4, making this test obsolete for the most part. Once the blood has been collected, the needle is removed and the area is covered with cotton or a bandage to stop the bleeding. Collecting the blood for the test will only take a few minutes.
Either method heel or vein withdrawal of collecting a blood sample is only temporarily uncomfortable and can feel like a quick pinprick. Afterward, there may be some mild bruising, which should go away in a day or so.
The T3RU is considered a safe procedure. However, as with many medical tests, some problems can occur with having blood drawn. These include:.
Having a blood test is relatively painless. Still, many kids are afraid of needles. Explaining the test in terms your child can understand might help ease any fear. Allow your child to ask the technician any questions he or she might have.
Tell your child to try to relax and stay still during the procedure, as tensing muscles and moving can make it harder and more painful to draw blood. If your results show high total T3 levels or high free T3 levels, it may mean you have hyperthyroidism.
Low T3 levels may mean you have hypothyroidism , a condition in which your body doesn't make enough thyroid hormone. T3 test results are often compared with T4 and TSH test results to help diagnose thyroid disease. Learn more about laboratory tests, reference ranges, and understanding results. Thyroid changes can happen during pregnancy. These changes are usually not serious, and most pregnant women don't need T3 testing. But your health care provider may order a T3 test during pregnancy if you have:.
The information on this site should not be used as a substitute for professional medical care or advice. Contact a health care provider if you have questions about your health. Triiodothyronine T3 Tests. What is a triiodothyronine T3 test? The T3 hormone comes in two forms: Bound T3, which attaches to protein Free T3, which does not attach to anything A test that measures both bound and free T3 is called a total T3 test.
Other names: thyroid function test; total triiodothyronine, free triiodothyronine, FT3. What is it used for? Why do I need a T3 test? You may need a T3 test if you have symptoms of hyperthyroidism. These include: Anxiety Weight loss Tremors in the hands Increased heart rate Bulging of the eyes Trouble sleeping Fatigue Low tolerance for heat More frequent bowel movements.
0コメント