The radioactive iodine uptake test determines if there is too much thyroxine (a thyroid hormone) in the body. After a diagnosis of hyperthyroidism is made, health professionals need to know the reason for the excess thyroid hormone in the body in order to prescribe treatment. For this test, you take an oral dose of radioactive iodine. The iodine collects in your thyroid gland. Either two, six, or 24 hours later, you return to the testing center, and an imaging test shows how much iodine is in your thyroid gland. A lot of iodine indicates your body produces too much thyroxine, indicating that the cause is Graves' disease or hyperfunctioning thyroid nodules. Too little iodine indicates thyroiditis.
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Honor Society of Nursing (STTI) answered
A radioactive iodine uptake (RAIU) test uses a radioactive tracer and a special probe to measure how much tracer the thyroid gland absorbs from the blood. The test can show how much tracer is absorbed by the thyroid gland and if it is evenly spread in the gland. This helps your doctor know if the thyroid gland is working properly. The radioactive tracer commonly used in this test is iodine.
A radioactive iodine uptake test is done to find problems with how the thyroid gland works, such as hyperthyroidism. An RAIU test may be done at the same time as a thyroid scan.
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