Radioactive iodine uptake (RAIU) is a test that is used to evaluate the function of the thyroid gland. In this test, a small amount of radioactive iodine is administered to a patient, either orally or through injection. The radioactive iodine is taken up by the thyroid gland, which then emits radiation that can be detected by a special scanner.
The RAIU test measures the amount of radioactive iodine that is taken up by the thyroid gland over a specific period of time, usually several hours. The test is used to evaluate the overall function of the thyroid gland and can help to diagnose conditions such as hyperthyroidism (overactive thyroid) and hypothyroidism (underactive thyroid).
In hyperthyroidism, the thyroid gland is overactive and takes up more iodine than normal, resulting in a high RAIU value. In contrast, in hypothyroidism, the thyroid gland is underactive and takes up less iodine than normal, resulting in a low RAIU value.
The RAIU test is generally considered safe when used in appropriate doses and under the guidance of a healthcare professional. However, as with any medical test that involves exposure to radiation, there is a small risk of side effects, including allergic reactions, radiation sickness, or damage to the thyroid gland or other tissues. The risks of the test should be carefully weighed against the potential benefits in each individual case.