Radioactive iodine uptake (RAIU) is a test that measures how much radioactive iodine is taken up by the thyroid gland. The test is performed by administering a small amount of radioactive iodine orally, and then measuring the amount of radiation absorbed by the thyroid gland using a radiation detector.
RAIU is used to assess thyroid function, and can help diagnose conditions such as hyperthyroidism (overactive thyroid) or hypothyroidism (underactive thyroid). In hyperthyroidism, the thyroid gland takes up more iodine than usual, leading to increased levels of thyroid hormone production. In hypothyroidism, the thyroid gland takes up less iodine than usual, leading to decreased levels of thyroid hormone production.
RAIU can also be used to help diagnose certain types of thyroid nodules or tumors. Benign nodules tend to take up less iodine than malignant nodules, and a low RAIU value may indicate the presence of a malignant nodule.
RAIU is a safe and non-invasive test, and the amount of radiation used is generally considered to be very low and not harmful to the patient. However, the test is not recommended for pregnant women, as exposure to radiation can harm the developing fetus.
