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    Radioactive Iodine Uptake Test

    Radioactive Iodine Uptake Test



    Results

    A radioactive iodine uptake (RAIU) test uses a Reference radioactive tracer Opens New Window and a special probe to measure how much tracer the Reference thyroid gland Opens New Window absorbs from the blood. The radioactive tracer used in this test is iodine. An RAIU test is done to check for thyroid gland problems, such as Reference hyperthyroidism Opens New Window.

    Radioactive thyroid scan and radioactive iodine uptake test (RAIU)
    Normal:

    The amount of radioactive tracer in the thyroid gland is normal. An RAIU test measures the amount of tracer taken up by the thyroid gland at certain times after the tracer is given. The measured amount of radioactive tracer in the thyroid gland at each one of these times is at normal levels.
    Abnormal:

    The test shows either more or less uptake of tracer than normal in the thyroid gland. The uptake may be even or uneven. If hyperthyroidism is present, abnormal test results may mean certain conditions are present.

    • A low uptake of tracer by the thyroid gland may mean that hyperthyroidism is caused by inflammation of the thyroid gland (Reference thyroiditis Opens New Window), taking too much thyroid medicine, or another rare condition.
    • A high uptake of tracer spread evenly in the thyroid gland may mean that hyperthyroidism is caused by conditions such as Reference Graves' disease Opens New Window.
    • An uneven spread of tracer in the thyroid gland (with either low or high areas of uptake) may mean that hyperthyroidism is caused by a multinodular Reference goiter Opens New Window or a noncancerous (benign) tumor called a toxic adenoma.



    By: Reference Healthwise Staff Last Revised: Reference May 31, 2011
    Medical Review: Reference E. Gregory Thompson, MD - Internal Medicine
    Reference Matthew I. Kim, MD - Endocrinology


    This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Reference Terms of Use. Reference How this information was developed to help you make better health decisions.


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