What is a Radioiodine Thyroid Uptake Test?
This test is used to measure how much iodine is taken up by the thyroid gland. Hypothyroid patients usually take up too little iodine and hyperthyroid patients take up too much iodine. The test is performed by giving a tracer dose of radioiodine by mouth. The iodine is concentrated in the thyroid gland or excreted in the urine over the next few hours. When the patient returns, the amount of iodine that went to the thyroid can be measured by a detector placed over the neck. This is called the “thyroid uptake”. Of course patients who are taking thyroid medication will not take up iodine in their thyroid gland because their own thyroid gland is turned off and not functioning. At other times the gland will concentrate iodine normally but will be unable to convert iodine into thyroid hormone; therefore, interpretation of the thyroid uptake is done in conjunction with blood tests. A thyroid uptake is done prior to treatment with radioiodine in order to determine how much iodine is needed for
