Radioactive iodine uptake test is a type of nuclear test performed to evaluate thyroid function. The patient ingests radioactive iodine (I-123 or I-131) capsules or liquid. After a time (usually 6 and 24-hours later), a gamma probe is placed over the thyroid gland to measure the amount of radioiodine uptake in the thyroid gland. The values are then compared.
Review Date 1/26/2020
Updated by: Brent Wisse, MD, board certified in Metabolism/Endocrinology, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.